Bug#1050992: hwcap default search paths changed
Hi,
On 2023-09-01 09:14, Mathieu Malaterre wrote:
> Source: glibc
> Version: 2.37-1
>
> Previously defined hwcap search paths have been changed. Those
> specified in `man 8 ld.so` are no longer accurate (bug #1050930).
[snip]
Yes, the old AT_HWCAP mechanism has been deprecated in glibc 2.33 in
favor of the glibc-hwcaps mechanism, and removed in glibc 2.37. Instead
of relying on a huge number of CPU feature combinations, the new
mechanism is based on architecture baseline level. For instance for
amd64 we have x86-64-v1 to x86-64-v4 levels defined directly in the ELF
x86-64-ABI psABI [1]. The supported directories can be queried by
running ld.so --help
That indeed means that the ld.so manpage need to be updated, thanks for
filling the bug against manpages-dev.
> Typical output on sid/i386:
> [...]
> Shared library search path:
> (libraries located via /etc/ld.so.cache)
> /lib/i386-linux-gnu (system search path)
> /usr/lib/i386-linux-gnu (system search path)
> /lib (system search path)
> /usr/lib (system search path)
>
> No subdirectories of glibc-hwcaps directories are searched.
> [...]
Indeed no level has been yet defined for i386 and I am afraid nobody is
really interested in doing so.
> If I understand correctly, this render the following .so file obsolete (unused):
>
> % file /usr/lib/i386-linux-gnu/i686/sse2/libx264.so.164
> /usr/lib/i386-linux-gnu/i686/sse2/libx264.so.164: ELF 32-bit LSB
> shared object, Intel 80386, version 1 (SYSV), dynamically linked,
> BuildID[sha1]=e66974d10aef77af7ed504266cde974d103484d6, stripped
>
> Possibly other packages might be impacted.
>
> I suspect the best upgrade path is simply to document the old hwcap
> search path have been removed, and Debian package(s) should not rely
> on them anymore (lintian warning?).
This is already documented in the upstream NEWS.gz, but it might warrant
an additional entry in NEWS.Debian.gz. The lintian warning might be a
good idea depending how widely this is used in the archive. I'll
investigate and report back.
Regards
Aurelien
[1] https://gitlab.com/x86-psABIs/x86-64-ABI
--
Aurelien Jarno GPG: 4096R/1DDD8C9B
aurelien@aurel32.net http://aurel32.net
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