Re: [RFC/RFA] --with-build-time-tools configure option

[Gunther Nikl <gni at gecko dot de>]

On Thu, Jan 05, 2006 at 03:29:01PM +0100, Paolo Bonzini wrote:
> >I did an additional test and that one failed. Your patch does only work for
> >a normal cross-build when using --target=<target> only. Thats what I tested
> >initially. Now I tried to build with a cross-compiler by using --build and
> >--host(==--target) and I tried a canadian cross. In both cases the build
> >still uses the "wrong" tools from $prefix/bin/$target-<tool>. These should
> >use tools from $prefix/$target/bin too.
> 
> No.  You only want to use $prefix/$target/bin if the installed compiler 
> will.

  In this case the path refers to the host system and the installed compiler
  on the $host will use $prefix/$target/bin for sure. Thats what all my gcc
  installations do. However, I don't believe that this point is important.

> If you're on a --build != --host configuration, you don't know  what
> assembler/linker/nm the installed compiler will use, because it's a 
> radically different file system (a different machine).  Then, you just 
> trust that it will have the same characteristics as whatever 
> assembler/linker/nm can be found on the path.

  I am sorry to say, but I don't see the point in using tools from the
  path if I can reach them through a *frontend*. With --build != --host
  the freshly built compiler can't be used for anything, thus you need
  to use again an already installed compiler to compile for the target.
  Because of these scripts (as,collect-ld) in gcc/ the installed(!) build
  compiler (for the target) uses the *wrong* tools! I think these scripts
  in gcc/ are a major annoyance. They appear to complicate the build
  process and to break it at times.
  Why are these scripts introduced at all? Building with --build != --host
  was painless with GCC 2.95 or later. Now its broken :-/

> In general, when building --build != --host configurations, you're 
> better off building in a combined tree.

  I don't follow. I am interested in building GCC only.

  Gunther