On Fri, Oct 05, 2018 at 02:57:03PM +0200, Dominik Csapak wrote: > On 10/5/18 10:38 AM, Daniel P. Berrangé wrote: > > On Fri, Oct 05, 2018 at 08:56:27AM +0200, Dominik Csapak wrote: > > > On 10/4/18 3:51 PM, Daniel P. Berrangé wrote: > > > > On Wed, Oct 03, 2018 at 11:13:43AM +0200, Dominik Csapak wrote: > > > > > this patch aims to execute a script when qemu exits > > > > > so that one can do cleanups when using --daemonize without > > > > > having to use the qmp monitor > > > > > > > > IMHO the idea of cleanup scripts run by QEMU itself is flawed. > > > > QEMU will inevitably crash before cleanup scripts can be run, > > > > so whatever mgmt app is using QEMU needs to be able to do > > > > cleanup without QEMU's help. > > > > > > > > I think this can be done more reliably with a wrapper script, > > > > that spawns QEMU, waits for it to exit and then calls the > > > > cleanup script. On Linux at least you can use prctl() with > > > > PR_SET_CHILD_SUBREAPER so you can detect exit'ing of QEMU > > > > even after it has daemonized. > > > > > > > > Perhaps we could have such a wrapper script put in the > > > > contrib directory > > > > > > > > Regards, > > > > Daniel > > > > > > > Hi, > > > > > > for cleaning up after qemu crashes, you are completely right, > > > (ignoring that the downscript for tap devices also never gets executed > > > then), but this series has another use. > > > > > > With it, a user can determine the reason of a graceful shutdown > > > (e.g., if it was by a signal, qmp or from inside) of qemu, > > > especially when using -no-reboot without using qmp > > > > > > and using qmp for that is not very practical for everyone, > > > or is there another way for that which i am missing? > > > > Honestly QMP *is* the right answer. We've put alot of effort into QMP > > and I don't think it is sensible to start adding new mechanisms to > > provide the same information in an adhoc manner. > > > > What makes you think QMP isn't practical to use ? We have client > > impls that talk to QMP in scripts/qmp that are just a few 100 lines > > of pretty simple python code. > > > > ok, i just found that having to start an extra program waiting for qmp > events might be overkill for some users > > nonetheless, i just found out that even with qmp, there is no way > to see if a machine started with '-no-reboot' was trying to reboot > or just shutting down, in both cases i got a SHUTDOWN event > with 'guest: true' > > would it make sense to send a patch that introduces a new data field > for the shutdown event that says if it was really a reset?
I had a feeling there was another way to detct it, but I'm not seeing it in QMP. So yeah, if this can't be determined, then I expect it is worth extending QMP to report this Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
