Re: Possible issue with hurd: Fix abi-tag, following ba90e05

[Joseph Myers <joseph at codesourcery dot com>]

On Mon, 9 Feb 2015, Samuel Thibault wrote:

> Hello,
> 
> Adhemerval Zanella, le Mon 09 Feb 2015 16:05:42 -0200, a écrit :
> > Since ae20c9a17cd95b6f367209c2a9075587616ceb42 my powerpc builds can not load
> > older binaries using the new loader,
> 
> Ergl.
> 
> So I guess it's actually ba90e05052ce57db51e3cb18978614fd0db5c7ef which
> was overly optimistic about possibly removing the gnu -> gnu-gnu
> transformation.  Joseph, do you know the details?

Maybe - the comment referred to shlib-versions, and the libc-abis uses 
were unaffected, but actually this transformation was significant for 
host_os / config-os uses in abi-tags as well.

I think the right fix would be to move abi-tags away from a shared file - 
instead of taking the first matching entry from a shared file, take the 
unique matching entry from the first abi-tags file found in sysdeps 
directories (so you'd have sysdeps/unix/sysv/linux/abi-tags and 
sysdeps/mach/hurd/abi-tags, missing the present first column, and the 
toplevel file might just have comments documenting the format and the 
allocated OS numbers but not being used to determine which applies to the 
current glibc build).

But if the comment about "earlier entries taking precedence over later 
entries" is accurate, .*-.*-gnu.* should have no effects on any system for 
which .*-.*-linux.* matches.

(Of course, a simpler fix might be to restore the host_os transformation 
but with a more accurate comment.)

-- 
Joseph S. Myers
joseph@codesourcery.com