On 2020-05-16 06:03 +0300, Firas Khalil Khana via lfs-dev wrote: > On Sat, May 16, 2020 at 5:48 AM Xi Ruoyao via lfs-dev > <lfs-dev@lists.linuxfromscratch.org> wrote: > > On 2020-05-16 04:37 +0300, Firas Khalil Khana via lfs-dev wrote: > > > On Sat, May 16, 2020 at 4:19 AM Xi Ruoyao via lfs-dev > > > <lfs-dev@lists.linuxfromscratch.org> wrote: > > > > On 2020-05-15 19:28 +0300, Firas Khalil Khana via lfs-dev wrote: > > > > > On Fri, May 15, 2020 at 6:48 PM Pierre Labastie via lfs-dev > > > > > <lfs-dev@lists.linuxfromscratch.org> wrote: > > > > > > On Fri, 2020-05-15 at 18:21 +0300, Firas Khalil Khana via lfs-dev > > > > > > wrote: > > > > > > > Hey there, > > > > > > > > > > > > > > I'd like to inquire about the actual need for the /toolchain > > > > > > > symlink > > > > > > > on the host system. > > > > > > > > > > > > > > Apparently, failure to create this link causes > > > > > > > configure/build/linking > > > > > > > problems starting from Chapter's 5 libstdc++ with errors in the > > > > > > > form > > > > > > > of failure to perform sanity checks (mostly because cpp's (gcc -E) > > > > > > > include paths are wrong), ld not finding crt1.o, crti.o, and so > > > > > > > on... > > > > > > > > > > > > > > I'm not really sure why this link is required though. I understand > > > > > > > that it's currently a must to build LFS (apparently not much > > > > > > > explanation is provided to how GCC/Binutils searching/configuring > > > > > > > works with regards to directory layout,so we need to cover for > > > > > > > $LFS/tools and /tools with the latter being silently used in some > > > > > > > places to make the toolchain build; by silently I mean > > > > > > > automatically > > > > > > > appended to $LFS without knowing when/where so it won't error > > > > > > > out), > > > > > > > but wouldn't specifying correct flags when configuring GCC, > > > > > > > binutils > > > > > > > and Glibc remove the need for such symlink? > > > > > > > > No, unless we use some DESTDIR installation. It's Pierre's cross > > > > Chapter 5 > > > > experiment: > > > > > > > > http://www.linuxfromscratch.org/~pierre/lfs-modified/ > > > > > > > > > > I've checked piere's modifications, and they're most welcome, but I'm > > > only talking about removing the `/tools` symlink without touching > > > anything else. > > > > > > I don't think GCC needs its source modifications be changed (meaning > > > that we'll still use the regular `/tools/lib`), and I think that's > > > made possible because sysroot is actually appended before ld's search > > > path (one thing that might require minor modification is that when ld > > > inside /tools/$LFS_TGT/bin tries to get the `../lib` (after modifying > > > `t-linux64` to use `../lib` instead of `../lib64`) path relative to > > > where it is, it won't get the right `lib` folder as it gets to > > > `/tools/$LFS_TGT/lib` when it should've been `/tools/lib` based on the > > > configuration passed to the toolchain components. > > > > It's not about library search path. It's about GCC internal executable > > path. > > When you configure GCC with --prefix=/mnt/lfs/tools, the path > > "/mnt/lfs/tools/libexec/gcc/x86_64-pc-linux-gnu/10.1.0/" gets hardcoded into > > executables gcc, g++, etc. When this GCC build is used, it searches > > internal > > executables cc1, cc1plus, etc. in this path. So if we use -- > > prefix=/mnt/lfs/tools for GCC pass 2, it will be unusable at all in chroot > > (gcc > > will say something like 'cc1 not found'). And there is a GCC library path > > "/mnt/lfs/tools/lib/gcc/x86_64-linux-gnu/10.1.0" contains libgcc libraries > > and > > headers. It's also hardcoded. > > > > ^ This needs to be added to the book, along with explanations for the > rest of the stuff LFS does to get a cross/native toolchain to work. > Also if that's the case, why not rely on empty prefixes, and resolve > to `DESTDIR`s instead?
If we use --prefix=/usr and DESTDIR=/mnt/lfs for GCC pass 2, it would be only usable in chroot, and unusable outside chroot. So the remaining packages in Chapter 5 need to be built either by GCC pass 1, or inside the chroot environment. That's exactly Pierre's modification. /* snip */ > > > https://stackoverflow.com/questions/59705962/ld-fails-to-find-libc-when-compiling-first-pass-of-cross-gcc > > > > The mistake is using gcc-9.x instruction for gcc-8.x. gcc-8.x needs " > > --disable- > > libmpx". > > > > I was just referring to a similar problem, `libmpx` and `libmudflap` > are long gone in GCC... > > > Please do not arbitrarily change package version. And, please investiate the > > error message to understand what's happening when you hit a problem, instead > > of > > guessing and blaming "/tools". > > > > I'm not "arbirarily" changing the package version, and I'm > investigating (and documenting) everything I'm encountering. I decided > to tackle this `/tools` symlink and I'm trying to wrap my head around > its actual need at this point with the little documentation available > about how binary/include/lib paths work in a toolchain. > > > "/achm" is as good (or "bad") as "/tools". Just some non-FHS directories > > nobody > > uses. If you want to be "good" (FHS-compliant) use something like > > "/var/lib/lfs/tools", or "/opt/lfs/tools". > > > > > If it were simple, can you please provide instructions on how to "not > > > create" this symlink for users who don't want to pollute their host > > > system? > > > > Nobody except LFS uses /tools. So it's not a polluation. > > > > I'm not saying that other projects are using `/tools` (many LFS > derived projects do though...), what I meant by polluting is creating > an additional symlink in the root directory of your host system... If you really hate /tools, use /opt/lfs/tools or something. -- Xi Ruoyao <xry...@mengyan1223.wang> School of Aerospace Science and Technology, Xidian University -- http://lists.linuxfromscratch.org/listinfo/lfs-dev FAQ: http://www.linuxfromscratch.org/faq/ Unsubscribe: See the above information page
