> > What target did you configure GDB for? What does GDB print out when
> > you start it up with the -nw flag?
>
> gdb 4.18, configured for i686-pc-linux-gnu
I don't think the SSE support was included in GDB 4.18. However, the
disassembler is a semi-independent library, and may have had those
instructions added to its tables before GDB learned to handle the SSE
registers.
You can get a newer GDB snapshot from http://sourceware.cygnus.com/gdb.
Note that you need to patch your kernel before you can debug SSE
programs. See http://sourceware.cygnus.com/gdb/papers/linux/linux-sse.html.
