Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On 05/04/12 14:34, Dennis Gilmore wrote: Fedora at least plans to not support installing hfp and sfp on the same system, while not completely decided I don't think we will be supporting running 32 bit arm binaries on 64 bit arm. there is not a legacy support use case that I can think of i.e. existing common proprietary software. Though I imagine that we will use /lib64 for consistency with existing 64 bit arches. Regardless of what Fedora wants to support in its own environments, it's important that what they do doesn't prevent other distros from supporting multiple flavours if they so wish. That means that there must be at least common agreement on the fundamental naming of the dynamic loader (assuming that the libraries themselves can be found via some config magic). R.
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On 04/10/2012 09:37 AM, Steve McIntyre wrote: Aargh. Again, use of a standard triplet for arm hard-float was agreed by all parties at the Plumbers' meeting last September. For exactly this reason. Now it seems that a number of people have totally ignored that consensus for the last six months. More correctly, I don't think the ARM community disseminated the substance of that agreement to the GCC and other communities. I think standardizing the triplet is a no-brainer and independent of whether or not the triplet shows up in the path/name of the dynamic linker. Furthermore, the ARM GCC maintainers have the ability to standardize the triplet without a long debate on the subject. Jeff
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Tue, Apr 10, 2012 at 8:15 PM, Mike Frysinger vap...@gentoo.org wrote: On Tuesday 10 April 2012 12:46:49 Michael Edwards wrote: That way I can grandfather in binaries with ABI-ignorant hard-coded library paths, and still handle ISA variants. The extranoise might be neon, or ssse3 aren't ISA variants handled already by glibc ? that's what the hwcaps stuff does -- you can put optimized versions in ISA-specific subdirs of the normal lib paths. glibc will look for those first before falling back to the common libs. -mike I stand corrected with regard to non-ABI-altering ISA variations -- except for the nightmare that is Bionic libc, which is out of scope for the present discussion. Googling reminds me that Ulrich covered all this ground in his original document for Linaro (which appears to have moved onto the Debian wiki as http://wiki.debian.org/Multiarch/LibraryPathOverview). So this really is about nothing but freezing the full ABI name (vs. a two-character suffix) into the path to ld.so. And, of course, the implied commitment to resolve any residual ambiguities in the ABI (__cxa_pure_virtual(), anyone?) and to prioritize spec conformance over bug-for-bug compatibility (https://bugs.launchpad.net/gcc-linaro/+bug/952565). When you give something a detailed name, people are more likely to assume that it has a detailed spec, interchangeable among distros and over time. For better or for worse, perpetuating the /lib?? kludge doesn't give that impression. Cheers, - Michael
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On 04/09/2012 11:17 PM, Adam Conrad wrote: Like I said, then, you didn't actually read or understand why proposing multilib paths doesn't work. You realize conceptually, I hope, that there's no guarantee of uniqueness in lib/lib64/lib32/libsf/libhf once you cross the base CPU architecture boundary, right? But what you haven't done is make a case for why anyone should care about this problem. Sure, I said that /libhf/ld-linux.so.3 would *accidentally* work for us right now, due to sheer luck, and you're running with that as saying that we clearly have no problem here worth solving. When the next architecture clashes with linkers on another (hint: it almost certainly will), do we get to argue about this all over again in six months, instead of codifying a new and saner practice now? My understanding of that architecture is that it's being handled as completely different from it's prior implementations. ie, the toolchain and other things are treating it as an entirely separate architecture even though there is some common lineage to prior implementations. If the tools are treating this upcoming architecture as a separate and distinct architecture rather than as a variant of a prior architecture, then why do we have to worry about conflicting in the filesystem space? And just to be clear, I'm not taking sides, merely pointing out that you haven't made the case in this forum in a way that folks understand why this is an important problem. Jeff
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Tue, 10 Apr 2012 07:36:07 +0200 Jakub Jelinek ja...@redhat.com wrote: We really want consistency about the dynamic linker names etc. across different targets and sneaking silently multiarch paths on one architecture would make it inconsistent with all the others. So, please just use /libhf/ld-linux.so.3. I personally find /libhf extremely ugly. If having a second path is a problem, how about using the triplet in the filename? Like: /lib/ld-linux-arm-linux-gnueabihf.so.3 ? Unique per arch and not multiarched. And AFAIK, Linux can handle long filenames just fine... Konstantinos
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Tue, 10 Apr 2012 12:18:51 +0300 Konstantinos Margaritis konstantinos.margari...@linaro.org wrote: On Tue, 10 Apr 2012 07:36:07 +0200 Jakub Jelinek ja...@redhat.com wrote: We really want consistency about the dynamic linker names etc. across different targets and sneaking silently multiarch paths on one architecture would make it inconsistent with all the others. So, please just use /libhf/ld-linux.so.3. I personally find /libhf extremely ugly. If having a second path is a problem, how about using the triplet in the filename? Like: /lib/ld-linux-arm-linux-gnueabihf.so.3 ? Unique per arch and not multiarched. And AFAIK, Linux can handle long filenames just fine... every distro uses a unique triplet, by putting the triplet in there you then need to get all distros to change to using the same triplets. I personally prefer /libhfp rather than /libhf but I am ok with using either. Any change from /lib would need us to do a mass rebuild. because while not 100% needed I would rather keep libraries with the linker. the changes to rpm to support it would be somewhat minimal. we have stated in Fedora though that we have no intention to support mixing hfp and sfp on the same system. we really do need to ensure consensus for arm64 which I think should be /lib64 for 64 bit arch consistency. Dennis
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Tue, 10 Apr 2012 09:32:22 -0500 Dennis Gilmore den...@gilmore.net.au wrote: every distro uses a unique triplet, by putting the triplet in there you then need to get all distros to change to using the same triplets. I personally prefer /libhfp rather than /libhf but I am ok with using either. Any change from /lib would need us to do a mass rebuild. because while not 100% needed I would rather keep libraries with the linker. the changes to rpm to support it would be somewhat minimal. we have stated in Fedora though that we have no intention to support mixing hfp and sfp on the same system. we really do need to ensure consensus for arm64 which I think should be /lib64 for 64 bit arch consistency. Ok, I respect that, what about using the actual ABI name, ie aapcs-vfp? or something that includes both the architecture and the eabi, (arm-hardfloat, armhf, armhfp, etc), but *in* the filename (excluding the case of using a separate directory as it's not too popular). Also, I'm not suggesting changing the triplet or anything, just deciding on a unique name for the triplet. Debian's argument is that the default multilib solution is not future-proof and we would prefer something that is more unique. Regarding /lib64 for aarch64, that's an entirely different discussion, though I do agree it should be also be resolved sooner rather than later as well. Regards Konstantinos
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Tue, Apr 10, 2012 at 09:32:22AM -0500, Dennis Gilmore wrote: On Tue, 10 Apr 2012 12:18:51 +0300 Konstantinos Margaritis konstantinos.margari...@linaro.org wrote: On Tue, 10 Apr 2012 07:36:07 +0200 Jakub Jelinek ja...@redhat.com wrote: We really want consistency about the dynamic linker names etc. across different targets and sneaking silently multiarch paths on one architecture would make it inconsistent with all the others. So, please just use /libhf/ld-linux.so.3. I personally find /libhf extremely ugly. If having a second path is a problem, how about using the triplet in the filename? Like: /lib/ld-linux-arm-linux-gnueabihf.so.3 ? Unique per arch and not multiarched. And AFAIK, Linux can handle long filenames just fine... every distro uses a unique triplet, by putting the triplet in there you then need to get all distros to change to using the same triplets. Aargh. Again, use of a standard triplet for arm hard-float was agreed by all parties at the Plumbers' meeting last September. For exactly this reason. Now it seems that a number of people have totally ignored that consensus for the last six months. I personally prefer /libhfp rather than /libhf but I am ok with using either. Any change from /lib would need us to do a mass rebuild. because while not 100% needed I would rather keep libraries with the linker. the changes to rpm to support it would be somewhat minimal. we have stated in Fedora though that we have no intention to support mixing hfp and sfp on the same system. we really do need to ensure consensus for arm64 which I think should be /lib64 for 64 bit arch consistency. Precisely who in Redhat/Fedora land has the power to make decisions in this area? We've been clearly wasting our time thus far trying to negotiate agreements about the hard-float platform. Cheers, -- Steve McIntyresteve.mcint...@linaro.org http://www.linaro.org/ Linaro.org | Open source software for ARM SoCs
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
FWIW, my use case for multiarch is not sharing the root filesystem among multiple systems. It's sharing the non-lib namespace (/etc, /bin, data) among multiple instruction sets / ABI variants on the same system. I don't need (/usr)?/s?bin to be decorated with a triplet, because the kernel picks a fresh ld.so variant at the execve() boundary; I am happy to mix ARM and x86 binaries (and Python and shell scripts) in /bin, and let the kernel (and binfmt_misc + qemu) sort it out. I only need (/usr)?/lib to be disambiguated *at runtime* because ld.so is not as smart as the kernel. (It's not just ld.so, of course; module/plugin loaders for everything from Python to Firefox have the same problem, and if they don't have the triplet in there somewhere then multiarch breaks them.) As long as the kernel can find the right ld.so and each ld.so can find its own ld.so.conf, I don't really care where the libraries are put at runtime, as long as I can make it different for each ISA/ABI. However, I do care how much autoconf / pkg-config / debhelper misery I have to go through each time I need to pull in another library dependency. Upstream build machinery can usually accommodate /just/about/anything/lib. Trailing components like lib32, libhf, or lib-gnu-autoconf-triplet are not as consistently trivial. Personally, I would like for all shared objects to live in (/usr)?/gnu-autoconf-triplet(-extranoise)?/lib, and for the kernel to take responsibility for pointing (/usr)?/lib at an overlay mount containing whatever makes sense for the currently running binary, a la /proc/self. That way I can grandfather in binaries with ABI-ignorant hard-coded library paths, and still handle ISA variants. The extranoise might be neon, or ssse3, or android (so that non-Android binaries on the same system don't see Android-specific libraries with stupidly generic names like libui.so). And the overlay mount is so that I can, if I choose, build the vast majority of my system without NEON instructions (and thus not take the overhead of VFP context save/restore during timeslices that don't use actual floating point) and still use a subset of those libraries from NEON-anointed binaries (assuming I define some sensible way for the kernel to make that distinction). That isn't necessarily the right solution, of course -- either at a technical level or in the light of the LSB process and other inter-distro politics. But maybe it's at least a more plausible use case for 2012 than NFS-mounting /usr/local on a mix of sun4c, sun4u, and IRIX workstations. (That never did work quite right ...) Cheers, - Michael
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Tue, Apr 3, 2012 at 6:56 PM, Joseph S. Myers jos...@codesourcery.com wrote: (e) Existing practice for cases that do use different dynamic linkers is to use a separate library directory, not just dynamic linker name, as in lib32 and lib64 for MIPS or libx32 for x32; it's certainly a lot easier to make two sets of libraries work in parallel if you have separate library directories like that. So it would seem more appropriate to define a directory libhf for ARM (meaning you need a binutils patch as well to handle that directory, I think), and these different Debian-style names could be implemented separately in a multiarch patch if someone submits one that properly accounts for my review comments on previous patch versions (failure to produce such a fixed patch being why Debian multiarch directory support has not got into GCC so far). The thread doesn't seem to be wrapping up, instead it appears to go in circles :-) As a glibc maintainer, when it comes to this issue, I am guided by: (1) This is a distribution problem and the solution needs to come from a consensus among the distributions. (2) The gcc/glibc community should listen to the distributions. The distributions have the most experience when it comes to whole-system issues. I certainly don't have that experience. Unfortunately *I* give the distributions a B- or C+ for communication. Please make it easy for me to give you an A. It is exceedingly difficult for me to review solutions that span multiple patches, emails, mailing lists, and communities. The best way to avoid rehashing old problems is to document the design and get sign off from the interested parties. If I see uncoordinated and conflicting responses from the distributions... I get worried. Is there a proposal on a wiki that begins to summarize the suggestions and solution? Cheers, Carlos.
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Tuesday 10 April 2012 01:17:36 Adam Conrad wrote: On Tue, Apr 10, 2012 at 12:01:57AM -0400, Mike Frysinger wrote: On Monday 09 April 2012 19:31:40 Adam Conrad wrote: I realize that most people can't see past their own use case to understand why a unique location for linkers is helpful, useful, and important for some other people's use cases, but you either didn't read or chose to ignore why using multilib paths just plain doesn't scale past a single base architecture, and why that's a problem for people who aren't you. and as already stated, the proposed paths here, free of multiarch subpaths, satisfy the requirements that you've put forth Like I said, then, you didn't actually read or understand why proposing multilib paths doesn't work. You realize conceptually, I hope, that there's no guarantee of uniqueness in lib/lib64/lib32/libsf/libhf once you cross the base CPU architecture boundary, right? i don't see this as a problem Sure, I said that /libhf/ld-linux.so.3 would *accidentally* work for us right now, due to sheer luck, and you're running with that as saying that we clearly have no problem here worth solving. my point was: it works today and has no clashes. that satisfies the omg we have to ship something $now and satisfies the requirement that only the Debian people are putting forth (and has already been violated by many targets): the ldso must be unique across all arches/multilibs. When the next architecture clashes with linkers on another (hint: it almost certainly will), do we get to argue about this all over again in six months, instead of codifying a new and saner practice now? i don't buy that it'll happen that soon (since ldso's don't get generated quickly), but that is certainly plenty of time for the Debian project to attempt to convince everyone else that multiarch isn't a waste of time. and does so without holding up moving forward with a unified arm hardfloat abi. -mike signature.asc Description: This is a digitally signed message part.
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Tuesday 10 April 2012 12:46:49 Michael Edwards wrote: That way I can grandfather in binaries with ABI-ignorant hard-coded library paths, and still handle ISA variants. The extranoise might be neon, or ssse3 aren't ISA variants handled already by glibc ? that's what the hwcaps stuff does -- you can put optimized versions in ISA-specific subdirs of the normal lib paths. glibc will look for those first before falling back to the common libs. -mike signature.asc Description: This is a digitally signed message part.
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Thu, Apr 05, 2012 at 10:50:50AM +1200, Michael Hope wrote: On 4 April 2012 18:54, Jakub Jelinek ja...@redhat.com wrote: If the agreement is that arm 32-bit softfp really needs to be installable alongside 32-bit hardfp (and alongside aarch64), then IMHO it should do it like all other multilib ports (x86_64/i?86/x32, s390/s390x, ppc/ppc64, the various MIPS variants) and what FSB says, e.g. use /lib/ld-linux.so.3 and */lib dirs for softfp, /libhf/ld-linux.so.3 and */libhf dirs for hardfp and /lib64/ld-linux.so.3 and */lib64 dirs for aarch64, have 32-bit arm-linux-gnueabi gcc configured for softfp/hardfp multilib with MULTILIB_OSDIRNAMES, etc., have it configured in glibc OK. This gives a different path for the hard float loader and lets the Debian guys add on top of that. I'll ping them and see what they think. The problem here that everyone !Debian isn't taking into account is that multilib paths don't solve our use-case. Multilib paths only solve the case of multiple ABIs on the same base processor family. As soon as you combine x86, arm, power, etc, you end up with overlaps (or, the potential for overlaps; the fact that various arches accidentally have different majors keeps those overlaps to a minimum right now, but that's not by design). Honestly, this is something we should have solved two decades ago, but the very idea that someone would want to do what Debian is now doing didn't occur to any of us. That's cool. We didn't think of it back then. That's no excuse to continue with the status quo just because it's the status quo. To be perfectly clear here, we don't care where the linker goes (really, we don't), we just want it to be both arch and ABI unique. If that means taking a crc32 of a rot-13 of the compiler flags used to define the ABI, and then stuffing the linker in /lib/gobbledygook/ld-linux.so, so be it. If this means setting up a (very) lightweight process with the LSB, where everytime a new distro proposes a shiny new arch/ABI, they submit it, and the LSB assigns them an ABI serial, and we all then agree to toss the linker in /lib/abi-2345/ld-linux, that works too. Don't care. Really don't care. This isn't about trying to force people to switch from multilib to multi- arch, where the former is clearly working fine for them. It's not. This is purely about people bikeshedding about paths they consider un-pretty, while (I hope not maliciously or knowingly?) causing potential overlap and breakage for those of us for whom this actually matters and isn't purely a color selection exercise. In the short term, due to sheer luck, /libhf/ld-linux.so.3 would work for us, purely because that doesn't overlap with any other linkers that Debian currently ships. The fact that the multilib path happens to work doesn't make it correct for our use-case, and certainly doesn't make it correct ongoing. Ultimately, however, I want this solved. We thought we had this solved at Plumbers last fall. To hear now that we didn't involve everyone is disheartening, given that we (we being Debian and Ubuntu) were well outnumbered in that room by people from RedHat, Fedora, ChromeOS, and Gentoo. We all agreed on something back then, and now that I'm three weeks away from shipping an armhf distro, it's all exploded yet again into Bikeshed Part III: The Revenge of Purple Paint. I really want to ship a compiler than stuffs the correct and agreed upon linker in headers. I don't want to see third parties build binaries on Ubuntu that don't run on Fedora. No one wants to see that, I think. Obviously, conversely (though this is much less hassle), I need to be able to ship a linker symlink that matches expectations, so that binaries built on Fedora will run on Ubuntu. Again, I'm sure we all want that. So, pretty please, can we (A) address the concerns here without people putting up the Unique paths are Debian trying to force multi-arch on us straw man, and (B) agree to *something*, before I ship something that conforms to a standard agreed upon more than half a year ago that is now a cause for contention? Pretty please? With sugar on top? Kthx. (of course, aarch64 is going to be new, talking now about the 32-bit softfp vs. hardfp). Yip. I assume something like /lib64 to stay consistent with other architectures. aarch64 is hard float only. I expect that most distros will probably ship their aarch64 libraries in /lib64 (Debian and Ubuntu won't, but that's fine) to keep consistent with their other 64-bit ports, but where you put libraries is entirely unrelated to where the linker lives. You could have all your libraries in /root/.trash/ and if the linker lives in a canonical location and can resolve that, that's fine. I will still (obviously, I think, from my comments above) argue that the linker should live in a guaranteed unique location. Overlap with other arches in /lib64 is certainly far more likely than overlap in /libhf. ... Adam Conrad
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Monday 09 April 2012 16:48:06 Adam Conrad wrote: On Thu, Apr 05, 2012 at 10:50:50AM +1200, Michael Hope wrote: On 4 April 2012 18:54, Jakub Jelinek wrote: If the agreement is that arm 32-bit softfp really needs to be installable alongside 32-bit hardfp (and alongside aarch64), then IMHO it should do it like all other multilib ports (x86_64/i?86/x32, s390/s390x, ppc/ppc64, the various MIPS variants) and what FSB says, e.g. use /lib/ld-linux.so.3 and */lib dirs for softfp, /libhf/ld-linux.so.3 and */libhf dirs for hardfp and /lib64/ld-linux.so.3 and */lib64 dirs for aarch64, have 32-bit arm-linux-gnueabi gcc configured for softfp/hardfp multilib with MULTILIB_OSDIRNAMES, etc., have it configured in glibc OK. This gives a different path for the hard float loader and lets the Debian guys add on top of that. I'll ping them and see what they think. The problem here that everyone !Debian isn't taking into account is that multilib paths don't solve our use-case. Multilib paths only solve the case of multiple ABIs on the same base processor family. As soon as you combine x86, arm, power, etc, you end up with overlaps and the problem there is that you're assuming anyone !Debian sees this as a problem. so, once again, do not use the armhf standardization work to backdoor multiarch. if you want to talk about multiarch, then start a new thread to do that. Ultimately, however, I want this solved. We thought we had this solved at Plumbers last fall. To hear now that we didn't involve everyone is disheartening, given that we (we being Debian and Ubuntu) were well outnumbered in that room by people from RedHat, Fedora, ChromeOS, and Gentoo. tbh, i thought the ldso discussion was more we've been talking about this for a long time, so let's just go with XXX and then people moved on to the next topic (which was defining exactly what hard float abi meant wrt compiler flags). further, it seemed like we had distro representation there, but not mainline gcc people. So, pretty please, can we (A) address the concerns here without people putting up the Unique paths are Debian trying to force multi-arch on us straw man, and (B) agree to *something*, before I ship something that conforms to a standard agreed upon more than half a year ago that is now a cause for contention? Pretty please? With sugar on top? Kthx. again, saying /lib/tuple/ldso isn't multiarch is bunk. but it sounds like you're fine with /libhf/, so there isn't anything left to thrash about there. -mike signature.asc Description: This is a digitally signed message part.
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Mon, Apr 09, 2012 at 07:14:45PM -0400, Mike Frysinger wrote: again, saying /lib/tuple/ldso isn't multiarch is bunk. but it sounds like you're fine with /libhf/, so there isn't anything left to thrash about there. I appreciate your careful reading of my email and the issues I outlined, and I look forward to your new urbandictionary definition of the common colloquialism fine with. A path for one file isn't multi-arch. A unique path for linkers does help facilitate multi-arch, but we're not forcing you to put libraries some place you don't want to, implement new ideas you don't want to, or any other such bunk, as you so obviously impartially put it. I realize that most people can't see past their own use case to understand why a unique location for linkers is helpful, useful, and important for some other people's use cases, but you either didn't read or chose to ignore why using multilib paths just plain doesn't scale past a single base architecture, and why that's a problem for people who aren't you. This isn't about pushing multi-arch on others. This isn't about pushing multi-arch on others. Also, this. Isn't. About. Pushing. Multi-arch. On. Others. I don't know how much more clear I can make that. If the QT guys filed a bug/feature request on libstdc++ asking to change something that didn't break C++ standards, but facilitated some fancy thing they were working on, my response wouldn't be dude, I use GTK, what do I care about your weird needs, screw you and your QT agenda, it would be to ask them why they need the thing they need, evaluate how, if in any way, that would impact other users, and work with them. Using unique linker paths (for new architectures) hurts exactly zero users, and this discussion has taken up FAR MORE developer time than implementation ever would have. Arguing against unique linker paths for the reason that we've never done that before is not helpful, and it's blatantly ignoring technical arguments and hiding them behind some bizarre inter-distro conspiracy theory. Maybe the conspiracy theory is fun for you. I don't know. It's not for me. We were told by GCC upstream that we needed distro consensus. We got that over half a year ago. Now I'm told by distros that the patch not being upstream is why they are backing out of said consensus. Fun. Adam Conrad
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Monday 09 April 2012 19:31:40 Adam Conrad wrote: I realize that most people can't see past their own use case to understand why a unique location for linkers is helpful, useful, and important for some other people's use cases, but you either didn't read or chose to ignore why using multilib paths just plain doesn't scale past a single base architecture, and why that's a problem for people who aren't you. and as already stated, the proposed paths here, free of multiarch subpaths, satisfy the requirements that you've put forth -mike signature.asc Description: This is a digitally signed message part.
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Thursday 05 April 2012 12:25:09 Konstantinos Margaritis wrote: On Thu, 5 Apr 2012 11:55:14 -0400 Mike Frysinger wrote: note: i don't care about /lib/ld-linux-hf.so.3 or /lib/ld-linux.so.4 or /libhf/ld-linux.so.[34]. /lib/triplet/ldso is really the only one i don't think doesn't belong. and I'm just saying that I dislike /libhf, I also think that just raising the version is a wrong solution. i can see why bumping ver # is undesirable, but i don't think it's that big of a deal. the ldso is a bit of a magic beast, so i don't think applying the same SONAME versioning rules is terribly important. especially since ARM has already moved from ld-linux.so.2 for OABI to ld-linux.so.3 for EABI. you could even argue that enshrining hardfloat is actually an ABI version bump, so ld-linux.so.4 is appropriate. and really, once you bump the SONAME, injecting substrings like hf are no different. don't really know what you're talking about here. other distros have no problem with handling multilib. multilib for softfloat/hardfloat on arm? I don't think so, even for other arches -it was already demonstrated that you cannot e.g. have powerpc e500v2 and e600 installed concurrently, i'm not familiar with ppc's embedded variants, so i can't speak to these examples and anyway that's not the topic of the discussion here. Apart from multiarch there is no other solution to do that *for* arm, at least at the moment, because the two ABIs use exactly the same paths on a non-multiarch system. i'm not sure why you think that. if people actually want to do multilib with these, then there's nothing stopping people from doing that, once the ldso's are in a unique path. And I get back to the proposed solution /libhf -which is the multilib path you're referring to- and I'm saying that the topic here is for the linker path alone. In the hypothetical scenario that everyone agreed on /libhf for the linker path, but not for libraries -which would stay in /lib- , then we'd have a /libhf top directory with just one file, the linker. Or a symlink from /lib to /libhf or /lib/triplet to /libhf in Debian's case, but that defeats the purposes of having a new /libhf directory, doesn't it? what Debian chooses to do with multiarch is up to Debian ... i don't think it should have any bearing here. -mike signature.asc Description: This is a digitally signed message part.
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On 04/09/2012 05:14 PM, Mike Frysinger wrote: tbh, i thought the ldso discussion was more we've been talking about this for a long time, so let's just go with XXX and then people moved on to the next topic (which was defining exactly what hard float abi meant wrt compiler flags). further, it seemed like we had distro representation there, but not mainline gcc people. Actually Mike, there was at least one mainline GCC person there. Me. Of course I was thrown into a discussion I knew nothing about, but the goal of having a standardized path to discover ld.so which worked across distros seems like goodness to me. Honestly, I don't see what all the resistance is about. Jeff
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Tuesday 10 April 2012 00:16:34 Jeff Law wrote: On 04/09/2012 05:14 PM, Mike Frysinger wrote: tbh, i thought the ldso discussion was more we've been talking about this for a long time, so let's just go with XXX and then people moved on to the next topic (which was defining exactly what hard float abi meant wrt compiler flags). further, it seemed like we had distro representation there, but not mainline gcc people. Actually Mike, there was at least one mainline GCC person there. Me. my mistake. i don't think we've met before, and that was a fairly busy time for me, so i probably missed things. we should get a beer ;). Of course I was thrown into a discussion I knew nothing about admittedly, that was the first time i've been in a linaro-related meeting before, and i hadn't been following linaro at all before (as the job i left before wasn't working on arm at all) goal of having a standardized path to discover ld.so which worked across distros seems like goodness to me. Honestly, I don't see what all the resistance is about. i think we have suggestions that would work for everyone ... but maybe this thread has gotten too big so we need to regroup with a summary -mike signature.asc Description: This is a digitally signed message part.
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Tue, Apr 10, 2012 at 12:01:57AM -0400, Mike Frysinger wrote: On Monday 09 April 2012 19:31:40 Adam Conrad wrote: I realize that most people can't see past their own use case to understand why a unique location for linkers is helpful, useful, and important for some other people's use cases, but you either didn't read or chose to ignore why using multilib paths just plain doesn't scale past a single base architecture, and why that's a problem for people who aren't you. and as already stated, the proposed paths here, free of multiarch subpaths, satisfy the requirements that you've put forth Like I said, then, you didn't actually read or understand why proposing multilib paths doesn't work. You realize conceptually, I hope, that there's no guarantee of uniqueness in lib/lib64/lib32/libsf/libhf once you cross the base CPU architecture boundary, right? Sure, I said that /libhf/ld-linux.so.3 would *accidentally* work for us right now, due to sheer luck, and you're running with that as saying that we clearly have no problem here worth solving. When the next architecture clashes with linkers on another (hint: it almost certainly will), do we get to argue about this all over again in six months, instead of codifying a new and saner practice now? ... Adam Conrad
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
Em 9 de abril de 2012 17:48, Adam Conrad adcon...@debian.org escreveu: On Thu, Apr 05, 2012 at 10:50:50AM +1200, Michael Hope wrote: On 4 April 2012 18:54, Jakub Jelinek ja...@redhat.com wrote: If the agreement is that arm 32-bit softfp really needs to be installable alongside 32-bit hardfp (and alongside aarch64), then IMHO it should do it like all other multilib ports (x86_64/i?86/x32, s390/s390x, ppc/ppc64, the various MIPS variants) and what FSB says, e.g. use /lib/ld-linux.so.3 and */lib dirs for softfp, /libhf/ld-linux.so.3 and */libhf dirs for hardfp and /lib64/ld-linux.so.3 and */lib64 dirs for aarch64, have 32-bit arm-linux-gnueabi gcc configured for softfp/hardfp multilib with MULTILIB_OSDIRNAMES, etc., have it configured in glibc OK. This gives a different path for the hard float loader and lets the Debian guys add on top of that. I'll ping them and see what they think. The problem here that everyone !Debian isn't taking into account is that multilib paths don't solve our use-case. Multilib paths only solve the case of multiple ABIs on the same base processor family. As soon as you combine x86, arm, power, etc, you end up with overlaps (or, the potential for overlaps; the fact that various arches accidentally have different majors keeps those overlaps to a minimum right now, but that's not by design). Honestly, this is something we should have solved two decades ago, but the very idea that someone would want to do what Debian is now doing didn't occur to any of us. That's cool. We didn't think of it back then. That's no excuse to continue with the status quo just because it's the status quo. To be perfectly clear here, we don't care where the linker goes (really, we don't), we just want it to be both arch and ABI unique. If that means taking a crc32 of a rot-13 of the compiler flags used to define the ABI, and then stuffing the linker in /lib/gobbledygook/ld-linux.so, so be it. If this means setting up a (very) lightweight process with the LSB, where everytime a new distro proposes a shiny new arch/ABI, they submit it, and the LSB assigns them an ABI serial, and we all then agree to toss the linker in /lib/abi-2345/ld-linux, that works too. Don't care. Really don't care. This isn't about trying to force people to switch from multilib to multi- arch, where the former is clearly working fine for them. It's not. This is purely about people bikeshedding about paths they consider un-pretty, while (I hope not maliciously or knowingly?) causing potential overlap and breakage for those of us for whom this actually matters and isn't purely a color selection exercise. In the short term, due to sheer luck, /libhf/ld-linux.so.3 would work for us, purely because that doesn't overlap with any other linkers that Debian currently ships. The fact that the multilib path happens to work doesn't make it correct for our use-case, and certainly doesn't make it correct ongoing. Ultimately, however, I want this solved. We thought we had this solved at Plumbers last fall. To hear now that we didn't involve everyone is disheartening, given that we (we being Debian and Ubuntu) were well outnumbered in that room by people from RedHat, Fedora, ChromeOS, and Gentoo. We all agreed on something back then, and now that I'm three weeks away from shipping an armhf distro, it's all exploded yet again into Bikeshed Part III: The Revenge of Purple Paint. I really want to ship a compiler than stuffs the correct and agreed upon linker in headers. I don't want to see third parties build binaries on Ubuntu that don't run on Fedora. No one wants to see that, I think. Obviously, conversely (though this is much less hassle), I need to be able to ship a linker symlink that matches expectations, so that binaries built on Fedora will run on Ubuntu. Again, I'm sure we all want that. So, pretty please, can we (A) address the concerns here without people putting up the Unique paths are Debian trying to force multi-arch on us straw man, and (B) agree to *something*, before I ship something that conforms to a standard agreed upon more than half a year ago that is now a cause for contention? Pretty please? With sugar on top? Kthx. (of course, aarch64 is going to be new, talking now about the 32-bit softfp vs. hardfp). Yip. I assume something like /lib64 to stay consistent with other architectures. aarch64 is hard float only. I expect that most distros will probably ship their aarch64 libraries in /lib64 (Debian and Ubuntu won't, but that's fine) to keep consistent with their other 64-bit ports, but where you put libraries is entirely unrelated to where the linker lives. You could have all your libraries in /root/.trash/ and if the linker lives in a canonical location and can resolve that, that's fine. I will still (obviously, I think, from my comments above) argue that the linker should live in a guaranteed unique
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Tue, Apr 10, 2012 at 05:17:36AM +, Adam Conrad wrote: On Tue, Apr 10, 2012 at 12:01:57AM -0400, Mike Frysinger wrote: On Monday 09 April 2012 19:31:40 Adam Conrad wrote: I realize that most people can't see past their own use case to understand why a unique location for linkers is helpful, useful, and important for some other people's use cases, but you either didn't read or chose to ignore why using multilib paths just plain doesn't scale past a single base architecture, and why that's a problem for people who aren't you. and as already stated, the proposed paths here, free of multiarch subpaths, satisfy the requirements that you've put forth Like I said, then, you didn't actually read or understand why proposing multilib paths doesn't work. You realize conceptually, I hope, that there's no guarantee of uniqueness in lib/lib64/lib32/libsf/libhf once you cross the base CPU architecture boundary, right? But you are incorrectly assuming that anyone outside Debian actually sees that as a problem. When we've designed multilib for Linux (following Irix layout, which for some weird reason Debian was the only one which ignored it), it hasn't been a goal and I don't see why it should be a goal now. For crossing base CPU architecture boundaries we have for many years --sysroot, you can't run natively the binaries/libraries anyway, while for ABIs that you can run natively it is very common to run binaries for the different native ABIs concurrently. We really want consistency about the dynamic linker names etc. across different targets and sneaking silently multiarch paths on one architecture would make it inconsistent with all the others. So, please just use /libhf/ld-linux.so.3. will), do we get to argue about this all over again in six months, instead of codifying a new and saner practice now? Not everybody agrees it is a saner practice. Jakub
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Wed, 4 Apr 2012 07:09:46 -0500 Dennis Gilmore den...@gilmore.net.au wrote: Fedora does use /lib64 on x86_64 I would personally prefer /libhfp but wouldn't object to /libhf though today we have f17 about to go beta and all of rawhide built using /lib Hi Dennis, One potential problem that is born from the /libhf suggestion is the danger of having a new top level directory (/libhf) with only one file, the dynamic linker. AFAIU it, no distro is currently willing to move away from its existing scheme (/lib), Debian is most likely not going to, at best there could be a symlink /libhf - /lib/triplet, but that is not solving the problem IMHO. What about other distros, if everyone is going to use a symlink for /libhf, then even suggesting it and relying on new top-level directories to solve the problem is the wrong approach. Loic suggested a -IMHO- better solution: to change the dynamic linker filename, not the dir, i.e. /lib/ld-linux-hf.so.3 (for this particular case). My 2c. -- Konstantinos Margaritis konstantinos.margari...@linaro.org
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
El Wed, 4 Apr 2012 08:54:12 +0200 Jakub Jelinek ja...@redhat.com escribió: On Wed, Apr 04, 2012 at 01:34:30PM +1200, Michael Hope wrote: I did two ports of Mandriva to armv7. One of my choice to use softfp, and another hardfp port to be compatible with other distros. But other than a previous armv5 port, there is not much else of Mandriva arm, so, it would be good to have to be able to run binaries for either without resorting to a chroot, and only testing purposes. Bumping major or calling it ld-linux-foo.so.3 is out of question? I suspect /lib/ld-linux-$foo.so.3 would be fine. There's two questions here though: can the hard float loader have a different path and, if so, what should it be? We're still working on the first part. If the agreement is that arm 32-bit softfp really needs to be installable alongside 32-bit hardfp (and alongside aarch64), then IMHO it should do it like all other multilib ports (x86_64/i?86/x32, s390/s390x, ppc/ppc64, the various MIPS variants) and what FSB says, e.g. use /lib/ld-linux.so.3 and */lib dirs for softfp, /libhf/ld-linux.so.3 and */libhf dirs for hardfp and /lib64/ld-linux.so.3 and */lib64 dirs for aarch64, have 32-bit arm-linux-gnueabi gcc configured for softfp/hardfp multilib with MULTILIB_OSDIRNAMES, etc., have it configured in glibc, and for those that choose the Debian layout instead, if it is added somehow configurable into upstream gcc/glibc of course handle it similarly there. I just wonder why that hasn't been done 10 years ago and only needs doing now (of course, aarch64 is going to be new, talking now about the 32-bit softfp vs. hardfp). Fedora at least plans to not support installing hfp and sfp on the same system, while not completely decided I don't think we will be supporting running 32 bit arm binaries on 64 bit arm. there is not a legacy support use case that I can think of i.e. existing common proprietary software. Though I imagine that we will use /lib64 for consistency with existing 64 bit arches. Dennis
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On 04/05/2012 03:30 PM, Konstantinos Margaritis wrote: On Wed, 4 Apr 2012 07:09:46 -0500 Dennis Gilmoreden...@gilmore.net.au wrote: Fedora does use /lib64 on x86_64 I would personally prefer /libhfp but wouldn't object to /libhf though today we have f17 about to go beta and all of rawhide built using /lib Hi Dennis, One potential problem that is born from the /libhf suggestion is the danger of having a new top level directory (/libhf) with only one file, the dynamic linker. AFAIU it, no distro is currently willing to move away from its existing scheme (/lib), Debian is most likely not going to, at best there could be a symlink /libhf - /lib/triplet, but that is not solving the problem IMHO. What about other distros, if everyone is going to use a symlink for /libhf, then even suggesting it and relying on new top-level directories to solve the problem is the wrong approach. Loic suggested a -IMHO- better solution: to change the dynamic linker filename, not the dir, i.e. /lib/ld-linux-hf.so.3 (for this particular case). Note that Fedora is a moving target and there already was a mentioning¹ of /lib/triplet for libraries earlier this year during a developers conference². I am not sure what the current status of that proposal is, but I think it is entirely possible that Fedora may follow the format Debian is using. Cheers, Niels ¹ see page 5 from this presentation: http://rvokal.fedorapeople.org/devconf2012/harald-A_streamlined_and_fully_compatible_Linux_Files.pdf ² http://fedoraproject.org/wiki/DeveloperConference2012
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Wed, Apr 04, 2012 at 01:11:33AM +0200, Jakub Jelinek wrote: On Wed, Apr 04, 2012 at 09:18:59AM +1200, Michael Hope wrote: The subdirectories could be called fred and jim and it would still work. The only thing required is that this part of the naming scheme be agreed amongst the distros. This looks to me like it's turning into a bike-shed painting excerise between the distros out there. That's really sad. I don't think we ever even had the discussion: Debian invented their Debian-internal scheme for managing multiple ABIs. They have in the past used patched versions of gcc, as in the case of x86_64. (cc'ed cross-distro as the discussion is also going on there[1]. This patch continues that) I like the idea of incompatible binaries having different loaders. The path doesn't matter but the concept does. Like i686/x86_64, it gives distros the option to install different binaries alongside each other for compatibility, performance, or upgrade reasons. The compatibility cost is nice and low and lets Debian do some interesting cross development things. Does the dynamic linker itself contain any routines that depend on the soft/hard ABI? That would quite surprise me, so I don't see the point of having different dynamic linkers for those ABIs. One dynamic linker should handle both just fine. That's been discussed previously, yes. While technically quite feasible in terms of code, there's enough potential for confusion that we though it was just simpler to use two different linker binaries. Cheers, -- Steve McIntyresteve.mcint...@linaro.org http://www.linaro.org/ Linaro.org | Open source software for ARM SoCs
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Wed, Apr 04, 2012 at 01:34:30PM +1200, Michael Hope wrote: 2012/4/4 Paulo César Pereira de Andrade I did two ports of Mandriva to armv7. One of my choice to use softfp, and another hardfp port to be compatible with other distros. But other than a previous armv5 port, there is not much else of Mandriva arm, so, it would be good to have to be able to run binaries for either without resorting to a chroot, and only testing purposes. Bumping major or calling it ld-linux-foo.so.3 is out of question? I suspect /lib/ld-linux-$foo.so.3 would be fine. There's two questions here though: can the hard float loader have a different path and, if so, what should it be? We're still working on the first part. We've previously discussed changing the name or the version number of the linker, but there was a worry that compatibility would be broken. Apparently the Meego folks have released a hard-float system using ld-linux.so.3 and were concerned about this. Cheers, -- Steve McIntyresteve.mcint...@linaro.org http://www.linaro.org/ Linaro.org | Open source software for ARM SoCs
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Thursday 05 April 2012 09:30:23 Konstantinos Margaritis wrote: On Wed, 4 Apr 2012 07:09:46 -0500 Dennis Gilmore wrote: Fedora does use /lib64 on x86_64 I would personally prefer /libhfp but wouldn't object to /libhf though today we have f17 about to go beta and all of rawhide built using /lib One potential problem that is born from the /libhf suggestion is the danger of having a new top level directory (/libhf) with only one file, the dynamic linker. AFAIU it, no distro is currently willing to move away from its existing scheme (/lib) i don't think that's true. on an x86_64 system, the 64bit libs are in /lib64/. some distros tried to (pointlessly imo) resist and force 64bits into /lib/ when the native ABI was x86_64 (Gentoo included), but those are legacy imo, and afaik, they didn't break the ldso paths. so in a setup that only has hardfloat binaries, you'd have all the libs in /libhf/, not just the ldso. Loic suggested a -IMHO- better solution: to change the dynamic linker filename, not the dir, i.e. /lib/ld-linux-hf.so.3 (for this particular case). the implication in supporting both hardfloat and softfloat simultaneously is that you'd could have them both installed. thus putting them both in /lib/ doesn't make much sense if you're still going to need /libhf/ to hold everything else. -mike signature.asc Description: This is a digitally signed message part.
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Thursday 05 April 2012 10:38:07 Steve McIntyre wrote: On Wed, Apr 04, 2012 at 01:34:30PM +1200, Michael Hope wrote: 2012/4/4 Paulo César Pereira de Andrade I did two ports of Mandriva to armv7. One of my choice to use softfp, and another hardfp port to be compatible with other distros. But other than a previous armv5 port, there is not much else of Mandriva arm, so, it would be good to have to be able to run binaries for either without resorting to a chroot, and only testing purposes. Bumping major or calling it ld-linux-foo.so.3 is out of question? I suspect /lib/ld-linux-$foo.so.3 would be fine. There's two questions here though: can the hard float loader have a different path and, if so, what should it be? We're still working on the first part. We've previously discussed changing the name or the version number of the linker, but there was a worry that compatibility would be broken. Apparently the Meego folks have released a hard-float system using ld-linux.so.3 and were concerned about this. i'm not sure how changing the leading dir components but leaving the base path the same would be any more or less work for meego to maintain backwards compatibility. whatever random path is picked, they're going to be broken, as the ELF encodes the full path to the ldso. -mike signature.asc Description: This is a digitally signed message part.
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Thu, 5 Apr 2012 11:08:56 -0400 Mike Frysinger vap...@gentoo.org wrote: i don't think that's true. on an x86_64 system, the 64bit libs are in /lib64/. some distros tried to (pointlessly imo) resist and force 64bits into /lib/ when the native ABI was x86_64 (Gentoo included), but those are legacy imo, and afaik, they didn't break the ldso paths. so in a setup that only has hardfloat binaries, you'd have all the libs in /libhf/, not just the ldso. That's exactly my concern. If /libhf is chosen for the dymamic linker path, but it's not adopted by everyone else for libraries and other files, then at best you'd have a symlink, at worst a dir with only one file inside. the implication in supporting both hardfloat and softfloat simultaneously is that you'd could have them both installed. thus putting them both in /lib/ doesn't make much sense if you're still going to need /libhf/ to hold everything else. That case has only any chance of realization in a multiarch environment such as Debian/Ubuntu. The rest won't be affected at all. And the dynamic linkers -different filename of course- are the only libs that will be in /lib straight, the rest will be in /lib/triplet. So there is no danger of any conflict, at least not with libraries. -- Konstantinos Margaritis konstantinos.margari...@linaro.org
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
Em 5 de abril de 2012 12:09, Mike Frysinger vap...@gentoo.org escreveu: On Thursday 05 April 2012 10:38:07 Steve McIntyre wrote: On Wed, Apr 04, 2012 at 01:34:30PM +1200, Michael Hope wrote: 2012/4/4 Paulo César Pereira de Andrade I did two ports of Mandriva to armv7. One of my choice to use softfp, and another hardfp port to be compatible with other distros. But other than a previous armv5 port, there is not much else of Mandriva arm, so, it would be good to have to be able to run binaries for either without resorting to a chroot, and only testing purposes. Bumping major or calling it ld-linux-foo.so.3 is out of question? I suspect /lib/ld-linux-$foo.so.3 would be fine. There's two questions here though: can the hard float loader have a different path and, if so, what should it be? We're still working on the first part. We've previously discussed changing the name or the version number of the linker, but there was a worry that compatibility would be broken. Apparently the Meego folks have released a hard-float system using ld-linux.so.3 and were concerned about this. i'm not sure how changing the leading dir components but leaving the base path the same would be any more or less work for meego to maintain backwards compatibility. whatever random path is picked, they're going to be broken, as the ELF encodes the full path to the ldso. -mike I guess now it is too late to defer --with-float=hard for 64 bit armv8, but besides possibly tedious, full rebuilds of, (hopefully) yet to be released hardfp distros per se is not a bad thing. My suggestion for lib$color is $color == vfp (one could choose neon :-), and then it is a distro choice if using /lib as software float to be able to install the same binaries on armv4+, or build with vfp but use software float abi so that armv4+ binaries work. Major issue IMO is that things are being done thinking too much on the now, so, hardfp is good to support nvidia drivers, and plain soft float (armv5) is good for raspberry pi... ___ cross-distro mailing list cross-dis...@lists.linaro.org http://lists.linaro.org/mailman/listinfo/cross-distro Paulo
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Thursday 05 April 2012 11:24:15 Konstantinos Margaritis wrote: On Thu, 5 Apr 2012 11:08:56 -0400 Mike Frysinger wrote: i don't think that's true. on an x86_64 system, the 64bit libs are in /lib64/. some distros tried to (pointlessly imo) resist and force 64bits into /lib/ when the native ABI was x86_64 (Gentoo included), but those are legacy imo, and afaik, they didn't break the ldso paths. so in a setup that only has hardfloat binaries, you'd have all the libs in /libhf/, not just the ldso. That's exactly my concern. If /libhf is chosen for the dymamic linker path, but it's not adopted by everyone else for libraries and other files, then at best you'd have a symlink, at worst a dir with only one file inside. if gcc declares libhf as another multilib target, then everyone else will get it automatically note: i don't care about /lib/ld-linux-hf.so.3 or /lib/ld-linux.so.4 or /libhf/ld-linux.so.[34]. /lib/triplet/ldso is really the only one i don't think doesn't belong. the implication in supporting both hardfloat and softfloat simultaneously is that you'd could have them both installed. thus putting them both in /lib/ doesn't make much sense if you're still going to need /libhf/ to hold everything else. That case has only any chance of realization in a multiarch environment such as Debian/Ubuntu. don't really know what you're talking about here. other distros have no problem with handling multilib. -mike signature.asc Description: This is a digitally signed message part.
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Thu, Apr 05, 2012 at 11:32:39AM +1200, Michael Hope wrote: So: * Big endian: undefined, defaults to /lib/ld-linux.so.3 * Little endian, soft float: /lib/ld-linux.so.3 * Little endian, hard float: /libhf/ld-linux.so.3 Standard upstream practice supports having multiple variants that plausibly run on the same system at the same time, such as /lib and /lib64, and it seems reasonable to support hard and soft float variants that way via a directory such as /libhf. The Debian-style paths are not the default on any other architecture and I don't think it's appropriate to make them the default for this particular case only. OK. Debian multiarch covers libraries and headers but not executables. As a MIPS hard float /usr/bin/ls would collide with an ARM hard float /usr/bin/ls then it's fine for the loader names to potentially collide as well. In practice they wouldn't as most architecture has a subtily different loader name (cf. ld.so.1 for MIPS, ld-linux.so.2 for i386, and ld-linux.so.3 for ARM). Yes, thankfully. More by luck than any design. Cheers, -- Steve McIntyresteve.mcint...@linaro.org http://www.linaro.org/ Linaro.org | Open source software for ARM SoCs
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Thu, Apr 05, 2012 at 01:16:27PM +1200, Michael Hope wrote: On 5 April 2012 12:07, Joseph S. Myers jos...@codesourcery.com wrote: No. A system is either purely hard-float or purely soft-float, and the same paths are used for both so they can't coexist. (Mismatches at *static* link time are detected through object attributes.) Ah, the same as ARM then. The MIPS community would need something similar to this patch if they wanted to support soft and hard float side by side. Yes, definitely. Big endian is extremely uncommon on ARM and I'd rather define it when needed. For strictness sake I'll change the patch to use the new path for hard float little endian only. I don't think that's correct; the new path should be used independent of endian, just as the existing path is. OK. But any multiarch support patch should presumably define separate multiarch paths for each endianness. That's up to Debian. I've asked for documentation on the final tuples and what they mean as the one at: http://wiki.debian.org/Multiarch/Tuples is out of date. I prefer defining what is needed now and doing others as needed. I'm most of the way through an update for that page now; I'll ask for comments/review shortly. Cheers, -- Steve McIntyresteve.mcint...@linaro.org http://www.linaro.org/ Linaro.org | Open source software for ARM SoCs
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Thu, Apr 05, 2012 at 11:08:56AM -0400, Mike Frysinger wrote: On Thursday 05 April 2012 09:30:23 Konstantinos Margaritis wrote: On Wed, 4 Apr 2012 07:09:46 -0500 Dennis Gilmore wrote: Fedora does use /lib64 on x86_64 I would personally prefer /libhfp but wouldn't object to /libhf though today we have f17 about to go beta and all of rawhide built using /lib One potential problem that is born from the /libhf suggestion is the danger of having a new top level directory (/libhf) with only one file, the dynamic linker. AFAIU it, no distro is currently willing to move away from its existing scheme (/lib) i don't think that's true. on an x86_64 system, the 64bit libs are in /lib64/. some distros tried to (pointlessly imo) resist and force 64bits into /lib/ when the native ABI was x86_64 (Gentoo included), but those are legacy imo, and afaik, they didn't break the ldso paths. so in a setup that only has hardfloat binaries, you'd have all the libs in /libhf/, not just the ldso. Loic suggested a -IMHO- better solution: to change the dynamic linker filename, not the dir, i.e. /lib/ld-linux-hf.so.3 (for this particular case). the implication in supporting both hardfloat and softfloat simultaneously is that you'd could have them both installed. thus putting them both in /lib/ doesn't make much sense if you're still going to need /libhf/ to hold everything else. Except you wouldn't - the Debian/Ubuntu plan with multi-arch is to put them all in cleanly-separated paths corresponding to the triplets. I'm concerned that the potential proliferation of /lib* directories here could become very messy over time. I'm surprised that people seem to be happy to invent another namespace on a much more ad-hoc and arbitrary basis than the (mostly) well-understood triplets that we already have defined in the toolchains. Multi-arch is an attempt to make things cleaner for those of us that care about having lots of different platforms supported in parallel. Seen against that background, I was hoping that using the multi-arch path for the armhf linker would make sense. For people that don't care about multi-arch for themselves, a simple symbolic link is all that's needed. Cheers, -- Steve McIntyresteve.mcint...@linaro.org http://www.linaro.org/ Linaro.org | Open source software for ARM SoCs
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Thu, 5 Apr 2012 11:55:14 -0400 Mike Frysinger vap...@gentoo.org wrote: note: i don't care about /lib/ld-linux-hf.so.3 or /lib/ld-linux.so.4 or /libhf/ld-linux.so.[34]. /lib/triplet/ldso is really the only one i don't think doesn't belong. and I'm just saying that I dislike /libhf, I also think that just raising the version is a wrong solution. don't really know what you're talking about here. other distros have no problem with handling multilib. multilib for softfloat/hardfloat on arm? I don't think so, even for other arches -it was already demonstrated that you cannot e.g. have powerpc e500v2 and e600 installed concurrently, and anyway that's not the topic of the discussion here. Apart from multiarch there is no other solution to do that *for* arm, at least at the moment, because the two ABIs use exactly the same paths on a non-multiarch system. And I get back to the proposed solution /libhf -which is the multilib path you're referring to- and I'm saying that the topic here is for the linker path alone. In the hypothetical scenario that everyone agreed on /libhf for the linker path, but not for libraries -which would stay in /lib- , then we'd have a /libhf top directory with just one file, the linker. Or a symlink from /lib to /libhf or /lib/triplet to /libhf in Debian's case, but that defeats the purposes of having a new /libhf directory, doesn't it? I hope I was clearer now. -- Konstantinos Margaritis konstantinos.margari...@linaro.org
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Thursday 05 April 2012 12:15:41 Steve McIntyre wrote: On Thu, Apr 05, 2012 at 11:08:56AM -0400, Mike Frysinger wrote: On Thursday 05 April 2012 09:30:23 Konstantinos Margaritis wrote: Loic suggested a -IMHO- better solution: to change the dynamic linker filename, not the dir, i.e. /lib/ld-linux-hf.so.3 (for this particular case). the implication in supporting both hardfloat and softfloat simultaneously is that you'd could have them both installed. thus putting them both in /lib/ doesn't make much sense if you're still going to need /libhf/ to hold everything else. Except you wouldn't - the Debian/Ubuntu plan with multi-arch is to put them all in cleanly-separated paths corresponding to the triplets. /lib/ and /libhf/ is just as clean as /lib/ and /lib64/ (and now /libx32/). i see no difference here with a gcc configured for these multilib paths. I'm concerned that the potential proliferation of /lib* directories here could become very messy over time. I'm surprised that people seem to be happy to invent another namespace on a much more ad-hoc and arbitrary basis than the (mostly) well-understood triplets that we already have defined in the toolchains. the triplet situation isn't as clean as you imply here. there are already examples of not being able to tell the ABI based purely on that. mips64- linux-gnu could be n32 or n64. x86_64-linux-gnu could be x86_64 or x32. the Debian multiarch project might have made up new triplets to account for this, but those don't translate exactly into the same triplet that are used for e.g. configure --host. Multi-arch is an attempt to make things cleaner for those of us that care about having lots of different platforms supported in parallel. Seen against that background, I was hoping that using the multi-arch path for the armhf linker would make sense. if you think that's a useful goal, then sure. but not everyone thinks the multiarch proposal is really all that useful. however, that (much larger) discussion is really out of scope here. For people that don't care about multi-arch for themselves, a simple symbolic link is all that's needed. i think it's safe to say that the wider community has yet to be convinced, so extending existing support via the existing standards makes more sense. -mike signature.asc Description: This is a digitally signed message part.
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Wed, Apr 04, 2012 at 01:34:30PM +1200, Michael Hope wrote: I did two ports of Mandriva to armv7. One of my choice to use softfp, and another hardfp port to be compatible with other distros. But other than a previous armv5 port, there is not much else of Mandriva arm, so, it would be good to have to be able to run binaries for either without resorting to a chroot, and only testing purposes. Bumping major or calling it ld-linux-foo.so.3 is out of question? I suspect /lib/ld-linux-$foo.so.3 would be fine. There's two questions here though: can the hard float loader have a different path and, if so, what should it be? We're still working on the first part. If the agreement is that arm 32-bit softfp really needs to be installable alongside 32-bit hardfp (and alongside aarch64), then IMHO it should do it like all other multilib ports (x86_64/i?86/x32, s390/s390x, ppc/ppc64, the various MIPS variants) and what FSB says, e.g. use /lib/ld-linux.so.3 and */lib dirs for softfp, /libhf/ld-linux.so.3 and */libhf dirs for hardfp and /lib64/ld-linux.so.3 and */lib64 dirs for aarch64, have 32-bit arm-linux-gnueabi gcc configured for softfp/hardfp multilib with MULTILIB_OSDIRNAMES, etc., have it configured in glibc, and for those that choose the Debian layout instead, if it is added somehow configurable into upstream gcc/glibc of course handle it similarly there. I just wonder why that hasn't been done 10 years ago and only needs doing now (of course, aarch64 is going to be new, talking now about the 32-bit softfp vs. hardfp). One needs to wonder also why arm hasn't switched to 128-bit long double when all other mainstream architectures did (I hope at least aarch64 will use it by default). Jakub
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On 04/03/2012 11:53 AM, Richard Earnshaw wrote: Now, I wonder why the dynamic linker cannot figure out the ABI itself by means of using ELF flags or so? There are no ELF flags for this in executables. The attributes only apply to object files and anyway they are too expensive to decode at run time. Isn't that the core problem, then? We have incompatible libraries and executables but they aren't marked as such. Andrew.
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Wed, 4 Apr 2012, Michael Hope wrote: The tricky one is new GCC with old GLIBC. GCC may have to do a configure time test and fall back to /lib/ld-linux.so.3 if the hard float loader is missing. I don't think that's appropriate for ABI issues. If a different dynamic linker name is specified, GCC should use it unconditionally (and require new enough glibc or a glibc installation that was appropriately rearranged). I have no idea whether shlib-versions files naming a file in a subdirectory will work - but if not, you'd need to send a patch to libc-alpha to support dynamic linkers in subdirectories, with appropriate justification for why you are doing something different from all other architectures. Understood. For now this is just a path. There's more infrastructure work needed if the path includes a directory. Formally it's just a path - but an important feature of GNU/Linux and the GNU toolchain is consistency between different architectures and existing upstream practice is that the dynamic linker is always in the same directory as the other associated libraries and that this has the form /libsomething. In the absence of a compelling reason, which I have not seen stated, to do otherwise for a single case, I think that existing practice should be followed with the dynamic linker being in a directory such as /libhf. The more infrastructure work needed makes clear that you need libc-alpha buy-in *before* putting any patches into GCC or ports. But maybe if you don't try to put the dynamic linker in a different directory from the other libraries, it's easier to support via existing mechanisms (setting slibdir differently if --enable-multiarch-directories or similar)? Do the MIPS or PowerPC loaders detect the ABI and change the library path based on that? I couldn't tell from the code. No, they don't detect the ABI. Both ABIs (and, for Power, the e500v1 and e500v2 variants - compatible with soft-float at the function-calling level but with some glibc ABI differences with soft-float and with each other) use the same directories. (e) Existing practice for cases that do use different dynamic linkers is to use a separate library directory, not just dynamic linker name, as in lib32 and lib64 for MIPS or libx32 for x32; it's certainly a lot easier to make two sets of libraries work in parallel if you have separate library directories like that. Is this required, or should it be left to the distro to choose? Once the loader is in control then it can account for any distro specific features, which may be the standard /lib and /usr/lib for single ABI distros like Fedora or /usr/lib/$tuple for multiarch distros like Ubuntu and Debian. I thought Fedora used the standard upstream /lib64 on x86_64 and so would naturally use a standard upstream /libhf where appropriate. So it would seem more appropriate to define a directory libhf for ARM (meaning you need a binutils patch as well to handle that directory, I think) I'd like to leave that discussion for now. The Debian goal is to support incompatible ABIs and, past that, incompatible architectures. libhf is ambiguous as you could have a MIPS hard float library installed on the same system as an ARM hard float library. If you want both ARM and MIPS hard-float then I'd think you want both big-endian and little-endian ARM hard-float - but your patch defines the same dynamic linker name for both of those. Standard upstream practice supports having multiple variants that plausibly run on the same system at the same time, such as /lib and /lib64, and it seems reasonable to support hard and soft float variants that way via a directory such as /libhf. The Debian-style paths are not the default on any other architecture and I don't think it's appropriate to make them the default for this particular case only. and these different Debian-style names could be implemented separately in a multiarch patch if someone submits one that properly accounts for my review comments on previous patch versions (failure to produce such a fixed patch being why Debian multiarch directory support has not got into GCC so far). Agreed. Note that this loader path discussion is unrelated to multiarch. It came from the same people so there's a family resemblance. I think it's directly related, and that such a path is inappropriate by default; that ARM should be consistent with other architectures, and that if you want to support paths in such subdirectories that would be a separate multiarch patch series for GCC, binutils and glibc (but the PT_INTERP would still use /libwhatever/name without subdirectories in any case). -- Joseph S. Myers jos...@codesourcery.com
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Wed, 4 Apr 2012, Jakub Jelinek wrote: If the agreement is that arm 32-bit softfp really needs to be installable alongside 32-bit hardfp (and alongside aarch64), then IMHO it should do it like all other multilib ports (x86_64/i?86/x32, s390/s390x, ppc/ppc64, the various MIPS variants) and what FSB says, e.g. use /lib/ld-linux.so.3 and */lib dirs for softfp, /libhf/ld-linux.so.3 and */libhf dirs for hardfp and /lib64/ld-linux.so.3 and */lib64 dirs for aarch64, have 32-bit arm-linux-gnueabi gcc configured for softfp/hardfp multilib with MULTILIB_OSDIRNAMES, etc., have it configured in glibc, and for those that choose the Debian layout instead, if it is added somehow configurable into upstream gcc/glibc of course handle it similarly there. I just wonder why that hasn't been done 10 years ago and only needs doing now (of course, aarch64 is going to be new, talking now about the 32-bit softfp vs. hardfp). Exactly. The default should follow the existing practice for other architectures. One needs to wonder also why arm hasn't switched to 128-bit long double when all other mainstream architectures did (I hope at least aarch64 will use it by default). The AArch64 ABI (generic, not GNU/Linux, and draft, still subject to incompatible change) is public and used 128-bit long double the last time I checked. My presumption is that there has been no demand for long double wider than double among 32-bit ARM users. -- Joseph S. Myers jos...@codesourcery.com
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Wed, 4 Apr 2012 09:06:05 + (UTC) Joseph S. Myers jos...@codesourcery.com wrote: On Wed, 4 Apr 2012, Michael Hope wrote: The tricky one is new GCC with old GLIBC. GCC may have to do a configure time test and fall back to /lib/ld-linux.so.3 if the hard float loader is missing. I don't think that's appropriate for ABI issues. If a different dynamic linker name is specified, GCC should use it unconditionally (and require new enough glibc or a glibc installation that was appropriately rearranged). I have no idea whether shlib-versions files naming a file in a subdirectory will work - but if not, you'd need to send a patch to libc-alpha to support dynamic linkers in subdirectories, with appropriate justification for why you are doing something different from all other architectures. Understood. For now this is just a path. There's more infrastructure work needed if the path includes a directory. Formally it's just a path - but an important feature of GNU/Linux and the GNU toolchain is consistency between different architectures and existing upstream practice is that the dynamic linker is always in the same directory as the other associated libraries and that this has the form /libsomething. In the absence of a compelling reason, which I have not seen stated, to do otherwise for a single case, I think that existing practice should be followed with the dynamic linker being in a directory such as /libhf. Consistency across architectures is why Fedora does many of the things the way it does, It really doesn't make much sense to me to diverge from that. The more infrastructure work needed makes clear that you need libc-alpha buy-in *before* putting any patches into GCC or ports. But maybe if you don't try to put the dynamic linker in a different directory from the other libraries, it's easier to support via existing mechanisms (setting slibdir differently if --enable-multiarch-directories or similar)? Do the MIPS or PowerPC loaders detect the ABI and change the library path based on that? I couldn't tell from the code. No, they don't detect the ABI. Both ABIs (and, for Power, the e500v1 and e500v2 variants - compatible with soft-float at the function-calling level but with some glibc ABI differences with soft-float and with each other) use the same directories. (e) Existing practice for cases that do use different dynamic linkers is to use a separate library directory, not just dynamic linker name, as in lib32 and lib64 for MIPS or libx32 for x32; it's certainly a lot easier to make two sets of libraries work in parallel if you have separate library directories like that. Is this required, or should it be left to the distro to choose? Once the loader is in control then it can account for any distro specific features, which may be the standard /lib and /usr/lib for single ABI distros like Fedora or /usr/lib/$tuple for multiarch distros like Ubuntu and Debian. I thought Fedora used the standard upstream /lib64 on x86_64 and so would naturally use a standard upstream /libhf where appropriate. Fedora does use /lib64 on x86_64 I would personally prefer /libhfp but wouldn't object to /libhf though today we have f17 about to go beta and all of rawhide built using /lib Fedora also has software floating point being installed into /lib also So it would seem more appropriate to define a directory libhf for ARM (meaning you need a binutils patch as well to handle that directory, I think) Dennis
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On 4 April 2012 18:54, Jakub Jelinek ja...@redhat.com wrote: On Wed, Apr 04, 2012 at 01:34:30PM +1200, Michael Hope wrote: I did two ports of Mandriva to armv7. One of my choice to use softfp, and another hardfp port to be compatible with other distros. But other than a previous armv5 port, there is not much else of Mandriva arm, so, it would be good to have to be able to run binaries for either without resorting to a chroot, and only testing purposes. Bumping major or calling it ld-linux-foo.so.3 is out of question? I suspect /lib/ld-linux-$foo.so.3 would be fine. There's two questions here though: can the hard float loader have a different path and, if so, what should it be? We're still working on the first part. If the agreement is that arm 32-bit softfp really needs to be installable alongside 32-bit hardfp (and alongside aarch64), then IMHO it should do it like all other multilib ports (x86_64/i?86/x32, s390/s390x, ppc/ppc64, the various MIPS variants) and what FSB says, e.g. use /lib/ld-linux.so.3 and */lib dirs for softfp, /libhf/ld-linux.so.3 and */libhf dirs for hardfp and /lib64/ld-linux.so.3 and */lib64 dirs for aarch64, have 32-bit arm-linux-gnueabi gcc configured for softfp/hardfp multilib with MULTILIB_OSDIRNAMES, etc., have it configured in glibc OK. This gives a different path for the hard float loader and lets the Debian guys add on top of that. I'll ping them and see what they think. and for those that choose the Debian layout instead, if it is added somehow configurable into upstream gcc/glibc of course handle it similarly there. Agreed. I just wonder why that hasn't been done 10 years ago and only needs doing now FPUs have only become common on ARM in the last few years. softfp was a good interim work around but performance is significantly better with hard float. (of course, aarch64 is going to be new, talking now about the 32-bit softfp vs. hardfp). Yip. I assume something like /lib64 to stay consistent with other architectures. aarch64 is hard float only. -- Michael
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On 4 April 2012 21:06, Joseph S. Myers jos...@codesourcery.com wrote: On Wed, 4 Apr 2012, Michael Hope wrote: The tricky one is new GCC with old GLIBC. GCC may have to do a configure time test and fall back to /lib/ld-linux.so.3 if the hard float loader is missing. I don't think that's appropriate for ABI issues. If a different dynamic linker name is specified, GCC should use it unconditionally (and require new enough glibc or a glibc installation that was appropriately rearranged). OK. I want GCC 4.7.1 to use the new path. Does this mean that released versions of GLIBC and GCC 4.7.1 will be incompatible, or does GLIBC pick the path up from GCC? I have no idea whether shlib-versions files naming a file in a subdirectory will work - but if not, you'd need to send a patch to libc-alpha to support dynamic linkers in subdirectories, with appropriate justification for why you are doing something different from all other architectures. Understood. For now this is just a path. There's more infrastructure work needed if the path includes a directory. Formally it's just a path - but an important feature of GNU/Linux and the GNU toolchain is consistency between different architectures and existing upstream practice is that the dynamic linker is always in the same directory as the other associated libraries and that this has the form /libsomething. In the absence of a compelling reason, which I have not seen stated, to do otherwise for a single case, I think that existing practice should be followed with the dynamic linker being in a directory such as /libhf. OK. This matches Jakub's email. The more infrastructure work needed makes clear that you need libc-alpha buy-in *before* putting any patches into GCC or ports. OK. I'm glad we had this discussion as it had to start somewhere. I'll do a follow up across gcc-patches, libc-alpha, and binutils. But maybe if you don't try to put the dynamic linker in a different directory from the other libraries, it's easier to support via existing mechanisms (setting slibdir differently if --enable-multiarch-directories or similar)? OK. /libhf may fit that better. Do the MIPS or PowerPC loaders detect the ABI and change the library path based on that? I couldn't tell from the code. No, they don't detect the ABI. Both ABIs (and, for Power, the e500v1 and e500v2 variants - compatible with soft-float at the function-calling level but with some glibc ABI differences with soft-float and with each other) use the same directories. Sorry, I'm confused. I had a poke about with MIPS and it uses different argument registers for soft and hard float. Soft float uses $4 and hard float $f0. Are there shims or similar installed by the loader? (e) Existing practice for cases that do use different dynamic linkers is to use a separate library directory, not just dynamic linker name, as in lib32 and lib64 for MIPS or libx32 for x32; it's certainly a lot easier to make two sets of libraries work in parallel if you have separate library directories like that. Is this required, or should it be left to the distro to choose? Once the loader is in control then it can account for any distro specific features, which may be the standard /lib and /usr/lib for single ABI distros like Fedora or /usr/lib/$tuple for multiarch distros like Ubuntu and Debian. I thought Fedora used the standard upstream /lib64 on x86_64 and so would naturally use a standard upstream /libhf where appropriate. Good. Dennis said the same. So it would seem more appropriate to define a directory libhf for ARM (meaning you need a binutils patch as well to handle that directory, I think) I'd like to leave that discussion for now. The Debian goal is to support incompatible ABIs and, past that, incompatible architectures. libhf is ambiguous as you could have a MIPS hard float library installed on the same system as an ARM hard float library. If you want both ARM and MIPS hard-float then I'd think you want both big-endian and little-endian ARM hard-float - but your patch defines the same dynamic linker name for both of those. Big endian is extremely uncommon on ARM and I'd rather define it when needed. For strictness sake I'll change the patch to use the new path for hard float little endian only. So: * Big endian: undefined, defaults to /lib/ld-linux.so.3 * Little endian, soft float: /lib/ld-linux.so.3 * Little endian, hard float: /libhf/ld-linux.so.3 Standard upstream practice supports having multiple variants that plausibly run on the same system at the same time, such as /lib and /lib64, and it seems reasonable to support hard and soft float variants that way via a directory such as /libhf. The Debian-style paths are not the default on any other architecture and I don't think it's appropriate to make them the default for this particular case only. OK. Debian multiarch covers libraries and headers but not
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Thu, 5 Apr 2012, Michael Hope wrote: I don't think that's appropriate for ABI issues. If a different dynamic linker name is specified, GCC should use it unconditionally (and require new enough glibc or a glibc installation that was appropriately rearranged). OK. I want GCC 4.7.1 to use the new path. Does this mean that released versions of GLIBC and GCC 4.7.1 will be incompatible, or does GLIBC pick the path up from GCC? Released versions would be incompatible (you could make GCC check at configure time for too-old glibc if --with-float=hard); the path needs hardcoding in both places. Do the MIPS or PowerPC loaders detect the ABI and change the library path based on that? I couldn't tell from the code. No, they don't detect the ABI. Both ABIs (and, for Power, the e500v1 and e500v2 variants - compatible with soft-float at the function-calling level but with some glibc ABI differences with soft-float and with each other) use the same directories. Sorry, I'm confused. I had a poke about with MIPS and it uses different argument registers for soft and hard float. Soft float uses $4 and hard float $f0. Are there shims or similar installed by the loader? No. A system is either purely hard-float or purely soft-float, and the same paths are used for both so they can't coexist. (Mismatches at *static* link time are detected through object attributes.) Big endian is extremely uncommon on ARM and I'd rather define it when needed. For strictness sake I'll change the patch to use the new path for hard float little endian only. I don't think that's correct; the new path should be used independent of endian, just as the existing path is. But any multiarch support patch should presumably define separate multiarch paths for each endianness. -- Joseph S. Myers jos...@codesourcery.com
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On 5 April 2012 12:07, Joseph S. Myers jos...@codesourcery.com wrote: On Thu, 5 Apr 2012, Michael Hope wrote: I don't think that's appropriate for ABI issues. If a different dynamic linker name is specified, GCC should use it unconditionally (and require new enough glibc or a glibc installation that was appropriately rearranged). OK. I want GCC 4.7.1 to use the new path. Does this mean that released versions of GLIBC and GCC 4.7.1 will be incompatible, or does GLIBC pick the path up from GCC? Released versions would be incompatible (you could make GCC check at configure time for too-old glibc if --with-float=hard); the path needs hardcoding in both places. Do the MIPS or PowerPC loaders detect the ABI and change the library path based on that? I couldn't tell from the code. No, they don't detect the ABI. Both ABIs (and, for Power, the e500v1 and e500v2 variants - compatible with soft-float at the function-calling level but with some glibc ABI differences with soft-float and with each other) use the same directories. Sorry, I'm confused. I had a poke about with MIPS and it uses different argument registers for soft and hard float. Soft float uses $4 and hard float $f0. Are there shims or similar installed by the loader? No. A system is either purely hard-float or purely soft-float, and the same paths are used for both so they can't coexist. (Mismatches at *static* link time are detected through object attributes.) Ah, the same as ARM then. The MIPS community would need something similar to this patch if they wanted to support soft and hard float side by side. Big endian is extremely uncommon on ARM and I'd rather define it when needed. For strictness sake I'll change the patch to use the new path for hard float little endian only. I don't think that's correct; the new path should be used independent of endian, just as the existing path is. OK. But any multiarch support patch should presumably define separate multiarch paths for each endianness. That's up to Debian. I've asked for documentation on the final tuples and what they mean as the one at: http://wiki.debian.org/Multiarch/Tuples is out of date. I prefer defining what is needed now and doing others as needed. -- Michael
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Wed, Apr 04, 2012 at 02:39:58PM +1200, Michael Hope wrote:
On 4 April 2012 10:56, Joseph S. Myers jos...@codesourcery.com wrote:
On Tue, 3 Apr 2012, Michael Hope wrote:
+#define GLIBC_DYNAMIC_LINKER \
+ %{mhard-float: GLIBC_DYNAMIC_LINKER_HARD_FLOAT } \
+ %{mfloat-abi=hard: GLIBC_DYNAMIC_LINKER_HARD_FLOAT } \
+ %{!mfloat-abi=hard:%{!mhard-float: GLIBC_DYNAMIC_LINKER_SOFT_FLOAT
}}
(a) -mhard-float is a .opt Alias for -mfloat-abi=hard so does not need to
be handled in specs.
Fixed.
(b) You need to handle compilers configured with --with-float=hard, so
make the specs depend on the default ABI the compiler was configured with.
GCC seems to take configure time options into account when evaluating
a spec file.
Tested by building a default, --with-float=hard, and
--with-float=softfp compiler then checking the loader path for all
combinations of {,-mglibc,-mbionic,-muclibc} x
{,-mhard-float,-msoft-float,-mfloat-abi=hard,-mfloat-abi=softfp}.
(c) Please include libc-ports on future submissions and provide both the
GCC patch and the glibc ports patch that have been tested to work together
to build and install the library in the given path; a patch to one
component like this cannot sensibly be considered in isolation. I imagine
you'll need appropriate ARM preconfigure support to detect what ABI the
compiler is using, much like the support for MIPS, so that the right
shlib-versions files are used.
Agreed.
I try to follow all ARM glibc discussions
on libc-ports closely, as the ARM glibc maintainer; was there a previous
discussion of the dynamic linker naming issue there that I missed?
Steve McIntyre is driving this inside Debian. I'll ping him on the
GLIBC support.
The tricky one is new GCC with old GLIBC. GCC may have to do a
configure time test and fall back to /lib/ld-linux.so.3 if the hard
float loader is missing.
(The only previous relevant discussion that I recall is one on
patc...@eglibc.org starting at
http://www.eglibc.org/archives/patches/msg01017.html, regarding how the
dynamic linker should check that a library has the right ABI, and there
was no real followup on that after I indicated what would seem to be the
appropriate implementation approaches and places for subsequent
discussion.)
The patch above changes the loader to catch a mixed installation and
reject mixing incompatible libraries. The static linker does this
currently but it's not essential.
I have no idea whether shlib-versions files naming a file in a
subdirectory will work - but if not, you'd need to send a patch to
libc-alpha to support dynamic linkers in subdirectories, with appropriate
justification for why you are doing something different from all other
architectures.
Understood. For now this is just a path. There's more infrastructure
work needed if the path includes a directory.
(d) Existing practice for Power Architecture and MIPS at least is that
hard-float and soft-float *don't* use different library directories /
dynamic linkers.
The goal is to have a standard loader path for all hard float distros
and, similar to how you can have a mixed 32/64 bit installation, allow
mixed softfp/hard float installations for distros that want it. This
is a new requirement and ARM is the first one exposed to it. I assume
Debian would push for similar changes on MIPS and PowerPC.
Do the MIPS or PowerPC loaders detect the ABI and change the library
path based on that? I couldn't tell from the code.
(e) Existing practice for cases that do use different dynamic linkers is
to use a separate library directory, not just dynamic linker name, as in
lib32 and lib64 for MIPS or libx32 for x32; it's certainly a lot easier to
make two sets of libraries work in parallel if you have separate library
directories like that.
Is this required, or should it be left to the distro to choose? Once
the loader is in control then it can account for any distro specific
features, which may be the standard /lib and /usr/lib for single ABI
distros like Fedora or /usr/lib/$tuple for multiarch distros like
Ubuntu and Debian.
So it would seem more appropriate to define a directory libhf for ARM
(meaning you need a binutils patch as well to
handle that directory, I think)
I'd like to leave that discussion for now. The Debian goal is to
support incompatible ABIs and, past that, incompatible architectures.
libhf is ambiguous as you could have a MIPS hard float library
installed on the same system as an ARM hard float library.
and these different Debian-style names
could be implemented separately in a multiarch patch if someone submits
one that properly accounts for my review comments on previous patch
versions (failure to produce such a fixed patch being why Debian multiarch
directory support has not got into GCC so far).
Agreed. Note that this loader path discussion is unrelated
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On 4 April 2012 04:17, Andrew Haley a...@redhat.com wrote: On 04/03/2012 05:09 PM, Richard Earnshaw wrote: On 03/04/12 12:01, Jakub Jelinek wrote: On Tue, Apr 03, 2012 at 11:45:30AM +0100, Richard Earnshaw wrote: If, so then there's only one way to sort out this mess. /lib/arm-linux-gnueabi/ld-linux.so.3 Location of soft-float loader /lib/arm-linux-gnueabihf/ld-linux.so.3 Location of hard-float loader The above scheme is a Debianism which no other distro is using. Jakub Not really, it's just a naming convention for where the config-specific dynamic loader lives. It doesn't affect where the remaining shared libraries live. The subdirectories could be called fred and jim and it would still work. The only thing required is that this part of the naming scheme be agreed amongst the distros. This looks to me like it's turning into a bike-shed painting excerise between the distros out there. That's really sad. I don't think we ever even had the discussion: Debian invented their Debian-internal scheme for managing multiple ABIs. They have in the past used patched versions of gcc, as in the case of x86_64. (cc'ed cross-distro as the discussion is also going on there[1]. This patch continues that) I like the idea of incompatible binaries having different loaders. The path doesn't matter but the concept does. Like i686/x86_64, it gives distros the option to install different binaries alongside each other for compatibility, performance, or upgrade reasons. The compatibility cost is nice and low and lets Debian do some interesting cross development things. No one has released a hard float based distro yet. We have time to discuss and fix this so we don't get in the crazy situation where a third party binary only runs on some distros. -- Michael [1] http://lists.linaro.org/pipermail/cross-distro/2012-March/000135.html and http://lists.linaro.org/pipermail/cross-distro/2012-April/thread.html
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Tue, 3 Apr 2012, Michael Hope wrote:
+#define GLIBC_DYNAMIC_LINKER \
+ %{mhard-float: GLIBC_DYNAMIC_LINKER_HARD_FLOAT } \
+%{mfloat-abi=hard: GLIBC_DYNAMIC_LINKER_HARD_FLOAT } \
+%{!mfloat-abi=hard:%{!mhard-float: GLIBC_DYNAMIC_LINKER_SOFT_FLOAT }}
(a) -mhard-float is a .opt Alias for -mfloat-abi=hard so does not need to
be handled in specs.
(b) You need to handle compilers configured with --with-float=hard, so
make the specs depend on the default ABI the compiler was configured with.
(c) Please include libc-ports on future submissions and provide both the
GCC patch and the glibc ports patch that have been tested to work together
to build and install the library in the given path; a patch to one
component like this cannot sensibly be considered in isolation. I imagine
you'll need appropriate ARM preconfigure support to detect what ABI the
compiler is using, much like the support for MIPS, so that the right
shlib-versions files are used. I try to follow all ARM glibc discussions
on libc-ports closely, as the ARM glibc maintainer; was there a previous
discussion of the dynamic linker naming issue there that I missed? (The
only previous relevant discussion that I recall is one on
patc...@eglibc.org starting at
http://www.eglibc.org/archives/patches/msg01017.html, regarding how the
dynamic linker should check that a library has the right ABI, and there
was no real followup on that after I indicated what would seem to be the
appropriate implementation approaches and places for subsequent
discussion.)
I have no idea whether shlib-versions files naming a file in a
subdirectory will work - but if not, you'd need to send a patch to
libc-alpha to support dynamic linkers in subdirectories, with appropriate
justification for why you are doing something different from all other
architectures.
(d) Existing practice for Power Architecture and MIPS at least is that
hard-float and soft-float *don't* use different library directories /
dynamic linkers.
(e) Existing practice for cases that do use different dynamic linkers is
to use a separate library directory, not just dynamic linker name, as in
lib32 and lib64 for MIPS or libx32 for x32; it's certainly a lot easier to
make two sets of libraries work in parallel if you have separate library
directories like that. So it would seem more appropriate to define a
directory libhf for ARM (meaning you need a binutils patch as well to
handle that directory, I think), and these different Debian-style names
could be implemented separately in a multiarch patch if someone submits
one that properly accounts for my review comments on previous patch
versions (failure to produce such a fixed patch being why Debian multiarch
directory support has not got into GCC so far).
--
Joseph S. Myers
jos...@codesourcery.com
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Wed, Apr 04, 2012 at 09:18:59AM +1200, Michael Hope wrote: The subdirectories could be called fred and jim and it would still work. The only thing required is that this part of the naming scheme be agreed amongst the distros. This looks to me like it's turning into a bike-shed painting excerise between the distros out there. That's really sad. I don't think we ever even had the discussion: Debian invented their Debian-internal scheme for managing multiple ABIs. They have in the past used patched versions of gcc, as in the case of x86_64. (cc'ed cross-distro as the discussion is also going on there[1]. This patch continues that) I like the idea of incompatible binaries having different loaders. The path doesn't matter but the concept does. Like i686/x86_64, it gives distros the option to install different binaries alongside each other for compatibility, performance, or upgrade reasons. The compatibility cost is nice and low and lets Debian do some interesting cross development things. Does the dynamic linker itself contain any routines that depend on the soft/hard ABI? That would quite surprise me, so I don't see the point of having different dynamic linkers for those ABIs. One dynamic linker should handle both just fine. No one has released a hard float based distro yet. We have time to discuss and fix this so we don't get in the crazy situation where a third party binary only runs on some distros. Isn't e.g. Fedora 17/armv7hl a hard float based distro? Jakub
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
Em 3 de abril de 2012 20:48, Michael Hope michael.h...@linaro.org escreveu: On 4 April 2012 11:11, Jakub Jelinek ja...@redhat.com wrote: On Wed, Apr 04, 2012 at 09:18:59AM +1200, Michael Hope wrote: The subdirectories could be called fred and jim and it would still work. The only thing required is that this part of the naming scheme be agreed amongst the distros. This looks to me like it's turning into a bike-shed painting excerise between the distros out there. That's really sad. I don't think we ever even had the discussion: Debian invented their Debian-internal scheme for managing multiple ABIs. They have in the past used patched versions of gcc, as in the case of x86_64. (cc'ed cross-distro as the discussion is also going on there[1]. This patch continues that) I like the idea of incompatible binaries having different loaders. The path doesn't matter but the concept does. Like i686/x86_64, it gives distros the option to install different binaries alongside each other for compatibility, performance, or upgrade reasons. The compatibility cost is nice and low and lets Debian do some interesting cross development things. Does the dynamic linker itself contain any routines that depend on the soft/hard ABI? That would quite surprise me, so I don't see the point of having different dynamic linkers for those ABIs. One dynamic linker should handle both just fine. No one has released a hard float based distro yet. We have time to discuss and fix this so we don't get in the crazy situation where a third party binary only runs on some distros. Isn't e.g. Fedora 17/armv7hl a hard float based distro? Yip, as is Ubuntu Precise, Debian unstable, and a skew of Gentoo. None have been released yet. Here's my understanding: Fedora 17: * ARM is a secondary architecture * Alpha 1 release is out * Has both a ARMv5 soft float and ARMv7 hard float build Ubuntu Precise: * ARM is a primary architecture * Beta 2 is out * ARMv7 hard float by default with ARMv7 softfp being community supported Debian: * ARM is a primary architecture * Has a ARMv4T soft float and in-development ARMv7 hard float openSUSE: * Kicked off at a hackfest in September 2011 * Have a ARMv5T soft float and ARMv7 hard float build Gentoo: * I'm unsure (help?) * The Gentoo manual suggests ARMv7 softfp is the default I did two ports of Mandriva to armv7. One of my choice to use softfp, and another hardfp port to be compatible with other distros. But other than a previous armv5 port, there is not much else of Mandriva arm, so, it would be good to have to be able to run binaries for either without resorting to a chroot, and only testing purposes. Bumping major or calling it ld-linux-foo.so.3 is out of question? -- Michael ___ cross-distro mailing list cross-dis...@lists.linaro.org http://lists.linaro.org/mailman/listinfo/cross-distro Paulo
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
2012/4/4 Paulo César Pereira de Andrade paulo.cesar.pereira.de.andr...@gmail.com: Em 3 de abril de 2012 20:48, Michael Hope michael.h...@linaro.org escreveu: snip Yip, as is Ubuntu Precise, Debian unstable, and a skew of Gentoo. None have been released yet. Here's my understanding: Fedora 17: * ARM is a secondary architecture * Alpha 1 release is out * Has both a ARMv5 soft float and ARMv7 hard float build Ubuntu Precise: * ARM is a primary architecture * Beta 2 is out * ARMv7 hard float by default with ARMv7 softfp being community supported Debian: * ARM is a primary architecture * Has a ARMv4T soft float and in-development ARMv7 hard float openSUSE: * Kicked off at a hackfest in September 2011 * Have a ARMv5T soft float and ARMv7 hard float build Gentoo: * I'm unsure (help?) * The Gentoo manual suggests ARMv7 softfp is the default I did two ports of Mandriva to armv7. One of my choice to use softfp, and another hardfp port to be compatible with other distros. But other than a previous armv5 port, there is not much else of Mandriva arm, so, it would be good to have to be able to run binaries for either without resorting to a chroot, and only testing purposes. Bumping major or calling it ld-linux-foo.so.3 is out of question? I suspect /lib/ld-linux-$foo.so.3 would be fine. There's two questions here though: can the hard float loader have a different path and, if so, what should it be? We're still working on the first part. -- Michael
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On 4 April 2012 10:56, Joseph S. Myers jos...@codesourcery.com wrote:
On Tue, 3 Apr 2012, Michael Hope wrote:
+#define GLIBC_DYNAMIC_LINKER \
+ %{mhard-float: GLIBC_DYNAMIC_LINKER_HARD_FLOAT } \
+ %{mfloat-abi=hard: GLIBC_DYNAMIC_LINKER_HARD_FLOAT } \
+ %{!mfloat-abi=hard:%{!mhard-float: GLIBC_DYNAMIC_LINKER_SOFT_FLOAT }}
(a) -mhard-float is a .opt Alias for -mfloat-abi=hard so does not need to
be handled in specs.
Fixed.
(b) You need to handle compilers configured with --with-float=hard, so
make the specs depend on the default ABI the compiler was configured with.
GCC seems to take configure time options into account when evaluating
a spec file.
Tested by building a default, --with-float=hard, and
--with-float=softfp compiler then checking the loader path for all
combinations of {,-mglibc,-mbionic,-muclibc} x
{,-mhard-float,-msoft-float,-mfloat-abi=hard,-mfloat-abi=softfp}.
(c) Please include libc-ports on future submissions and provide both the
GCC patch and the glibc ports patch that have been tested to work together
to build and install the library in the given path; a patch to one
component like this cannot sensibly be considered in isolation. I imagine
you'll need appropriate ARM preconfigure support to detect what ABI the
compiler is using, much like the support for MIPS, so that the right
shlib-versions files are used.
Agreed.
I try to follow all ARM glibc discussions
on libc-ports closely, as the ARM glibc maintainer; was there a previous
discussion of the dynamic linker naming issue there that I missed?
Steve McIntyre is driving this inside Debian. I'll ping him on the
GLIBC support.
The tricky one is new GCC with old GLIBC. GCC may have to do a
configure time test and fall back to /lib/ld-linux.so.3 if the hard
float loader is missing.
(The only previous relevant discussion that I recall is one on
patc...@eglibc.org starting at
http://www.eglibc.org/archives/patches/msg01017.html, regarding how the
dynamic linker should check that a library has the right ABI, and there
was no real followup on that after I indicated what would seem to be the
appropriate implementation approaches and places for subsequent
discussion.)
The patch above changes the loader to catch a mixed installation and
reject mixing incompatible libraries. The static linker does this
currently but it's not essential.
I have no idea whether shlib-versions files naming a file in a
subdirectory will work - but if not, you'd need to send a patch to
libc-alpha to support dynamic linkers in subdirectories, with appropriate
justification for why you are doing something different from all other
architectures.
Understood. For now this is just a path. There's more infrastructure
work needed if the path includes a directory.
(d) Existing practice for Power Architecture and MIPS at least is that
hard-float and soft-float *don't* use different library directories /
dynamic linkers.
The goal is to have a standard loader path for all hard float distros
and, similar to how you can have a mixed 32/64 bit installation, allow
mixed softfp/hard float installations for distros that want it. This
is a new requirement and ARM is the first one exposed to it. I assume
Debian would push for similar changes on MIPS and PowerPC.
Do the MIPS or PowerPC loaders detect the ABI and change the library
path based on that? I couldn't tell from the code.
(e) Existing practice for cases that do use different dynamic linkers is
to use a separate library directory, not just dynamic linker name, as in
lib32 and lib64 for MIPS or libx32 for x32; it's certainly a lot easier to
make two sets of libraries work in parallel if you have separate library
directories like that.
Is this required, or should it be left to the distro to choose? Once
the loader is in control then it can account for any distro specific
features, which may be the standard /lib and /usr/lib for single ABI
distros like Fedora or /usr/lib/$tuple for multiarch distros like
Ubuntu and Debian.
So it would seem more appropriate to define a directory libhf for ARM
(meaning you need a binutils patch as well to
handle that directory, I think)
I'd like to leave that discussion for now. The Debian goal is to
support incompatible ABIs and, past that, incompatible architectures.
libhf is ambiguous as you could have a MIPS hard float library
installed on the same system as an ARM hard float library.
and these different Debian-style names
could be implemented separately in a multiarch patch if someone submits
one that properly accounts for my review comments on previous patch
versions (failure to produce such a fixed patch being why Debian multiarch
directory support has not got into GCC so far).
Agreed. Note that this loader path discussion is unrelated to
multiarch. It came from the same people so there's a family
resemblance.
(BTW Dann, apologies for stealing your patch)
-- Michael
2012-04-03 Michael Hope
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On 04/02/2012 10:06 PM, dann frazier wrote:
On Fri, Mar 30, 2012 at 06:52:34PM +0100, Richard Earnshaw wrote:
On 29/03/12 20:34, dann frazier wrote:
This is an updated version of a patch Debian and Ubuntu are using to
use an alternate linker path for hardfloat binaries. The difference
with this one is that it covers the case where no float flag
was passed in, defaulting to the softfloat path.
2012-03-29 dann frazier dann.fraz...@canonical.com
* config/arm/linux-elf.h: Use alternate linker path
for hardfloat ABI
Index: gcc/config/arm/linux-elf.h
===
--- gcc/config/arm/linux-elf.h (revision 185708)
+++ gcc/config/arm/linux-elf.h (working copy)
@@ -59,14 +59,21 @@
#define LIBGCC_SPEC %{mfloat-abi=soft*:-lfloat} -lgcc
-#define GLIBC_DYNAMIC_LINKER /lib/ld-linux.so.2
+#define LINUX_DYNAMIC_LINKER_SF /lib/ld-linux.so.3
+#define LINUX_DYNAMIC_LINKER_HF /lib/arm-linux-gnueabihf/ld-linux.so.3
#define LINUX_TARGET_LINK_SPEC %{h*} \
%{static:-Bstatic} \
%{shared:-shared} \
%{symbolic:-Bsymbolic} \
%{rdynamic:-export-dynamic} \
- -dynamic-linker GNU_USER_DYNAMIC_LINKER \
+ %{msoft-float:-dynamic-linker LINUX_DYNAMIC_LINKER_SF } \
+ %{mfloat-abi=soft*:-dynamic-linker LINUX_DYNAMIC_LINKER_SF } \
+ %{mhard-float:-dynamic-linker LINUX_DYNAMIC_LINKER_HF } \
+ %{mfloat-abi=hard:-dynamic-linker LINUX_DYNAMIC_LINKER_HF } \
+ %{!mfloat-abi: \
+ %{!msoft-float: \
+ %{!mhard-float:-dynamic-linker LINUX_DYNAMIC_LINKER_SF }}} \
-X \
%{mbig-endian:-EB} %{mlittle-endian:-EL} \
SUBTARGET_EXTRA_LINK_SPEC
Looks to me as though this will break the old Linux ABI. While we've
marked that as deprecated, it hasn't been removed as yet. So I think
this patch either needs to wait until that removal has taken place, or
provide the relevant updates to maintain the old ABI support.
Thanks for your review. You're right, this does appear to break the
old ABI - that was a misunderstanding on my part. I think this fixes
the problem:
But what about those of us who are using hard-float but not the
Debian liker path? It'll break, surely. This looks to be like
it's Debian-specific.
Andrew.
Index: gcc/config/arm/linux-elf.h
===
--- gcc/config/arm/linux-elf.h(revision 185708)
+++ gcc/config/arm/linux-elf.h(working copy)
@@ -60,13 +60,17 @@
#define LIBGCC_SPEC %{mfloat-abi=soft*:-lfloat} -lgcc
#define GLIBC_DYNAMIC_LINKER /lib/ld-linux.so.2
+#define LINUX_DYNAMIC_LINKER_HF /lib/arm-linux-gnueabihf/ld-linux.so.3
#define LINUX_TARGET_LINK_SPEC %{h*} \
%{static:-Bstatic} \
%{shared:-shared} \
%{symbolic:-Bsymbolic} \
%{rdynamic:-export-dynamic} \
- -dynamic-linker GNU_USER_DYNAMIC_LINKER \
+ %{mhard-float:-dynamic-linker LINUX_DYNAMIC_LINKER_HF } \
+ %{mfloat-abi=hard:-dynamic-linker LINUX_DYNAMIC_LINKER_HF } \
+ %{!mfloat-abi: \
+ %{!mhard-float:-dynamic-linker GNU_USER_DYNAMIC_LINKER }} \
-X \
%{mbig-endian:-EB} %{mlittle-endian:-EL} \
SUBTARGET_EXTRA_LINK_SPEC
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Tue, Apr 03, 2012 at 11:45:30AM +0100, Richard Earnshaw wrote: If, so then there's only one way to sort out this mess. /lib/arm-linux-gnueabi/ld-linux.so.3 Location of soft-float loader /lib/arm-linux-gnueabihf/ld-linux.so.3 Location of hard-float loader The above scheme is a Debianism which no other distro is using. Jakub
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Tue, Apr 03, 2012 at 03:29:06PM +1200, Michael Hope wrote:
On 3 April 2012 09:06, dann frazier dann.fraz...@canonical.com wrote:
On Fri, Mar 30, 2012 at 06:52:34PM +0100, Richard Earnshaw wrote:
On 29/03/12 20:34, dann frazier wrote:
This is an updated version of a patch Debian and Ubuntu are using to
use an alternate linker path for hardfloat binaries. The difference
with this one is that it covers the case where no float flag
was passed in, defaulting to the softfloat path.
Hi Dann. The change should be in the EABI specific linux-eabi.h
instead of the shared/OABI linux-elf.h. It breaks support for uClibc
and Bionic by always using the GLIBC loader in hard float mode. The
final line in the spec is missing a '=hard' and always adds
/lib/ld-linux.so.3.
How about:
2012-04-03 Michael Hope michael.h...@linaro.org
* config/arm/linux-eabi.h (GLIBC_DYNAMIC_LINKER_HARD_FLOAT): Define.
(GLIBC_DYNAMIC_LINKER): Redefine to use the hard float loader.
Nice, thanks Michael. I'd looked at doing something similar, but I
wasn't sure that defining GLIBC_DYNAMIC_LINKER to a spec macro would
work :)
-dann
diff --git a/gcc/config/arm/linux-eabi.h b/gcc/config/arm/linux-eabi.h
index 80bd825..8498472 100644
--- a/gcc/config/arm/linux-eabi.h
+++ b/gcc/config/arm/linux-eabi.h
@@ -62,7 +62,12 @@
/* Use ld-linux.so.3 so that it will be possible to run classic
GNU/Linux binaries on an EABI system. */
#undef GLIBC_DYNAMIC_LINKER
-#define GLIBC_DYNAMIC_LINKER /lib/ld-linux.so.3
+#define GLIBC_DYNAMIC_LINKER_SOFT_FLOAT /lib/ld-linux.so.3
+#define GLIBC_DYNAMIC_LINKER_HARD_FLOAT
/lib/arm-linux-gnueabihf/ld-linux.so.3
+#define GLIBC_DYNAMIC_LINKER \
+ %{mhard-float: GLIBC_DYNAMIC_LINKER_HARD_FLOAT } \
+%{mfloat-abi=hard: GLIBC_DYNAMIC_LINKER_HARD_FLOAT } \
+%{!mfloat-abi=hard:%{!mhard-float: GLIBC_DYNAMIC_LINKER_SOFT_FLOAT }}
/* At this point, bpabi.h will have clobbered LINK_SPEC. We want to
use the GNU/Linux version, not the generic BPABI version. */
which works for the following test cases:
gcc -mhard-float foo.c = /lib/arm-linux-gnueabihf/ld-linux.so.3
gcc -mfloat-abi=hard foo.c = /lib/arm-linux-gnueabihf/ld-linux.so.3
gcc -msoft-float foo.c = /lib/ld-linux.so.3
gcc -mfloat-abi=softfp foo.c = /lib/ld-linux.so.3
gcc -mbionic = /system/bin/linker
gcc -mbionic -mhard-float = /system/bin/linker
gcc -muclibc = /lib/ld-uClibc.so.0
gcc -muclibc -mhard-float = /lib/ld-uClibc.so.0
-- Michael
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On 03/04/12 12:01, Jakub Jelinek wrote: On Tue, Apr 03, 2012 at 11:45:30AM +0100, Richard Earnshaw wrote: If, so then there's only one way to sort out this mess. /lib/arm-linux-gnueabi/ld-linux.so.3 Location of soft-float loader /lib/arm-linux-gnueabihf/ld-linux.so.3 Location of hard-float loader The above scheme is a Debianism which no other distro is using. Jakub Not really, it's just a naming convention for where the config-specific dynamic loader lives. It doesn't affect where the remaining shared libraries live. The subdirectories could be called fred and jim and it would still work. The only thing required is that this part of the naming scheme be agreed amongst the distros. This looks to me like it's turning into a bike-shed painting excerise between the distros out there. That's really sad. R.
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On 04/03/2012 05:09 PM, Richard Earnshaw wrote: On 03/04/12 12:01, Jakub Jelinek wrote: On Tue, Apr 03, 2012 at 11:45:30AM +0100, Richard Earnshaw wrote: If, so then there's only one way to sort out this mess. /lib/arm-linux-gnueabi/ld-linux.so.3 Location of soft-float loader /lib/arm-linux-gnueabihf/ld-linux.so.3 Location of hard-float loader The above scheme is a Debianism which no other distro is using. Jakub Not really, it's just a naming convention for where the config-specific dynamic loader lives. It doesn't affect where the remaining shared libraries live. The subdirectories could be called fred and jim and it would still work. The only thing required is that this part of the naming scheme be agreed amongst the distros. This looks to me like it's turning into a bike-shed painting excerise between the distros out there. That's really sad. I don't think we ever even had the discussion: Debian invented their Debian-internal scheme for managing multiple ABIs. They have in the past used patched versions of gcc, as in the case of x86_64. Andrew.
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On Fri, Mar 30, 2012 at 06:52:34PM +0100, Richard Earnshaw wrote:
On 29/03/12 20:34, dann frazier wrote:
This is an updated version of a patch Debian and Ubuntu are using to
use an alternate linker path for hardfloat binaries. The difference
with this one is that it covers the case where no float flag
was passed in, defaulting to the softfloat path.
2012-03-29 dann frazier dann.fraz...@canonical.com
* config/arm/linux-elf.h: Use alternate linker path
for hardfloat ABI
Index: gcc/config/arm/linux-elf.h
===
--- gcc/config/arm/linux-elf.h (revision 185708)
+++ gcc/config/arm/linux-elf.h (working copy)
@@ -59,14 +59,21 @@
#define LIBGCC_SPEC %{mfloat-abi=soft*:-lfloat} -lgcc
-#define GLIBC_DYNAMIC_LINKER /lib/ld-linux.so.2
+#define LINUX_DYNAMIC_LINKER_SF /lib/ld-linux.so.3
+#define LINUX_DYNAMIC_LINKER_HF /lib/arm-linux-gnueabihf/ld-linux.so.3
#define LINUX_TARGET_LINK_SPEC %{h*} \
%{static:-Bstatic} \
%{shared:-shared} \
%{symbolic:-Bsymbolic} \
%{rdynamic:-export-dynamic} \
- -dynamic-linker GNU_USER_DYNAMIC_LINKER \
+ %{msoft-float:-dynamic-linker LINUX_DYNAMIC_LINKER_SF } \
+ %{mfloat-abi=soft*:-dynamic-linker LINUX_DYNAMIC_LINKER_SF } \
+ %{mhard-float:-dynamic-linker LINUX_DYNAMIC_LINKER_HF } \
+ %{mfloat-abi=hard:-dynamic-linker LINUX_DYNAMIC_LINKER_HF } \
+ %{!mfloat-abi: \
+ %{!msoft-float: \
+ %{!mhard-float:-dynamic-linker LINUX_DYNAMIC_LINKER_SF }}} \
-X \
%{mbig-endian:-EB} %{mlittle-endian:-EL} \
SUBTARGET_EXTRA_LINK_SPEC
Looks to me as though this will break the old Linux ABI. While we've
marked that as deprecated, it hasn't been removed as yet. So I think
this patch either needs to wait until that removal has taken place, or
provide the relevant updates to maintain the old ABI support.
Thanks for your review. You're right, this does appear to break the
old ABI - that was a misunderstanding on my part. I think this fixes
the problem:
Index: gcc/config/arm/linux-elf.h
===
--- gcc/config/arm/linux-elf.h (revision 185708)
+++ gcc/config/arm/linux-elf.h (working copy)
@@ -60,13 +60,17 @@
#define LIBGCC_SPEC %{mfloat-abi=soft*:-lfloat} -lgcc
#define GLIBC_DYNAMIC_LINKER /lib/ld-linux.so.2
+#define LINUX_DYNAMIC_LINKER_HF /lib/arm-linux-gnueabihf/ld-linux.so.3
#define LINUX_TARGET_LINK_SPEC %{h*} \
%{static:-Bstatic} \
%{shared:-shared} \
%{symbolic:-Bsymbolic} \
%{rdynamic:-export-dynamic} \
- -dynamic-linker GNU_USER_DYNAMIC_LINKER \
+ %{mhard-float:-dynamic-linker LINUX_DYNAMIC_LINKER_HF } \
+ %{mfloat-abi=hard:-dynamic-linker LINUX_DYNAMIC_LINKER_HF } \
+ %{!mfloat-abi: \
+ %{!mhard-float:-dynamic-linker GNU_USER_DYNAMIC_LINKER }} \
-X \
%{mbig-endian:-EB} %{mlittle-endian:-EL} \
SUBTARGET_EXTRA_LINK_SPEC
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On 3 April 2012 09:06, dann frazier dann.fraz...@canonical.com wrote:
On Fri, Mar 30, 2012 at 06:52:34PM +0100, Richard Earnshaw wrote:
On 29/03/12 20:34, dann frazier wrote:
This is an updated version of a patch Debian and Ubuntu are using to
use an alternate linker path for hardfloat binaries. The difference
with this one is that it covers the case where no float flag
was passed in, defaulting to the softfloat path.
Hi Dann. The change should be in the EABI specific linux-eabi.h
instead of the shared/OABI linux-elf.h. It breaks support for uClibc
and Bionic by always using the GLIBC loader in hard float mode. The
final line in the spec is missing a '=hard' and always adds
/lib/ld-linux.so.3.
How about:
2012-04-03 Michael Hope michael.h...@linaro.org
* config/arm/linux-eabi.h (GLIBC_DYNAMIC_LINKER_HARD_FLOAT): Define.
(GLIBC_DYNAMIC_LINKER): Redefine to use the hard float loader.
diff --git a/gcc/config/arm/linux-eabi.h b/gcc/config/arm/linux-eabi.h
index 80bd825..8498472 100644
--- a/gcc/config/arm/linux-eabi.h
+++ b/gcc/config/arm/linux-eabi.h
@@ -62,7 +62,12 @@
/* Use ld-linux.so.3 so that it will be possible to run classic
GNU/Linux binaries on an EABI system. */
#undef GLIBC_DYNAMIC_LINKER
-#define GLIBC_DYNAMIC_LINKER /lib/ld-linux.so.3
+#define GLIBC_DYNAMIC_LINKER_SOFT_FLOAT /lib/ld-linux.so.3
+#define GLIBC_DYNAMIC_LINKER_HARD_FLOAT
/lib/arm-linux-gnueabihf/ld-linux.so.3
+#define GLIBC_DYNAMIC_LINKER \
+ %{mhard-float: GLIBC_DYNAMIC_LINKER_HARD_FLOAT } \
+%{mfloat-abi=hard: GLIBC_DYNAMIC_LINKER_HARD_FLOAT } \
+%{!mfloat-abi=hard:%{!mhard-float: GLIBC_DYNAMIC_LINKER_SOFT_FLOAT }}
/* At this point, bpabi.h will have clobbered LINK_SPEC. We want to
use the GNU/Linux version, not the generic BPABI version. */
which works for the following test cases:
gcc -mhard-float foo.c = /lib/arm-linux-gnueabihf/ld-linux.so.3
gcc -mfloat-abi=hard foo.c = /lib/arm-linux-gnueabihf/ld-linux.so.3
gcc -msoft-float foo.c = /lib/ld-linux.so.3
gcc -mfloat-abi=softfp foo.c = /lib/ld-linux.so.3
gcc -mbionic = /system/bin/linker
gcc -mbionic -mhard-float = /system/bin/linker
gcc -muclibc = /lib/ld-uClibc.so.0
gcc -muclibc -mhard-float = /lib/ld-uClibc.so.0
-- Michael
Re: [PATCH] ARM: Use different linker path for hardfloat ABI
On 29/03/12 20:34, dann frazier wrote:
This is an updated version of a patch Debian and Ubuntu are using to
use an alternate linker path for hardfloat binaries. The difference
with this one is that it covers the case where no float flag
was passed in, defaulting to the softfloat path.
2012-03-29 dann frazier dann.fraz...@canonical.com
* config/arm/linux-elf.h: Use alternate linker path
for hardfloat ABI
Index: gcc/config/arm/linux-elf.h
===
--- gcc/config/arm/linux-elf.h(revision 185708)
+++ gcc/config/arm/linux-elf.h(working copy)
@@ -59,14 +59,21 @@
#define LIBGCC_SPEC %{mfloat-abi=soft*:-lfloat} -lgcc
-#define GLIBC_DYNAMIC_LINKER /lib/ld-linux.so.2
+#define LINUX_DYNAMIC_LINKER_SF /lib/ld-linux.so.3
+#define LINUX_DYNAMIC_LINKER_HF /lib/arm-linux-gnueabihf/ld-linux.so.3
#define LINUX_TARGET_LINK_SPEC %{h*} \
%{static:-Bstatic} \
%{shared:-shared} \
%{symbolic:-Bsymbolic} \
%{rdynamic:-export-dynamic} \
- -dynamic-linker GNU_USER_DYNAMIC_LINKER \
+ %{msoft-float:-dynamic-linker LINUX_DYNAMIC_LINKER_SF } \
+ %{mfloat-abi=soft*:-dynamic-linker LINUX_DYNAMIC_LINKER_SF } \
+ %{mhard-float:-dynamic-linker LINUX_DYNAMIC_LINKER_HF } \
+ %{mfloat-abi=hard:-dynamic-linker LINUX_DYNAMIC_LINKER_HF } \
+ %{!mfloat-abi: \
+ %{!msoft-float: \
+ %{!mhard-float:-dynamic-linker LINUX_DYNAMIC_LINKER_SF }}} \
-X \
%{mbig-endian:-EB} %{mlittle-endian:-EL} \
SUBTARGET_EXTRA_LINK_SPEC
Looks to me as though this will break the old Linux ABI. While we've
marked that as deprecated, it hasn't been removed as yet. So I think
this patch either needs to wait until that removal has taken place, or
provide the relevant updates to maintain the old ABI support.
R.
[PATCH] ARM: Use different linker path for hardfloat ABI
This is an updated version of a patch Debian and Ubuntu are using to
use an alternate linker path for hardfloat binaries. The difference
with this one is that it covers the case where no float flag
was passed in, defaulting to the softfloat path.
2012-03-29 dann frazier dann.fraz...@canonical.com
* config/arm/linux-elf.h: Use alternate linker path
for hardfloat ABI
Index: gcc/config/arm/linux-elf.h
===
--- gcc/config/arm/linux-elf.h (revision 185708)
+++ gcc/config/arm/linux-elf.h (working copy)
@@ -59,14 +59,21 @@
#define LIBGCC_SPEC %{mfloat-abi=soft*:-lfloat} -lgcc
-#define GLIBC_DYNAMIC_LINKER /lib/ld-linux.so.2
+#define LINUX_DYNAMIC_LINKER_SF /lib/ld-linux.so.3
+#define LINUX_DYNAMIC_LINKER_HF /lib/arm-linux-gnueabihf/ld-linux.so.3
#define LINUX_TARGET_LINK_SPEC %{h*} \
%{static:-Bstatic} \
%{shared:-shared} \
%{symbolic:-Bsymbolic} \
%{rdynamic:-export-dynamic} \
- -dynamic-linker GNU_USER_DYNAMIC_LINKER \
+ %{msoft-float:-dynamic-linker LINUX_DYNAMIC_LINKER_SF } \
+ %{mfloat-abi=soft*:-dynamic-linker LINUX_DYNAMIC_LINKER_SF } \
+ %{mhard-float:-dynamic-linker LINUX_DYNAMIC_LINKER_HF } \
+ %{mfloat-abi=hard:-dynamic-linker LINUX_DYNAMIC_LINKER_HF } \
+ %{!mfloat-abi: \
+ %{!msoft-float: \
+ %{!mhard-float:-dynamic-linker LINUX_DYNAMIC_LINKER_SF }}} \
-X \
%{mbig-endian:-EB} %{mlittle-endian:-EL} \
SUBTARGET_EXTRA_LINK_SPEC
