PATCH: BZ #14664: changing prefix breaks "make check-abi-libc"

[David Miller]

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.