[libvirt] [PATCH 8/9] libxl: pass cmdline to HVM guests

Ian Campbell ian.campbell at citrix.com
Mon Mar 23 10:26:51 UTC 2015


On Fri, 2015-03-20 at 22:13 +0100, Marek Marczykowski-Górecki wrote:
> I'll definitely do. But above raises a question - how can I set extra
> arguments for qemu? In case of qemu in dom0, it's not a problem because
> I can create some wrapper script. But in case of qemu in stubdom, the
> only way is to set b_info->extra_hvm. Some additional attributes for
> <emulator> tag?

There are several components, please can you be precise about which you
want to pass something to.

1. qemu process command line in dom0 (used e.g. for pv backends)
2. command line of the stubdom pv kernel itself
3. qemu "process" command line in stubdom
4. kernel command line in dom0

It's possible that libxl doesn't fully expose all 4 of those. I'm not
sure if #2 is actually useful but it seems like we would certainly want
to be able to expose the other 3 if possible.

b_info->cmdline should be #4, I'm pretty sure.

We also have b_info->extra, ->extra_pv and ->extra_hvm, but I'm not
entirely sure how these map onto #1 and #3.

I'm reasonably sure that ->extra maps to _both_ #1 and #3. It would seem
logical enough if ->extra_hvm mapped to #3 and ->extra_pv mapped to #1,
but I don't know if it actually works that way. It would probably be
quickest to confirm empirically.

With that I'll leave the mapping into livirt xml to others ;-)

Ian.





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