Re: kernel-2.2.1-undefined references.

[Joe Buck <jbuck at Synopsys dot COM>]

> Be aware that __builtin_return_address probably will stop working
> someday in gcc.  Read my latest tirade to get an idea of why that is.

Craig, gcc is the GNU project's compiler.  That means that one of its
important roles is to be able to compile kernels (Linux or the Hurd).
Since you're the Fortran guy, you are somewhat insulated from these
issues (Fortran just doesn't make provisions for writing "close to the
machine" code).

The result is that gcc is going to have to continue to support certain
extensions for the indefinite future (though kernel developers should
not assume that "it worked in version x.y.z" is a commitment for the
future, we will need to supply some mechanisms in some cases.

It may actually be easier to support features like this if they are
specified at a higher level of abstraction.  That is, understand why Linus
is using some trick to do something, and then recommend alternative ways
to do them that are actually supportable.  e.g. if the real job is to get
a stack trace, maybe there could be some facility to provide for that
directly, possibly borrowing some code from gdb.

Despite Linus's tendency to be insulting, he is one our most important
"customers" (or, more accurately, the people who depend on the Linux
kernel working are).  We need to have sufficient facilities so that C plus
inline assembly can do the whole job.