Well, nobody responded, so I went ahead and implemented what I described. It's quite the Rube Goldberg machine. The program in the vm that needs to trigger the checkpoint is running under another simulator inside the VM. So the best I can have it do is make a file as a signal. So I wrote a python script that waits for the signal file to appear, then runs: $ssh <host> "virsh qemu-monitor-command --hmp centos8_1 'savevm savestate1'" When the ssh command completes, the python script deletes the signal file and the original program proceeds.
This works... usually. I notice that the VM occasionally hangs for a few minutes when taking a checkpoint. Or sometimes the whole thing crashes with, "libvirt.libvirtError: Timed out during operation: cannot acquire state change lock (held by monitor=qemuDispatchDomainMonitorCommand)" If anyone has any ideas that might help, I'd be happy to hear them. 🙂 But I'm basically just publishing my results so far in case anyone else is interested. ________________________________ From: Leek, Jim Sent: Thursday, August 26, 2021 4:08 PM To: qemu-discuss@nongnu.org <qemu-discuss@nongnu.org> Subject: Take a checkpoint from inside of qemu I'm running CentOS 8 inside qemu via virt-manager. I would like a program running on the virtual machine to be able to trigger a savevm command on it's own VM. (This is for debugging purposes on the program being run in the VM.) The only way I can think of to do this is to have the program trigger a script that ssh's out of the guest, to the host, to trigger the savevm command. Something like this: guest$ ssh <host> "virsh qemu-monitor-command --hmp centos8_1 'savevm savestate1'" Is there any more straightforward method available? Thanks, Jim
