system stalls when wallclock/TOD nudged

[Colin Percival]

On 11/19/10 10:30, Larry Maloney wrote:
> Does your motherboard have a hardware watchdog timer?

Not one which is accessible from within a DomU. :-)

It seems that this bug is related somehow to the idle thread sleeping -- when
I comment out the call to idle_block from cpu_idle_hlt in i386/machdep.c the
stalling goes away.

> On Fri, 2010-11-19 at 06:42 -0800, Colin Percival wrote:
>> I'm seeing a weird bug here, and I'm wondering if anyone else has experienced
>> this and/or has any clue how to fix it.
>>
>> During the boot process, in the middle of running rc.d scripts, my FreeBSD/Xen
>> instance stalls.  It does nothing until I send a shutdown signal, at which point
>>> [XEN] hypervisor wallclock nudged; nudging TOD.
>> and a couple buffered lines of rc.d script output are printed.  From there the
>> rc.shutdown script starts running, but it too stalls after a short time; then I
>> see
>>> [XEN] hypervisor wallclock nudged; nudging TOD.
>>> Nov 19 14:08:33 init: timeout expired for /bin/sh on /etc/rc.shutdown: Interrupted system call; going to single user mode
>> printed, suggesting that the shutdown watchdog timer at least managed to not get
>> stuck even though everything else did.

-- 
Colin Percival
Security Officer, FreeBSD | freebsd.org | The power to serve
Founder / author, Tarsnap | tarsnap.com | Online backups for the truly paranoid