2.6.37 dom0 under Xen 4.1 clocksource not working

[Daniel De Graaf <dgdegra@tycho.nsa.gov>]

When booting 2.6.37 (from kernel.org) under Xen 4.1, there are
apparently issues with timer interrupts being delivered to the dom0.
Repeatedly causing an interrupt (for example, the ACPI power button) will
allow the system to boot, as does adding "clocksource=jiffies" to the
kernel command line. This is only present under Xen, not when booting the
same kernel on real hardware.

When boot with clocksource=jiffies, the system will sometimes freeze
for about 30 seconds and then continue; however, this could be related
to kernel debugging that I have enabled.

The only clock-related message in dmesg is:
[  153.483813] Clocksource tsc unstable (delta = -77312555973 ns)

/sys/devices/system/clocksource/clocksource0/available_clocksource:
  xen jiffies tsc

I can attach kernel config or other information as required. I have
observed this on at least two platforms; the 2.6.32.x xen kernels do not
exhibit this behavior.

-- 
Daniel De Graaf
National Security Agency