Support paravirtualization

[Gustavo Niemeyer]

The initramfs being used with ubuntu-core images currently only works on full virtualization, with faked IDE/etc. That implies extra overhead. It should also support paravirtualization, with virtio SCSI/etc.

[Oliver Grawert (ogra)]

we only need to put the module names into modules/ubuntu-core-rootfs in the initramfs-tools-ubuntu-core package ... do you happen to know the required module names for this feature ?

[Gustavo Niemeyer (niemeyer)]

virtio_scsi is the obvious one. Not sure if there's anything else necessary. Might be a good idea to catch up with the cloud image maintainers and ask.

[Gustavo Niemeyer (niemeyer)]

Also virtio_net, virtio_blk, virtio_pci.. these are builtin in the standard Ubuntu images, so probably also builtin there?

[Seth Arnold (seth-arnold)]

virtio-rng too, please. Thanks.

[Mark Shuttleworth (sabdfl)]

On 08/07/16 18:52, Seth Arnold wrote:
> virtio-rng too, please. Thanks.

Shiver :)

[Oliver Grawert (ogra)]

@seth is -rng really needed inside the initrd ? (note that all modules are available later in the rootfs anyway and afaik we do not yet support snappy with full disk encryption, not even in VMs)

@gustavo i see 9pnet_virtio and caif_virtio (both networking apparently) when running find on a xenial kernel ... do we need any of this too ?

[Oliver Grawert (ogra)]

answering my last question myself ... given we have no netboot code at all ready in the snappy initrd, i guess we can skip the networking modules too for the moment (in the hope that we get to implement the split initrd before having netboot support and dont need it anyway in the generic initrd)

[Oliver Grawert (ogra)]

i have uploaded a fix now, the next kernel snaps on http://cdimage.ubuntu.com/ubuntu-core/xenial/daily-preinstalled/ should have the fixed initrd (20160714++)