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

[Philip Reames via llvm-dev]

+ Rafael, the actual patch author.  Don't know how I misread that, sorry.


On 10/04/2017 11:17 AM, Philip Reames 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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>

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