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Re: PATCH: BZ #14664: changing prefix breaks "make check-abi-libc"
From: Siddhesh Poyarekar <siddhesh@redhat.com>
Date: Mon, 10 Dec 2012 10:35:27 +0530
>> Could you please explain how this is different than just deleting the symbol?
>>
>> Your changes make the test for this particular symbol a tautology.
>>
>> You check to see that the size is the size you set which is always true.
>>
>> The check you want is to see if the size you set matches the expected ABI size.
>>
>
> In case of a prefix + a constant in a data symbol, the latter should
> be unchanging from the viewpoint of glibc, while the former is the
> responsibility of the distribution. IMO, trying to check if some
> prefix is a pre-computed value is not a sensible ABI check from the
> glibc point of view.
I completely disagree.
Every distribution sets the prefix to /usr
Therefore, every binary compiled against those GLIBC's has
that symbol's fixed size in any R_*_COPY relocations referencing
those symbols.
Therefore, changing the size of the symbol will make the dynamic
linker ERROR and the application will fail, since the dynamic linker
checks the R_*_COPY relocations size against the one in symbol itself.
It is part of the ABI, whether you like it or not.
Removing this check is wrong.