Re: dom0 hang in xen-4.0.0-rc5 - possible acpi issue? [WAS: Using xen-unstable, dom0 hangs during boot]

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

> 
> Everything seems to work if I specify acpi_skip_timer_override in grub.conf.  I think I may be seeing the following issue:
> 
> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/272247?comments=all
> System freezes during boot, unless I hold a key down
> Ubuntu >> "linux" package >> Bugs >> Bug #272247
> 
> > The problem behind this seems not limited to a certain controller
> > chip, but related to ACPI BIOS definitions. The IRQ0 override
> > defines to which interrupt number the timer interrupt is supposed
> > to be routed. Most BIOS define a route to IRQ2, so the timer
> > source (hpet in most cases) has to deliver an IRQ2 whenever a
> > timer expires. The problem is, that this is not always correct
> > (either hpet does not use IRQ2 or IRQ2 is not enabled on the
> > chipset). So as soon as all CPUs go into sleep there is no
> > timer irq to wake them up. To solve this automatically one
> > would need documentation about the chipsets pci config space
> > which is often secret. 

Do you have the MCP67 chipset?
> >
> > Workaround for affected systems: Use of "acpi_skip_timer_override"
> > as kernel command line option. Sometimes "nohpet" or "acpi=noirq"
> > have been reported to work, too."
> 
> 
> Is there a way that I can verify that this is the issue?

Yes. You need to boot the pv-ops under bare-metal so that we can be sure
this is not a Xen hypervisor problem, but the pv-ops kernel having an
issue.

Please provide the serial output with debugging turned on (debug initcall_debug
apic=debug).

Thanks.