Ralf Baechle wrote:
On Thu, Oct 06, 2005 at 02:52:22PM -0400, Greg Weeks wrote:
I'd remembered some problems ages ago, but had thought they'd been
fixed. John was just picking my brain about it so I thought I'd ask to
The problems I recall were all related to being preempted just while
fiddling with the hardware FPU - can't happen on the fpu-less 4Kc.
Another issue fixesd recently even though more cosmetic were a bunch
of global variables.
The code base I'm dealing with is a 2.6.13 derivative
with PREEMPT_RT support. Looks like the problem was
due to PREEMPT_RT confusing fpu_emulator_cop1Handler()
resulting in a SIGBUS nailing the associated task.
I have it sort of working for soft FPU but expect it
requires some attention to safely access a HW FPU where
emulation assistance is needed.