Re: [Xen-devel] Possible bug with huge unflushed console buffer

[Mark van Dijk <lists+xen@xxxxxxxxxxxxxx>]

Greetings,

> > The behaviour I encountered i.e. a system lock seems to suggest that
> > there was some kind of buffer overflow. And this can be achieved by
> > something as simple as 'iptables -I INPUT -j LOG'. Perhaps it is a
> > wise idea to consider xl console -c to clear the console's history,
> > then at least I could exit the console and clear unsent messages...
> 
> Is your VM logging to its virtual serial line? You could just not do
> that...

Correct, it is logging to the virtual serial line and you're right, I
could just not do that. But isn't that just a workaround?

I just think that if you emulate something like a serial line, it should
be emulated properly. Why don't we just discard the data that is sent
to a detached serial line? That's what bare metal servers do too, right?

> I think this is due to the guest's qemu-dm process stuffing its
> transmitted serial data into a pty, to be consumed by 'xl console',
> and if that doesn't happen the buffers fill up, serial processing
> stops, and we back up all the way to the guest.

Right. So the issue is only with the guest, not with the hypervisor.
That's a relief. :)

-- 
Stay in touch,
Mark van Dijk.               ,--------------------------------
----------------------------'        Fri Aug 10 09:11 UTC 2012
Today is Boomtime, the 3rd day of Bureaucracy in the YOLD 3178

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