Re: Oops with tip/x86/fpu

Dave Hansen
2015-03-05T18:34:45Z

On 03/05/2015 10:22 AM, Oleg Nesterov wrote:
> On 03/05, Oleg Nesterov wrote:
>> I _think_ that the difference is that eager_fpu_init()->xrstor_state()
>> was called before apply_alternatives(), so it used XRSTOR.
>>
>> Note also that (before this commit) restore_fpu_checking() was almost
>> never called right after init_fpu(). If use_eager_fpu() == T.
>>
>> After this commit the first xrstor_state() uses XRSTORS. And that is
>> how (I think) 'noxsaves' makes the difference.
>>
>>
>> So. I can be easily wrong, but so far I _think_ that this commit disclosed
>> another problem. And even if I am wrong and this commit is buggy, we need
>> to understand why ;)
>>
>> I'll try to think about debugging patch, I can't reproduce this problem
>> on my machine...
>
> Dave. could please run the test-case below?
>
> Without 'noxsaves', and without my commit.

So you want it tested at 4b2e762e2e5 in tip/x86/fpu?