Re: [Qemu-devel] About the light VM solution!

[Stefan Hajnoczi <stefanha@redhat.com>]

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On Tue, Dec 05, 2017 at 03:00:10PM +0100, Paolo Bonzini wrote:
> On 05/12/2017 14:47, Stefan Hajnoczi wrote:
> > On Tue, Dec 5, 2017 at 1:35 PM, Paolo Bonzini <pbonzini@redhat.com> wrote:
> >> On 05/12/2017 13:06, Stefan Hajnoczi wrote:
> >>> On Tue, Dec 05, 2017 at 02:33:13PM +0800, Yang Zhong wrote:
> >>>> As you know, AWS has decided to switch to KVM in their clouds. This news make almost all
> >>>> china CSPs(clouds service provider) pay more attention on KVM/Qemu, especially light VM
> >>>> solution.
> >>>>
> >>>> Below are intel solution for light VM, qemu-lite.
> >>>> http://events.linuxfoundation.org/sites/events/files/slides/Light%20weight%20virtualization%20with%20QEMU%26KVM_0.pdf
> >>>>
> >>>> My question is whether community has some plan to implement light VM or alternative solutions? If no, whether our
> >>>> qemu-lite solution is suitable for upstream again? Many thanks!
> >>>
> >>> What caused a lot of discussion and held back progress was the approach
> >>> that was taken.  The basic philosophy seems to be bypassing or
> >>> special-casing components in order to avoid slow operations.  This
> >>> requires special QEMU, firmware, and/or guest kernel binaries and causes
> >>> extra work for the management stack, distributions, and testers.
> >>
> >> I think having a special firmware (be it qboot or a special-purpose
> >> SeaBIOS) is acceptable.
> > 
> > The work Marc Mari Barcelo did in 2015 showed that SeaBIOS can boot
> > guests quickly.  The guest kernel was entered in <35 milliseconds
> > IIRC.  Why is special firmware necessary?
> 
> I thought that wasn't the "conventional" SeaBIOS, but rather one with
> reduced configuration options, but I may be remembering wrong.

Marc didn't spend much time on optimizing SeaBIOS, he used the build
options that were suggested.  An extra flag can be added in
qemu_preinit() to skip slow init that's unnecessary on optimized
machines.  That would allow a single SeaBIOS binary to run both full and
lite systems.

Stefan

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