On Sat, Jun 16, 2001 at 12:41:02PM -0700, Daniel Jacobowitz wrote:
> The biggest one was the fact that passing arguments to the inferior in
> floating point registers just didn't work. I tracked this down to at least
> three separate problems:
> - We would set last_task_used_math without clearing the ST0_CU1 bit in
> the previous task owning the FPU. When that previous task swapped
> in again, it would use the existing FP registers, and lazy_fpu_switch
> would never be called. This happened in signal.c and in ptrace.c.
First signal.c segment - calling restore_fp_context should result in a
proper FPU context switch.
> - ptrace didn't look for the FP registers in the right places. This's
> been broken since the FPU emulator merge a while back.
> - We would create new processes with the ST0_CU1 bit already set if
> their parent process had it set.
No, copy_thread clears CU1.
(Have to breed about this patch a bit more, stuff for the plane ...)
> Of course, the lazy switching isn't quite as useful as it could be, since
> every program will eventually use the FPU if not build -msoft-float - I
> think it's happening in glibc. But we can possibly work around that later.
> It still does save a great number of switches, so it's worthwhile - when it
Newer libcs shouldn't try to initialize $fcr31 to zero because that's
already the default.
> Other patches in my directory that I'm submitting along with that one:
> - kgdb-crash-resistant.diff
> - mips-gdb-with-kgdb.diff
> - mips-rtsignal.diff
These three look good, applied.