On 20 Nov 2014 10:36, Roland McGrath wrote:
> > some (many?) targets require some C library headers before they can build
> > for the target at all.
> 
> Not to build the compiler itself or other host tools, only to build the
> target libraries.
> 
> > how exactly are you building the first GCC w/out any C library headers ?
> 
> Just 'make all-gcc'.  It's only things in the 'all-target-*' makefile
> targets that need target C library headers.
> 
> In the beforetime, the long long ago, the build of libgcc was intertwined
> directly with the compiler build.  But for several versions now (all that
> we support for building libc, I'm pretty sure), it's just a normal target
> library like all the others (libstdc++ et al) in the build system.

it is still integrated ... at least, we attempted exactly that in CrOS with 
gcc-4.8 and it was not possible to build libgcc & libstdc++ w/out also building 
the local copy of the compiler.

i'm not sure why we're forcing this from the perspective of glibc.  being able 
to install the C library headers for a target should not require probing the 
assembler/linker/compiler.  the installed headers are the same regardless.
-mike