rr does not support KVM

[agentzh]

The command I ran is like this:

rr record qemu-system-x86_64 -kernel /boot/vmlinuz-`uname -r` \
    -nographic \
    -enable-kvm \
    -drive 'format=raw,file=qemu-image.img' \
  -append "root=/dev/sda rw console=ttyS0"

Running it immediately fails and gives the following (full) output:

https://gist.github.com/agentzh/e543dd7ff46697fc860411a4e54757ee

If I remove the -enable-kvm option from the command above, then I can successfully record the whole kernel booting and shutdown process and the replay also works beautifully as well.

Is it possible for rr to have support for the KVM API based on ioctl? Many thanks!

[agentzh]

Oh, forgot to provide more information about my environment:

• Ubuntu Linux 16.04 x86_64 running directly on metal (Intel NUC).
• Using Ubuntu's own kernel 4.4.0-134-generic.
• Using the rr built myself from the latest git master branch as of this writing (commit 7872e55a).
• Using the qemu built myself from the official 3.0.0 release tarball.

[rocallahan]

That would mean reocrd-and-replay support for KVM guests. It might be doable but it would probably require kernel changes and is certainly not a simple change to rr.

[agentzh]

@rocallahan Thanks for your quick reply! Right, it does not look easy.