Re: Intrepid compatibility with C3 CPUs #5212
Colin Watson wrote: On Thu, Aug 21, 2008 at 01:49:27AM -0400, M G wrote: Subject: Intrepid compatibility with C3 CPUs #5212 Are you referring to a particular bug here? https://launchpad.net/bugs/5212 is something quite different. MG's message got detached from the start of the thread. if you do a title search for C3 through the devel-discuss you will fine the start, from me on 20080818 the bug is https://bugs.launchpad.net/ubuntu/+source/linux/+bug/254453 Thanks Sam Tygier -- Ubuntu-devel-discuss mailing list Ubuntu-devel-discuss@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-devel-discuss
Re: Intrepid compatibility with C3 CPUs #5212
On Mon, Sep 01, 2008 at 08:18:18AM +0100, Sam Tygier wrote: Colin Watson wrote: On Thu, Aug 21, 2008 at 01:49:27AM -0400, M G wrote: Subject: Intrepid compatibility with C3 CPUs #5212 Are you referring to a particular bug here? https://launchpad.net/bugs/5212 is something quite different. MG's message got detached from the start of the thread. if you do a title search for C3 through the devel-discuss you will fine the start, from me on 20080818 the bug is https://bugs.launchpad.net/ubuntu/+source/linux/+bug/254453 Thanks. I've updated the bug to note that it should be fixed in 2.6.27 and to ask for feedback. This bug report also clarifies that please use a kernel appropriate for your CPU is in fact an error message produced by the kernel and not (as I thought) a message produced by the installer, so please disregard my previous request to file a bug on base-installer with /proc/cpuinfo attached. -- Colin Watson [EMAIL PROTECTED] -- Ubuntu-devel-discuss mailing list Ubuntu-devel-discuss@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-devel-discuss
Re: Intrepid compatibility with C3 CPUs #5212
On Thu, Aug 21, 2008 at 01:49:27AM -0400, M G wrote: Subject: Intrepid compatibility with C3 CPUs #5212 Are you referring to a particular bug here? https://launchpad.net/bugs/5212 is something quite different. The C3 is still listed as a current product on the Via web site. However, if Wikipedia can be trusted, then not all C3 processors are the same when it comes to cmov support. The CPU flags have to be examined to see if a particular generation of C3 model supports cmov or not. The problem also may not be simply the C3. There are other low power CPUs that may also be affected (e.g. Geode). Is this a problem you're encountering personally? On what release of Ubuntu are you encountering it? The reason I ask is that I thought we already took some care to avoid cmov, precisely because of this problem. In fact, before Ubuntu went public, we had to purge the archive and rebuild it from scratch because we realised that the use of cmov meant we wouldn't work on many C3 CPUs. To look at the problem in general though, there are several issues which must be considered. 1) The Intrepid 32 bit kernel describes itself as i386 (intrepid-desktop-i386.iso). This is clearly incorrect and misleading. i386 is the architecture identifier, and cannot be changed (well, not without an absurd amount of effort and creating other problems). I don't propose to make the CD image file name not match the architecture name because that would also be confusing to a different set of people. Furthermore, i386 is only visible in the file name. The *description* reads as follows: PC (Intel x86) desktop CD For almost all PCs. This includes most machines with Intel/AMD/etc type processors and almost all computers that run Microsoft Windows, as well as newer Apple Macintosh systems based on Intel processors. Choose this if you are at all unsure. 2) The download page states Choose this if you are at all unsure. This is also clearly incorrect. Someone attempting to use this version must be absolutely sure what CPU they have, and possibly even the exact version. If you can't run the i386 CD (and you aren't using something other than a PC, like a pre-Intel Apple Mac or a SPARC; those people generally know what they've got), then no other Ubuntu image is going to work for you. As such I think the clear this is what to do if the rest of the page is just so much jargon to you is entirely appropriate. 3) The error message from the installer is unhelpful. It asks the user to please use a kernel appropriate for your CPU, yet there is no hint as to where this kernel may be found. What is the user supposed to do at this point? If the user gets that message, there is nothing they can do except report a bug (like many other installation problems). Speaking of which, are you encountering this message? Please file a bug report here: https://bugs.launchpad.net/ubuntu/+source/base-installer/+filebug I'll need you to attach the contents of /proc/cpuinfo to your bug report. (The rest of your message implies that you currently have Ubuntu running on this machine, so you should be able to use that to get at /proc/cpuinfo.) 4) Making this change will cause PCs which currently use Ubuntu to no longer be able to do so. 5) Making this change will limit the hardware compatibility in ways which very few users (even very technically inclined ones) would expect. I believe the change you're referring to here is that the Intrepid i386 -generic kernel started being compiled with CONFIG_M686 rather than the previous CONFIG_M586. When I heard about this change, I raised it with the kernel team manager (since we happened to be in the same room at the time), who IIRC said that this was a mistake and was not intentional. It appears to be fixed in the Intrepid 2.6.27 kernels. However, this won't help the installer problem you seem to be having; for that, I need a bug report with that information I mentioned above. The latter two items are the serious problems. Dropping users and dropping support for basic hardware isn't a decision to be made lightly, and it certainly shouldn't be made quietly by a few people and sprung on everyone else by surprise as a fait acompli. It's something that should be discussed more widely with respect to what markets are being served and what the overall support strategy should be. If I'm understanding your message correctly, I think you're elevating a mistake to the status of a major decision. :-) There are basically two types of x86 Ubuntu offered at present - 32 bit and 64 bit. Most new CPUs sold today are 64 bit, so that is where the future of Ubuntu ought to be. 32 bit is for older (legacy) hardware or for specialised uses such as low power or embedded applications. In other words, 64 bit is for mainstream desktops, laptops and servers and 32 bit is for legacy and special purpose. Without wishing to disagree with your conclusion, I think this premise is mistaken
Future of IA32 (Was: Intrepid compatibility with C3 CPUs #5212)
M G wrote: There are basically two types of x86 Ubuntu offered at present - 32 bit and 64 bit. Most new CPUs sold today are 64 bit, so that is where the future of Ubuntu ought to be. 32 bit is for older (legacy) hardware or for specialised uses such as low power or embedded applications. In other words, 64 bit is for mainstream desktops, laptops and servers and 32 bit is for legacy and special purpose. If this is a correct way of looking at things, then it doesn't make much sense to exclude support for some 32 bit processors, nor does it make sense to come out with a special third version (x86-64, i686, i586) to handle these cases. Rather I think it would make more sense to leave CPU support in 8.10 the same as it was in 8.04 (C3 works). Time will solve this problem anyway as 32 bit simply fades away. Without discussion of the temporary issue regarding support for i586-class machines (now apparently solved), I'd like to specifically dispute that 32-bit processors are going to fade away any time soon. There are an increasing number of 32-bit only IA32 processors coming on the market, with generally smaller footprints in the interest of reducing power usage. While there are a few processors that are in this class, the most well advertised currently is the Atom processor from Intel. Until such time as we cannot reasonably expect a system to operate cleanly with only two gigabytes of memory, there exists a useful niche for such processors (and the Atom is actually limited to one gigabyte of memory). As Ubuntu currently well capable of installing and running on systems with 256MB RAM, and there are scattered reports of working systems with as little as 64MB RAM, I expect that this time will be at least a decade hence, and so not relevant to current discussions. -- Emmet HIKORY -- Ubuntu-devel-discuss mailing list Ubuntu-devel-discuss@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-devel-discuss
Intrepid compatibility with C3 CPUs #5212
The C3 is still listed as a current product on the Via web site. However, if Wikipedia can be trusted, then not all C3 processors are the same when it comes to cmov support. The CPU flags have to be examined to see if a particular generation of C3 model supports cmov or not. The problem also may not be simply the C3. There are other low power CPUs that may also be affected (e.g. Geode). To look at the problem in general though, there are several issues which must be considered. 1) The Intrepid 32 bit kernel describes itself as i386 (intrepid-desktop-i386.iso). This is clearly incorrect and misleading. 2) The download page states Choose this if you are at all unsure. This is also clearly incorrect. Someone attempting to use this version must be absolutely sure what CPU they have, and possibly even the exact version. 3) The error message from the installer is unhelpful. It asks the user to please use a kernel appropriate for your CPU, yet there is no hint as to where this kernel may be found. What is the user supposed to do at this point? 4) Making this change will cause PCs which currently use Ubuntu to no longer be able to do so. 5) Making this change will limit the hardware compatibility in ways which very few users (even very technically inclined ones) would expect. The first three items are more or less administrative and documentation problems. Names, instructions, and web pages are providing wrong, misleading, or inadequate information. The latter two items are the serious problems. Dropping users and dropping support for basic hardware isn't a decision to be made lightly, and it certainly shouldn't be made quietly by a few people and sprung on everyone else by surprise as a fait acompli. It's something that should be discussed more widely with respect to what markets are being served and what the overall support strategy should be. There are basically two types of x86 Ubuntu offered at present - 32 bit and 64 bit. Most new CPUs sold today are 64 bit, so that is where the future of Ubuntu ought to be. 32 bit is for older (legacy) hardware or for specialised uses such as low power or embedded applications. In other words, 64 bit is for mainstream desktops, laptops and servers and 32 bit is for legacy and special purpose. If this is a correct way of looking at things, then it doesn't make much sense to exclude support for some 32 bit processors, nor does it make sense to come out with a special third version (x86-64, i686, i586) to handle these cases. Rather I think it would make more sense to leave CPU support in 8.10 the same as it was in 8.04 (C3 works). Time will solve this problem anyway as 32 bit simply fades away. There was a suggestion that people who are affected should simply switch to a different distro. I'm not sure that is the sort of message which Ubuntu wants to give (that users get dropped and other distros have wider hardware support). Also, what do the people at Debian think? Should both distros follow a common policy on this? On the other side of the coin, in return for these potential problems, we get the cmov instruction. However, the benefit from this instruction is apparently not that obvious. See the following discussion between Linus Torvalds and Grzegorz Kulewski. http://ondioline.org/mail/cmov-a-bad-idea-on-out-of-order-cpus;. In any event, I think this question needs more discussion (including wider participation than just this list) as it seems to have a lot of implications beyond the purely technical ones. -- Ubuntu-devel-discuss mailing list Ubuntu-devel-discuss@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-devel-discuss
