Trying cpr

["Dr. David Alan Gilbert" <dave@treblig.org>]

Hi Steve,
  I've just had a go with cpr-transfer, it's quite interesting.
I was just trying it on my (AMD) desktop.

* I was running with qemu displaying graphics, and after migration
the source display got updated every time I moved my mouse into the
source window; the VM was still stopped, but I guess that means
the source GUI is still parsing the guest VRAM and displaying it.
I'm not sure if there's any other interactions - e.g. is there any
situation where the source GUI will try and write into the shared
guest ram?

* Given that you pass fd's over the CPR socket, had you considered
passing main migration fd's over it as well, that way you'd
only need one incoming.

* The guest noticed the time skew:
  timekeeping watchdog on CPU1: Marking clocksource 'tsc' as unstable because the skew is too large:
     'kvm-clock' wd_nsec: 556248511 wd_new: 4a93129e69 wd_alst: 4a71eaf0aa mask: (all f's)
     'tsc' cs_nsec: 514023131 cs_now: 1047f1d8489 cs_last: 10414538c1 mask: (all f's)
     Clocksource 'tsc' skewed -42225380 ns (-42 ms) over watchdog 'kvm-clock' interval of 556248511 ns (556 ms)
     'kvm-clock' (not 'tsc') is current clocksource

  (That was hand copied, probably with some typos - who knew the
   GUI doesn't let you copy/paste from serial0...)


The source commandline was:
./try/qemu-system-x86_64  -object memory-backend-file,id=ram0,size=4G,mem-path=/dev/shm/qemuram0,share=on -m 4G -machine memory-backend=ram0,aux-ram-share=on -cpu host --enable-kvm -smp 16 -drive if=virtio,file=/discs/more/images/debian-13-nocloud-amd64-daily.qcow2 -qmp stdio

The dest commandline was:
./try/qemu-system-x86_64 -object memory-backend-file,id=ram0,size=4G,mem-path=/dev/shm/qemuram0,share=on -m 4G -machine memory-backend=ram0,aux-ram-share=on -cpu host --enable-kvm -smp 16 -drive if=virtio,file=/discs/more/images/debian-13-nocloud-amd64-daily.qcow2 -incoming tcp:0:44444 -incoming '{"channel-type": "cpr", "addr": { "transport": "socket", "type": "unix", "path": "cpr.sock"}}'

Dave
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