On Sun, 04/27 11:59, Michael S. Tsirkin wrote: > On Sun, Apr 27, 2014 at 09:34:06AM +0100, Peter Maydell wrote: > > On 27 April 2014 09:29, Michael S. Tsirkin <m...@redhat.com> 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 <f...@redhat.com> > > > > > > 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. > > OK so by using a wrong address an MMIO handler can e.g. start > MMIO on the device itself instead of doing DMA, > this will cause an infinite loop. > Any idea how to fix this? > > > 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 > > I agree, but I'd like the change to be done in a way that does not make > debugging harder. >
Michael, Why is debugging harder with this patch, please? Fam
