Re: [RFC,PATCH] Extend MULTILIB_EXCEPTIONS with a check for absent options

["Joseph S. Myers" <joseph at codesourcery dot com>]

On Fri, 13 Jun 2008, Andreas Krebbel wrote:

> provide a solution I would like to split the MULTILIB_OSDIRNAMES
> variable into two.  One for the location where to look for the
> multilibbed OS libs and one for the install location of libgcc_s.so.
> Does this make sense?

I have a different use for a split of MULTILIB_OSDIRNAMES.  Suppose you 
have a toolchain with multiple sysroots (using SYSROOT_SUFFIX_SPEC, 
possibly as generated by one of the print-sysroot-suffix.sh scripts), and 
those sysroots in turn each contain both 32-bit and 64-bit libraries.  
Then when MULTILIB_OSDIRNAMES is used for searching inside a sysroot you 
always want values such as plain "." or "../lib64" (so more than one 
multilib ends up with the same value), but when used for the libgcc_s 
install path (and other libraries installed by GCC) you need every 
multilib to have its own path, e.g. "../lib64" and 
"../lib64/sysroot-name".  Right now, implementing this requires using 
STARTFILE_PREFIX_SPEC in the way it was used to implement lib64 
directories before MULTILIB_OSDIRNAMES was implemented.  For an example of 
such a configuration submitted for FSF GCC, see 
<http://gcc.gnu.org/ml/gcc-patches/2008-05/msg01397.html>.  The 
MULTILIB_OSDIRNAMES and STARTFILE_PREFIX_SPEC settings there do work - but 
it would be good to have a cleaner way of implementing this.

-- 
Joseph S. Myers
joseph@codesourcery.com