Xen on Ubuntu: DomU hangs on boot

Allen Fowler allen.fowler at yahoo.com
Fri Nov 30 17:04:26 UTC 2007

> I've heard rumors that a DomU might hang when trying
> to access the
> hwclock. Try disabling the relevant start scrips /
> udev rules in the DomU.


I just checked a DomU (with new disk image) that I
left "hung" pegging the CPU at 99% for 6+ hours.

Guess what?  It finally booted, and "top" shows a
process 'hwclock' using all the CPU.

I was able to kill the process and the DomU CPU usage
fell to expected levels.

How do I disable the "hwclock" at boot up, and is it
safe to do so?  

What does "hwclock" do?

I am not at all familiar with the way Unix/Linux
handles the boot and startup process. 

> BTW: it would be nice if you could stop top posting.
> And it would be
> even nicer if you could get a mail client that
> doesn't break threading.

Sorry about that.. How is the treading now?  

I had switched to the new Yahoo Mail interface that
seems to not allow (?) in-line quoting.

p.s. I am going to also post this to the ubuntu-server
list, as it would seem relevant for those users, too. 

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