Re: [Qemu-devel] [PATCH 1/3] virtio: Introduce VirtIODevice.broken

[Peter Maydell]

On 27 April 2014 09:29, Michael S. Tsirkin <address@hidden> wrote:
> On Tue, Apr 22, 2014 at 04:55:15PM +0800, Fam Zheng wrote:
>> If guest driver behaves abnormally, emulation code could mark the device
>> as "broken".
>>
>> Once "broken" is set, device emulation will typically wait for a reset
>> command and ignore any other operations, but it could also return error
>> responds. In other words, whether and how does guest know about this
>> error status is device specific.
>>
>> Signed-off-by: Fam Zheng <address@hidden>
>
> I'm assuming the idea is to make debugging guest drivers easier
> for people not familiar with qemu?

As a general rule, guests shouldn't be able to cause QEMU to
just randomly exit. We have a bunch of code in tree which does
handle guest errors this way, of course, but cleanups to fix it
are worth having. The benefits include that one duff device
driver doesn't take out your whole VM, that you have a chance
for a clean shutdown, and reboot might restore the operation of
the offending device.

There was a thread about this a little while back.

thanks
-- PMM