Re: [Xen-devel] Re: 2.6.28.7 domU: 32-bit emulation seems to be broken

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

On 08/10/09 05:59, Christoph Egger wrote:
>> I still notice this problem with vanilla 2.6.30.4 domU under Xen 3.3.2
>> (32 bit binaries on a 64 bit domU kernel segfault, AMD CPU).  vdso32=0
>> still helps.
>>
>> Any news?
>>     
>
> What does Linux use w/o vdso32=0 on your box ? Does it use sysenter, syscall
> or int 0x80 ?
>
> Do you boot the DomU directly or does this happen after migration from
> an Intel box ?
>   

There appears to be a bug in the 64-bit xen_sysret32, which attempts to
take the sysret environment and turn it into an iret hypercall (since
iret is the only way to do a 64-bit kernel -> 32-bit user return).

I don't have an AMD test machine on hand, so I haven't had a chance to
work out what's actually failing.  I couldn't see anything wrong by
staring at the code, but that probably means I was either starting hard
at the bug, or looking right next to the bug...

Could you try looking at this?

    J

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel