[Xen-ia64-devel] Re: No scheduling after domU launch

[Haavard Bjerke <havard.bjerke@xxxxxxx>]

I think I've found some leads to the most recent bug (dom0 freezes immediately, 
as opposed to after a short while). The problem seems to be somewhere within 
the cpu_raise_softirq() routine, which is called from bvt_wake() in 
sched_bvt.c. By not calling that routine when launching domU, I've managed to 
get control back to dom0 for a short while, after which it freezes as before. 
I'll look more into it tomorrow.

Håvard

On Wed, May 18, 2005 at 08:32:20AM -0700, Magenheimer, Dan (HP Labs Fort 
Collins) wrote:
> Given the previous discussion around this (last month?), I suspect
> that there is a bug somewhere that is overwriting some random
> memory related to the scheduler.  As Mark W pointed out, your
> previous workaround fixed a problem that should never happen.
> And I don't think any recent changes in xeno-unstable-ia64 have
> had anything to do with the scheduler, so I suspect the
> "random memory" moved to a different random spot which
> is causing your current problem.
> 
> This is just a theory... you are probably as familiar with this
> part of the code as anybody on this list right now.  Try
> adding some more printf's to see if any clues arise.
> I'll try to take a look but probably not today, so reply
> to this thread if you learn anything new or interesting.
> 
> Dan
> 
> > -----Original Message-----
> > From: Haavard Bjerke [mailto:havard.bjerke@xxxxxxx] 
> > Sent: Wednesday, May 18, 2005 9:23 AM
> > To: Magenheimer, Dan (HP Labs Fort Collins)
> > Cc: xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
> > Subject: No scheduling after domU launch
> > 
> > Since pulling the latest xeno-unstable-ia64 a few days ago, 
> > scheduling seems to stop immediately after launching domU, 
> > that is, domU continues to load, while dom0 stops because the 
> > scheduler is never entered again. This looks like the same 
> > problem as before, with dom0 freezing after domU launch; 
> > only, now it seems to freeze earlier. Before, I was able to 
> > run a hypercall right after launch. This is kind of critical, 
> > since a user-space app running in dom0 is supposed to 
> > establish a ctrl-channel right after launch, while domU is booting.
> > 
> > So I'm quite stuck and wondering why it stops scheduling, and 
> > I could use some input. So far I've found out that 
> > __enter_sceduler() is never called after domU launch, while 
> > the routine that's supposed to call that routine, 
> > ac_timer_softirq_action(), continues to be called. I think 
> > the __enter_sceduler() routine should be in a heap, but I 
> > don't understand why it would suddenly be removed from the heap..
> > 
> > Thanks,
> > Håvard
> > 

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