[llvm-dev] Minimal glibc version supported by LLVM build

[Daniel Neilson via llvm-dev]

Correction to Philip’s statement, below, about the glibc version packaged with Centos 6.4 — it includes glibc v2.12. LLVM will build on this system just fine.

-Daniel

On Oct 4, 2017, at 1:17 PM, Philip Reames via llvm-dev <llvm-dev at lists.llvm.org<mailto:llvm-dev at lists.llvm.org>> wrote:


+ Rui, the patch author

Do we know what the oldest glibc which works with this patch is?

For context, the most recent REHL 5 ships with glibc 2.5.  REHL 6 ships with 2.12 and REHL ships with 2.17.  I have evidence that this breaks at least on Centos 6.4 which is derived from REHL 6.

This appears to break on anything REHL 6 (or earlier) derived.  I think this patch needs to be reverted.  Thoughts?

Philip

On 10/04/2017 12:08 AM, Serguei Katkov via llvm-dev wrote:
Hi All,

The landed patch https://reviews.llvm.org/D38481 introduced the usage of CPU_COUNT defined in glibc sched.h header.
I failed to find this symbol in sched.h of glibc version 2.5-24, so compilation just fails.
/home/dolphin/merge-from-upstream-area/ws/pristine/lib/Support/Threading.cpp: In function ‘unsigned int llvm::hardware_concurrency()’:
/home/dolphin/merge-from-upstream-area/ws/pristine/lib/Support/Threading.cpp:80:26: error: ‘CPU_COUNT’ was not declared in this scope
     return CPU_COUNT(&Set);
                          ^

It is buildable with newest version of glibc.
I tried to find a requirements for glibc version in LLVM documentation but failed.
So I wonder whether there is such requirement or not.
Could anyone point me to this documentation?

I'm trying to understand whether patch is wrong which relies on availability of library but does not check the symbol itself or this version of glibc is not supported.

Thank you,
Serguei.




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