yann@1: When configuring a s390->s390 or cris->cris crosscompiler
yann@1: (ok, I haven't hit this yet, but one of these days I'll get me an account
yann@1: on an s390, and then I'll need this patch :-), you'll get the
yann@1: following error:
yann@1: 
yann@1: + /build/s390-unknown-linux-gnu/gcc-3.3-glibc-2.3.2/gcc-3.3/configure
yann@1: --target=s390-unknown-linux-gnu --host=s390-host_unknown-linux-gnu
yann@1: --prefix=/result/s390-unknown-linux-gnu/gcc-3.3-glibc-2.3.2
yann@1: --enable-languages=c
yann@1: --with-local-prefix=/result/s390-unknown-linux-gnu/gcc-3.3-glibc-2.3.2/s390-
yann@1: unknown-linux-gnu --enable-threads=no --without-headers --with-newlib
yann@1: --disable-shared
yann@1: ...
yann@1: *** --with-headers is only supported when cross compiling
yann@1: 
yann@1: This error pops up only when you're using Daniel Jacobowitz's technique
yann@1: of slightly changing the target and host tuples to make them different
yann@1: enough to force gcc's build system to not try to pull in system libraries
yann@1: or headers.  This technique is needed e.g. to build an x86 -> x86
yann@1: cross-compiler.
yann@1: (The LFS developers ran into the same bug that prompted me to use
yann@1: this technique; they point people who run into it to
yann@1: http://linuxfromscratch.org/~greg/pure_lfs.txt, which is a different
yann@1: way of avoiding this problem.  I think the tuple tweak is the way to go, though.)
yann@1: 
yann@1: config-patches@gnu.org rejected this patch, on the grounds that there
yann@1: is only one vendor of each of those two architectures, so the 
yann@1: canonicalization is by definition correct.  When I pointed out the
yann@1: difficulty this causes for people building s390 -> s390 or
yann@1: cris -> cris compilers that are incompatible with the system
yann@1: libraries and thus must be built like cross-compilers, he grumped and said 
yann@1: "autoconf should let you specify a cross-compiler in some other way than
yann@1: comparing tuple strings".
yann@1: 
yann@1: 
yann@1: 
yann@1: --- gcc-3.3/config.sub.old	Sun Jun  8 20:38:47 2003
yann@1: +++ gcc-3.3/config.sub	Sun Jun  8 20:40:34 2003
yann@1: @@ -433,9 +433,12 @@
yann@1:  	crds | unos)
yann@1:  		basic_machine=m68k-crds
yann@1:  		;;
yann@1: -	cris | cris-* | etrax*)
yann@1: +	cris | etrax*)
yann@1:  		basic_machine=cris-axis
yann@1:  		;;
yann@1: +	cris-*)
yann@1: +		basic_machine=cris-`echo $basic_machine | sed 's/^[^-]*-//'`
yann@1: +		;;
yann@1:  	da30 | da30-*)
yann@1:  		basic_machine=m68k-da30
yann@1:  		;;
yann@1: @@ -820,11 +823,17 @@
yann@1:  	rtpc | rtpc-*)
yann@1:  		basic_machine=romp-ibm
yann@1:  		;;
yann@1: -	s390 | s390-*)
yann@1: +	s390)
yann@1:  		basic_machine=s390-ibm
yann@1:  		;;
yann@1: -	s390x | s390x-*)
yann@1: +	s390-*)
yann@1: +		basic_machine=s390-`echo $basic_machine | sed 's/^[^-]*-//'`
yann@1: +		;;
yann@1: +	s390x)
yann@1:  		basic_machine=s390x-ibm
yann@1: +		;;
yann@1: +	s390x-*)
yann@1: +		basic_machine=s390x-`echo $basic_machine | sed 's/^[^-]*-//'`
yann@1:  		;;
yann@1:  	sa29200)
yann@1:  		basic_machine=a29k-amd