Code change:
COPY host-x86_64/dist-x86_64-linux/build-binutils.sh /tmp/ RUN ./build-binutils.sh <del> # libssh2 (a dependency of Cargo) requires cmake 2.8.11 or higher but CentOS # only has 2.6.4, so build our own COPY host-x86_64/dist-x86_64-linux/build-cmake.sh /tmp/ RUN ./build-cmake.sh # Build a version of gcc capable of building LLVM 6 </del> <ins> # Need at least GCC 5.1 to compile LLVM nowadays </ins> COPY host-x86_64/dist-x86_64-linux/build-gcc.sh /tmp/ <del> RUN ./build-gcc.sh </del> <ins> RUN ./build-gcc.sh && apt-get remove -y gcc g++ </ins> <del> # CentOS 5.5 has Python 2.4 by default, but LLVM needs 2.7+ </del> <ins> # Debian 6 has Python 2.6 by default, but LLVM needs 2.7+ </ins> COPY host-x86_64/dist-x86_64-linux/build-python.sh /tmp/ RUN ./build-python.sh <del> # Now build LLVM+Clang 7, afterwards configuring further compilations to use the </del> <ins> # LLVM needs cmake 3.4.3 or higher, and is planning to raise to 3.13.4. COPY host-x86_64/dist-x86_64-linux/build-cmake.sh /tmp/ RUN ./build-cmake.sh # Now build LLVM+Clang, afterwards configuring further compilations to use the </ins> # clang/clang++ compilers. <del> COPY host-x86_64/dist-x86_64-linux/build-clang.sh host-x86_64/dist-x86_64-linux/llvm-project-centos.patch /tmp/ </del> <ins> COPY host-x86_64/dist-x86_64-linux/build-clang.sh /tmp/ </ins> RUN ./build-clang.sh ENV CC=clang CXX=clang++ <del> # Apparently CentOS 5.5 desn't have `git` in yum, but we're gonna need it for # cloning, so download and build it here. COPY host-x86_64/dist-x86_64-linux/build-git.sh /tmp/ RUN ./build-git.sh # for sanitizers, we need kernel headers files newer than the ones CentOS ships # with so we install newer ones here COPY host-x86_64/dist-x86_64-linux/build-headers.sh /tmp/ RUN ./build-headers.sh # OpenSSL requires a more recent version of perl # with so we install newer ones here COPY host-x86_64/dist-x86_64-linux/build-perl.sh /tmp/ RUN ./build-perl.sh </del> COPY scripts/sccache.sh /scripts/ RUN sh /scripts/sccache.sh

Related discussion:
text: The alternative to this would be Support RHEL N until it is retired I think we should not officially support retired OS versions (well, maybe with some grace period), so I prefer this option. Supporting 14 year old kernels seems a bit too much to me. each RHEL N is bootstrapped on RHEL N-1 and often kept that way -- meaning a lot of our RHEL 6 builders are still running on a RHEL 5 kernel Is it possible to apply kernel patches to those builders to add support for functionality like CLOEXEC? Or build Firefox separately on RHEL 6?
I think it won't be fruitful for us to debate the merits of stable enterprise kernels, but no, this is not a possibility. An alternative take is "Red Hat should be responsible for the work in Rust to maintain the support they want" -- here I am, ready and willing. I definitely can't change those kernels. The ones that are stuck on N-1 are precisely to avoid rocking the boat, and backporting features is a big change. Some of our arches do eventually update the builders to their matching N kernel, but some don't, and I don't know all the reasons. If the workarounds are removed, then I will have to reapply them in our own builds. This assumes I keep using only our own binaries -- if I ever have to re-bootstrap from upstream binaries for stage0, I would also have to use some interception (like ) to hack in the workarounds. This is all possible, but much worse than the status quo of maintaining support here.
I think this sounds reasonable. We aren't going to be able to update these kernels, it's just a question of when we would drop support for these OSes. Especially given that we wont need RHEL 5 CI support, I think that leaving things as they are is fine. I opened this issue to verify two things: 1) That we weren't intending on supporting RHEL 5 "forever", and had a clear date when to drop support. 2) That someone from Red Hat actively cared about supporting these older kernels. It looks like both these things are true. We should remove RHEL 5 workarounds after November 30, 2020. This issue can be postponed until then.