Comment 5 for bug 738098

How are you building gcc? It sounds like you're trying to build a gcc from upstream sources, not from one of the Ubuntu packages, correct?

The default binutils path does not include the multiarch directories because this change was rejected by binutils upstream and the Debian maintainer when it was first proposed - we were told that this should be put only in the gcc spec files, which is how it's implemented now in natty. If you are bootstrapping a gcc build other than the Ubuntu package, you will have to apply the same Ubuntu patches for multiarch support to your gcc as well if you expect it to be used with the system libc.