Re: seabios 0.6.1 regression

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 16.11.2010, at 11:47, Avi Kivity wrote:

> On 11/15/2010 06:09 PM, Avi Kivity wrote:
>> On 11/15/2010 05:49 PM, Avi Kivity wrote:
>>> On 11/15/2010 05:41 PM, Avi Kivity wrote:
>>>> 
>>>> I think it's a miscompile.
>>>> 
>>>> out/code16.o:
>>>> 1a4:   3e                      ds
>>>> 1a5:   6c                      insb   (%dx),%es:(%edi)
>>>> 
>>>> Note no 66 prefix.
>>>> 
>>> 
>>> It isn't, that was random crap.  All the insb() code is 32-bit.
>>> 
>> 
>> Rewriting it to use inb / stos works (jecxz ; insb; loop doesn't) so it looks like a kernel bug in insb emulation.
>> 
> 
> Turns out is was a subtle bug in the tpr optimization we do for Windows XP.  The problem happens when we load the vapic option rom from the firmware config interface.  With inb / movb, writing the vapic area happens in guest context, which the kernel is prepared to handle.  With insb, the write happens from kvm, which is then undone on the next entry, leading to the tpr being set to a high value.

Shouldn't the vapic area be mapped in on demand? Then we could map it on option rom init time and everyone's happy.

Alex

--
To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html


[Index of Archives]     [KVM ARM]     [KVM ia64]     [KVM ppc]     [Virtualization Tools]     [Spice Development]     [Libvirt]     [Libvirt Users]     [Linux USB Devel]     [Linux Audio Users]     [Yosemite Questions]     [Linux Kernel]     [Linux SCSI]     [XFree86]
  Powered by Linux