Re: [PATCH v3] elf: Add tst-ldconfig-bad-aux-cache test [BZ #18093]

[Joseph Myers <joseph at codesourcery dot com>]

On Mon, 13 May 2019, Carlos O'Donell wrote:

> > There are lots of other places with such hardcoded paths.  See e.g. bug 
> > 20138 asking for --sysconfdir to be respected.  Note that some such paths 
> > are in installed headers, including paths.h; should those paths in 
> > installed headers also depend on configure options?
>  
> Would the _nl_default_dirname discussion set some precedent for this?
> 
> https://sourceware.org/bugzilla/show_bug.cgi?id=14664
> https://sourceware.org/ml/libc-alpha/2012-12/msg00192.html

It's certainly relevant.

> Namely that paths.h is not a part of the ABI, and therefore configure
> options can and should change the values in the header to match.

There's a general question here of when installed headers should depend on 
configure options - because when they do, that sets bounds on what 
multilib configurations can share a single set of installed headers.  We 
expect multilib configurations for e.g. -m32 and -m64 to be able to share 
headers.  Changing paths.h would imply that glibc builds with different 
paths can't share installed headers.  (An edge case for the question of 
whether headers can be shared would be e.g. powerpc64 BE and LE - right 
now I think they can as there are no LE-specific headers, and GCC does 
have some multilib configurations with both BE and LE multilibs, but those 
configurations use their own lib* directory names nothing else in the 
toolchain knows about, so might not work well for other reasons.)

-- 
Joseph S. Myers
joseph@codesourcery.com