[vbox-dev] Possible bug in VB

[Sander van Leeuwen]

Larry,

Is there a bootable ISO available with this 11.3 kernel?

Thanks,

Sander

On 4/6/2010 10:30 PM, Larry Finger wrote:
> In http://bugzilla.novell.com/show_bug.cgi?id=576681, a problem with
> booting the openSUSE 11.3 Milestone kernels is discussed.
>
> The analysis of the problem is as follows (from Jiri Bohac):
>
> ===================
> I can now reproduce the problem as well. After more debugging I see that
> the machine is stuck in an endless loop of page faults.
>
> The page fault is triggered by the memset at fec0000 and the page fault
> is thought to be "spurious" (stale TLB entry) by the page fault handler,
> so the kernel does nothing, the STOS instruction of memset is restarted
> and the pagefault triggers again.
>
> The reason code for the page fault is 3, that is a protection fault
> during a write operation.
>
> Looking at the PMD entry and PTE of the fec00000 page, the page is set
> to be writeable, so I don't understand why this happens. The i386
> specification says that the TLB should be flushed automatically after a
> PF trap, and that is why the PF handler does nothing if it believes the
> PF was "spurious".
>
> So, this could either be a VB bug (because it is VB that emulates the
> paging, traps, etc in the guest), or there is some other reason why a
> page protection fault can happen besides the permission bits in the
> PTE/PMD entry.
> ===================
>
> My question is as follows: Does the i386 emulation handle this case
> correctly? If you are certain that it does, then the problem is with the
> kernel. As it happens, the only reports of this failure are on VMs
> running under VB.
>
> Larry
>
>
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>    


-- 
Kind regards / Mit freundlichen Gruessen / Met vriendelijke groet

--

Sun Microsystems GmbH        Sander van Leeuwen
Werkstrasse 24               Senior Staff Engineer, VirtualBox
71384 Weinstadt, Germany     mailto:Sander.Vanleeuwen at sun.com


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