On Tue, Jan 10, 2023 at 04:20:59PM +0600, Oleg Vasilev wrote: > > > On 10.01.2023 15:09, Martin Kletzander wrote: > > On Tue, Jan 10, 2023 at 09:03:40AM +0000, Daniel P. Berrangé wrote: > > > On Tue, Jan 10, 2023 at 02:42:34PM +0600, Oleg Vasilev wrote: > > > > Serial log file contains lots of useful information for debugging > > > > configuration problems. It makes sense to preserve the log in between > > > > restarts, so that one can later figure out what was going on. Before > > > > that, we could do that on a per-domain basis, now we can configure it > > > > once for all domains. > > > > > > IMHO this is the job of the mgmt app that is using libvirt. > > > > > > We've got a few places in qemu.conf that interact with the > > > guest config, but I largely consider them to be historical > > > mistakes that shouldn't be added to. > > > > > > Adding this setting specifically for serial devs is opening > > > up a can of worms IMHO. eg what if you have multiple serial > > > ports and only want one of them in append mode. There are > > > many other devices with chardev backends which log to files, > > > but this setting only touches serial ports. > > What would be other cases with chardev file backends worth considering? I don't want to consider adding even more cases to the qemu.conf. > > > Ultimately append/truncate is a policy decision for the > > > mgmt app to make, not a libvirt host level tunable. > > > > > > > I agree with that since it allows for more configurability and it is > > concentrated in one place, the mgmt app. Defaulting to a value is > > something that should not be difficult to implement in any controlling > > application that uses libvirt, so I don't really see the benefit for > > other mgmt apps either. > > The issue here is that we have a 5 different management apps, and we would > have to introduce this change to all of them. These are in different > technology stacks, different languages, so it would be more complex to > duplicate the implementation of this feature. If you have 5 different mgmt apps then I feel a simple boolean flag for the <serial> console configuration when provisioning a guest should be negligible in the big picture. I don't think the answer is to push policy logic from the apps into libvirt via qemu.conf. > Another use case for this, similar to the one I had during my previous > experience in Huawei. I was given multiple libvirt's XMLs to debug issues > with boot. No management app was involved, except initial creation through > virt-install by third party. It would be beneficial to automatically retain > serial logs to ease the debugging process. If debugging a VM without a mgmt app being involved, it is trivial to use 'virsh edit' add the flag to the XML. With 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 :|
