Bootstrapping new architectures with C++

[Sam Thursfield <sam dot thursfield at codethink dot co dot uk>]

Hi!

Could someone explain how GCC can be cross-built for new architectures 
now that it requires C++ to build? It seems to be that there is the 
following dependency loop:

  - Building libstdc++ for target requires a libc for the target
  - Building libc for target requires a gcc for target
  - Building gcc for target requires at least a g++ that cross-compiles
  - The cross-g++ for the target requires a libstdc++ built for the target

For architectures that GCC is already built for, I hear that this will 
be solved by ensuring GCC version N can be built by version N-1. But how 
will this work for a new architecture, which doesn't yet have a GCC 
built for it?

I apologise if this has been covered before, but I didn't find anything 
searching back through the list.

Thanks
Sam