cross-compilation documentation

[Dan Kegel]

Zack Weinberg wrote:
> Andrew Pinski <pinskia@physics.uc.edu> writes:
>>RCS file: /cvs/gcc/gcc/gcc/config/rs6000/linux.h,v
>> 
>>-#ifdef IN_LIBGCC2
>>+#if defined (IN_LIBGCC2) && !defined (inhibit_libc)
>> #include <signal.h>
>> ...
> 
> For what it's worth, that looks like the right fix to this immediate
> problem.  We want to decouple libgcc build from compiler build for
> other reasons, but that's sufficiently invasive that it's probably a
> 3.5 item at this point (the way I wanna do it, it needs bootstrap to
> run at top level, and it involves moving a lot of files).

If this is the right way to go, then you need to patch
not just rs6000, but also just about every other architecture,
don't you?
I did verify just now that --without-headers fails with gcc-3.3
when building for alpha, for instance.  The error message is

In file included from tconfig.h:18,
                  from /build/alpha-unknown-linux-gnu/gcc-3.3-glibc-2.3.2/gcc-3.3/gcc/libgcc2.c:36:
/build/alpha-unknown-linux-gnu/gcc-3.3-glibc-2.3.2/gcc-3.3/gcc/config/alpha/linux.h:68:20: signal.h: No such file or directory
/build/alpha-unknown-linux-gnu/gcc-3.3-glibc-2.3.2/gcc-3.3/gcc/config/alpha/linux.h:69:26: sys/ucontext.h: No such file or directory
make[2]: *** [libgcc/./_muldi3.o] Error 1
make[2]: Leaving directory `/home3/dank/crosstool-0.7/build/alpha-unknown-linux-gnu/gcc-3.3-glibc-2.3.2/build-gcc-core/gcc'

I'm going to keep on installing bootstrap glibc headers
for now, even though it's arcane and undocumented.

BTW, there is a PR for --without-headers not working; see
http://gcc.gnu.org/PR8180
IMHO this is a regression from gcc-3.2.3, and deserves
at least a documented workaround for the very next release,
even if we can't do a real fix until 3.5.
- Dan

-- 
Dan Kegel
http://www.kegel.com
http://counter.li.org/cgi-bin/runscript/display-person.cgi?user=78045