[kata-dev] Fast booting KVM guests w/o firmware and Qemu pc-lite

Maran Wilson maran.wilson at oracle.com
Mon Apr 2 20:40:37 UTC 2018

There was some discussion about Qemu pc-lite vs upstream Qemu in the 
Architecture Committee meeting today. As Jesse Butler briefly mentioned 
on Slack, a few of us have been working on upstreaming a different 
approach to starting KVM guests without firmware that should be more 
acceptable for upstream maintainers. We are treating it as a more 
general purpose interface, but hopefully this framework will go a long 
way towards closing the gap between pc-lite and upstream Qemu in terms 
of guest startup time for solutions like Kata containers.

We have already posted a set of Linux kernel patches upstream that seem 
to be well received so far by the community. See 
https://lkml.org/lkml/2018/3/20/717 for the latest version. We are 
currently working on cleaning up the corresponding Qemu patches and 
getting them ready for upstream review as well. Based on the RFC 
discussions we have had with upstream maintainers regarding high level 
design, I'm cautiously optimistic that we won't run into any deal 
breakers when we do post the qemu patches.

The high level idea is that we could use this approach to achieve the 
same goal of booting directly to the uncompressed Linux kernel (without 
running firmware), but in a way that is acceptable to the upstream 
community since we aren't introducing any new Linux OS specific 
(zero-page) initialization in Qemu.

So for anyone interested in the Qemu/KVM side of Kata containers and how 
we might be able to start VMs more quickly, please take a look at the 
patches we have posted so far and feel free to join the discussion on 
the upstream mailing lists.


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