Re: [Xen-devel] dom0 / hypervisor hang on dom0 boot

[Dietmar Hahn <dietmar.hahn@xxxxxxxxxxxxxx>]

Am Donnerstag 16 Mai 2013, 13:10:27 schrieb Jan Beulich:
> >>> On 16.05.13 at 13:07, Dietmar Hahn <dietmar.hahn@xxxxxxxxxxxxxx> wrote:
> > The function behind the pointer intel_private.driver->write_entry is
> > i965_write_entry(). And the interesting instruction seems to be:
> >   writel(addr | pte_flags, intel_private.gtt + entry);
> > 
> > I added another printk() on start of the function i965_write_entry().
> > And surprisingly  after printing a lot of messages the kernel came up!!!
> > But now I had other problems like losing the audio device (maybe timeouts).
> > So maybe the hang is a timing problem?
> 
> Apparently. As the caller is running this in a loop, did you check
> whether it's the first or always the same entry that it hangs on?

I did a fast check, did the first entry and a printk() and than the loop with
the other entries and the message  after the first entry was printed on the
serial log.

> > What I wanted to check is, what the hypervisor is doing while the system 
> > hangs.
> 
> Probably nothing in this case, as it doesn't get involved in the MMIO
> write being carried out.
> 
> > Has anybody an idea maybe a timer and after 30s printing a dump of the 
> > stack 
> > of all cpus?
> 
> That would be the watchdog, which you said doesn't kick in either.

Yes

> I'm afraid this is a problem with the graphics device's processing of
> the written data (locking up the machine at the bus level). Without
> help from someone knowing what the driver is supposed to do here,
> and what therefore might be going wrong, I don't see good chances
> of making progress here. Don - any idea who that could be?

I should mention that with openSuSE 12.2 and older all worked flawless.

Dietmar.



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