From: john cooper <john.cooper@timesys.com>
To: Ralf Baechle <ralf@linux-mips.org>
Cc: Greg Weeks <greg.weeks@timesys.com>,
linux-mips@linux-mips.org, john cooper <john.cooper@timesys.com>
Subject: Re: PREEMPT
Date: Thu, 06 Oct 2005 15:05:07 -0400 [thread overview]
Message-ID: <43457563.60505@timesys.com> (raw)
In-Reply-To: <20051006185504.GD15275@linux-mips.org>
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
>>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
--
john.cooper@timesys.com
next prev parent reply other threads:[~2005-10-06 19:11 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-10-06 18:36 PREEMPT Greg Weeks
2005-10-06 18:46 ` PREEMPT Ralf Baechle
2005-10-06 18:52 ` PREEMPT Greg Weeks
2005-10-06 18:55 ` PREEMPT Ralf Baechle
2005-10-06 19:05 ` john cooper [this message]
2005-10-06 18:45 ` PREEMPT sjhill
2005-10-07 13:55 ` PREEMPT Atsushi Nemoto
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