Re: [RFC] kvmtool: add support for modern virtio-pci

On 11/18/2015 03:22 AM, Gerd Hoffmann wrote:

/me goes undust the kvmtool patches for seabios.

(see https://www.kraxel.org/cgit/seabios/commit/?h=kvmtool,
build with CONFIG_KVMTOOL=y + CONFIG_DEBUG_LEVEL=9)

nilsson kraxel ~# ~kraxel/projects/kvmtool/lkvm run --name seabios
--firmware /home/kraxel/projects/seabios/out-bios-kvmtool/bios.bin
--disk /vmdisk/cloud/persistent/Fedora-Cloud-Base-22-20150521.x86_64.raw
  # lkvm run -k /boot/vmlinuz-3.10.0-324.el7.x86_64 -m 448 -c 4 --name
seabios

Thanks for testing! I didn't even thing about seabios as a testing target.

I tried to do what you described, and built seabios with:

$ cat .config | grep 'KVMTOOL\|DEBUG'
CONFIG_KVMTOOL=y
CONFIG_DEBUG_LEVEL=9

But when booting, it just hangs on:

$ ./lkvm run --firmware ~/seabios/out/bios.bin -d dummy
  # lkvm run -k /boot/vmlinuz-4.2.0-17-generic -m 448 -c 4 --name guest-12566


And same result with --virtio-legacy...

What did I miss?


Thanks,
Sasha

  Hi,

Thanks for testing! I didn't even thing about seabios as a testing target.

Not surprising, support isn't upstream, ran into a bunch of issues[1][2]
last time I tried to combine the two, ran into some issues and nobody
seemed to care, so the seabios patches where just sitting in a branch in
my repo ...

$ cat .config | grep 'KVMTOOL\|DEBUG'
CONFIG_KVMTOOL=y
CONFIG_DEBUG_LEVEL=9

Hmm, 'CONFIG_KVMTOOL=y > .config; make olddefconfig' should give you a
working configuration.

Setting 'CONFIG_DEBUG_LEVEL=9' is useful for trouble-shooting as it
makes the virtio drivers more verbose, but not mandatory to have.

Serial line support is needed to get output:

CONFIG_DEBUG_SERIAL=y
CONFIG_DEBUG_SERIAL_PORT=0x3f8

Also I think rom size must be 128k b/c kvmtool expects it to be that
way:

CONFIG_ROM_SIZE=128

But those are the defaults, and after "make olddefconfig" you should
already have them ...

cheers,
  Gerd

[1] kernel doesn't find pci (can be worked around by tweaking kernel
    command line in boot loader config).
[2] kernel virtio drivers fail to initialize (probably device reset
    not working properly).