spca5xx freezes system

[D. Hugh Redelmeier]

| I emailed the developer again yesterday, and he told me that he
| believes the problem to be gcc-4.1 in FC5 (and not its kernel).  That
| at least makes more sense than blaming the kernel, when the problem
| also existed with an official kernel.org kernel too.

Interesting.  If this is correct, it still probably indicates a bug in
the driver code rather than GCC.  Usually what has happened is that
the C compiler has gotten better at optimization, exposing new places
where the driver needed to use "volatile" or some similar mechanism.

Not always: there was a horrible bug in FC4's X last summer that was
caused by a subtle GCC bug in handling casts to volatile qualified
types.  It took several of us to convince the GCC folk
that they were reading the C standard unreasonably.  See the thread
starting here: http://gcc.gnu.org/ml/gcc/2005-07/msg00664.html

Here's how to test the hypothesis: recompile the driver with no
optimization.  This may seem to require spelunking makefiles that are
very convoluted and obscure.  If so, there is a cheating shortcut that
might work:  capture the makefile log, manually edit out the
optimization flags, and manually rerun the commands.

If the driver works when compiled without optimization, this is a
strong indication that the driver is not getting along with GCC
changes.  This is a good start to diagnosing the problem.  If the
driver does not work when compiled without optimization, it is very
probably not a compiler/code mismatch.

I admire the effort to which you (plural) have gone to chase this down.  
Many would just wait until someone else diagnosed it.