PREEMPT
Does anyone know of any current problems with CONFIG_PREEMPT on a 4kc malta board? We're seeing some oddness in the floating point emulator with PREEMPT_RT and wondered if it was in our RT code, or if it's from the base kernel code.
Greg W
Quoted 4 lines · Greg Weeks
Does anyone know of any current problems with
CONFIG_PREEMPTon a 4kc malta board? We're seeing some oddness in the floating point emulator withPREEMPT_RTand wondered if it was in our RT code, or if it's from the base kernel code.
No known problem in current problems in that area.
Ralf
Quoted 4 lines · Ralf Baechle
On Thu, Oct 06, 2005 at 02:36:25PM -0400, Greg Weeks wrote:
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Does anyone know of any current problems with
CONFIG_PREEMPTon a 4kc malta board? We're seeing some oddness in the floating point emulator withPREEMPT_RTand wondered if it was in our RT code, or if it's from the base kernel code.No known problem in current problems in that area.
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 be sure.
Greg W
Quoted 3 lines · Greg Weeks
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 be sure.
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.
Ralf
Quoted 10 lines · Ralf Baechle
Quoted 1 line · Greg Weeks
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 be sure.
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.
-john
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[email protected]
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The code base I'm dealing with is a 2.6.13 derivative with
PREEMPT_RTsupport. Looks like the problem was due toPREEMPT_RTconfusingfpu_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.
Um, did no one have a look at Atsushi Nemoto's patch earlier today that addressed pre-emption and CPU1, or am I missing something?
-Steve
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Quoted 1 line · On Thu, 6 Oct 2005 13:45:55 -0500 (CDT), [email protected] said:
sjhill> Um, did no one have a look at Atsushi Nemoto's patch earlier sjhill> today that addressed pre-emption and CPU1, or am I missing sjhill> something?
The patch I posted yesterday affects just for ptrace. I suppose this is not irrelevant.
Also, though it might irrelevant too, I think there are still possible bug related signal and fpu_context. I'll post a patch again.
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Atsushi Nemoto