Re: [BUG] GPF on hardware breakpoints (preempt_notifier)

[Anthony Liguori <anthony-rdkfGonbjUSkNkDKm+mE6A@public.gmane.org>]

Luca wrote:
> On 9/9/07, Anthony Liguori <anthony-rdkfGonbjUSkNkDKm+mE6A@public.gmane.org> wrote:
>   
>> Luca wrote:
>>     
>>> On 9/9/07, Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org> wrote:
>>>
>>>       
>>>> Luca Tettamanti wrote:
>>>>
>>>>         
>>>>> Hi,
>>>>> while debugging a program with GDB I got a GPF which seems related to
>>>>> KVM. Note that I was *not* using the debugger inside the guest nor on
>>>>> the virtual machine. The target was an unrelated userspace program.
>>>>>
>>>>>
>>>>>           
>>>> Yes, kvm is dirtily misappropriating the debug registers on older
>>>> kernels.
>>>>
>>>>         
>>> I'm runninng the current Linus' git tree, shall I test kvm.git?
>>>
>>>       
>> Do you have CONFIG_PREEMPT_NOTIFIERS enabled?
>>     
>
> No, it's disabled.
>   

If you enable it, you probably won't see this problem.  KVM emulates 
PREEMPT_NOTIFIERS using debug registers.

Regards,

Anthony Liguori

> Luca
>
>   


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