Re: [Xen-users] Quirky Bug: "cat /dev/urandom"

William Schaller
Tue, 14 Jun 2005 12:32:44 -0000

Here''s the scenario: I''m using two ssh windows to control the
box.
With one, I start xend, create the domain. With the other, I use xm
console to log into the domain. Logged into the domain, I exec cat
/dev/urandom. Predictably, the screen starts to fill with junk. At
this point, ctrl-c, nor any other method of escaping either cat or
this console will work. Attempting any command using xm or xend in the
other window simply hangs until I ctrl-c. Stopping and restarting xend
has no effect. I can kill the bash process the other window is
running, but if I reconnect to the console, I get the same garbage
dumping endlessly.

I discovered this while testing out the balloon driver. I was going to
cat /dev/urandom > file for a while until I had about 60 GB, then gzip
the file to see if I would get a OOM. But I left off the > file and
ended up with the above conundrum.

-Bill

On 6/14/05, Mark Williamson <mark.williamson@cl.cam.ac.uk>
wrote:
> Since Xend handles console output, splurging huge amounts of text to the
> console is probably breaking it. (which is still a known issue, AFAIK)
>
> Does the domain actually keep outputting to the console?  Can you
disconnect
> and reconnect to the console?  What happens then?
>
> Cheers,
> Mark
>
> On Tuesday 14 June 2005 10:45, aq wrote:
> > On 6/14/05, William Schaller <wschalle@gmail.com> wrote:
> > > If you execute cat /dev/urandom at the xm console of a guest
domain,
> > > it will spew garbage forever.
> >
> > one question: what do you expect to get from /dev/urandom?
> >
> > regards,
> > aq
> >
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