Re: [PATCH 20/39] NLKD/x86-64 - switch_to() floating pointadjustment

From: Jan Beulich
Date: Thu Nov 10 2005 - 09:06:58 EST


>>> Andi Kleen <ak@xxxxxxx> 10.11.05 14:24:53 >>>
>On Wednesday 09 November 2005 15:15, Jan Beulich wrote:
>> Touching of the floating point state in a kernel debugger must be
>> NMI-safe, specifically math_state_restore() must be able to deal with
>> being called out of an NMI context. In order to do that reliably, the
>> context switch code must take care to not leave a window open where
>> the current task's TS_USEDFPU flag and CR0.TS could get out of sync.
>
>Didn't we agree earlier on moving unlazy_fpu() down instead?

I wasn't sure about that, and hence I submitted it the way I had coded it.

Jan

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