Re: HVM Migration of domU on Qemu-upstream DM causes stuck system clock with ACPI

[Alex Bligh <alex@alex.org.uk>]

--On 14 May 2013 14:11:20 +0100 Diana Crisan <dcrisan@flexiant.com> wrote:

> We are using Xen-4.3-rc1 with dom0 running Ubuntu Precise and
> 3.5.0-23-generic kernel, and domU running Ubuntu Precise (12.04) cloud
> images running 3.2.0-39-virtual. We are using the xl.conf below on
> qemu-upstream-dm and HVM and two identical sending and receiving machines
> (hardware and software)
>
> When live migration is instigated between two identical hardware
> configurations using 'xl migrate', the migrate completes but the system
> clock in domU appears to be stuck when the domU resumes on the receiving
> side. For instance, running 'top', 'date', or 'uptime' will constantly
> report the same result. The clocks in dom0 were synchronized before
> migration using ntpdate. A modification of the clock using the date
> command in the migrated domU solves the problem; migrating back to the
> original machine works, but after a third migration the problem
> reappears.

Stranger and stranger.

What happens after this migrate is that 'uptime' reports increasing uptime
(as in seconds since boot), but the date/time is always the same. Setting
date fixes this.

It appears that whatever the process is that updates wall time in the kernel
is not running, until tweaked by wall time being set manually.

-- 
Alex Bligh