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Re: [PATCH] Update powerpc ABI data
On Tue, 1 May 2012, Roland McGrath wrote:
> > Most of them were also wrong on x86 and sparc, but David only updated
> > the abi lists that he could test, I suppose. Most of the missing
> > symbols are related to the long double switch. The abi files of the
> > other architectures will need similar updating.
>
> The files certainly were right at one time (like when I wrote all this
> stuff to begin with), and certainly changes like the long double switch
> should only have affected newer symbol versions, not preexisting ones at
> the time. I wonder if there was some bug in the merge/extract scripts
> so the data David extracted isn't what was actually in use originally.
The extraction was (I presume) using exactly the same script that was used
before by make check-abi to extract the data to compare against the lists
of symbols from the newly built libraries. Before
commit 00bbd29b35717f0de8b97e5b1e6fd3e979808ec3
Author: Ulrich Drepper <drepper@gmail.com>
Date: Sat Jan 7 19:23:45 2012 -0500
Update ABI information
the data hadn't been updated (other than adding one empty file) since
April 2003 (between 2.3.2 and 2.3.3). So only changes to 2.3.2 or older
symbol versions would necessarily indicate problems (as opposed to the
January update not being based on real data for most architectures).
I do think it's useful to compare the ABI baselines for architectures you
maintain against old binaries of various past glibc versions, to see if
the current baselines have differences in old symbol versions to what's in
the old binaries - I've done that for ARM and MIPS (details of the results
on libc-ports). Even where the binaries are from distributors with local
patches applied that might include backports of new symbols and symbol
versions, such comparisons are still a useful starting point for looking
for ABI breakages that crept in while check-abi wasn't maintained or run
by default.
--
Joseph S. Myers
joseph@codesourcery.com