[Stratos-dev] Project Stratos deliverables and STR-9

François Ozog francois.ozog at linaro.org
Mon Aug 17 15:45:57 UTC 2020

On Wed, 12 Aug 2020 at 00:44, Stefano Stabellini via Stratos-dev
<stratos-dev at op-lists.linaro.org> wrote:
> Hi all,
> I am writing this email in regards to Project Stratos following up on
> Mike's suggestion to clarify the deliverables.
> Project Stratos has three main deliverables:
> 1) type-1 hypervisor boot orchestration
> 2) VMM with safety island and Trust Zone components
> 3) refactored, optimized virtio
> We had a few discussions on the topics and I think we are all on the
> same page, but I thought it would be good to expand a bit on them and
> also get in your feedback on 3).
> 1) corresponds to STR-10. In the short term it means adding system
> device tree support for static hypervisors with a reference implementation
> in Xen. It involves adding support for virtual machines to the system
> device tree specification, and implement the specification in Xen.
> 2) corresponds to STR-11. The current wording is a bit confusing. We
> haven't settled on whether it should be based on Zephyr or based on
> Rust. I don't have a strong opinion either way but I have a preference
> for Zephyr. In any case, 2) is about having a non-Linux dom0 environment
> that can boot on the Cortex-As or out-of-cluster on the Cortex-Rs/Ms (to
> monitor VMs running on the Cortex-As.)
I am not sure there is an "exclusive or" between Zephyr and Rust. I
think we can think of VMMs as:
- Rust unikernel running in a cortex A partition
- Zephyr app
- Rust Zephyr app on  Cortex M
Are those possible targets ?
I also think that the Zephyr App is the most interesting step at present.
> 3) is about addressing some of virtio's limitations particularly evident
> with type-1 hypervisors. In the short term it means getting Virtio to
> run well with a type-1, Xen being the reference. In particular, this
> deliverable is expected to enable virtio backends to run well in an
> unprivileged virtual machine environment. (Today, the virtio backends
> have to run in an environment with privileges over the entire system.)
> 3) is supposed to correspond to STR-9, but actually I don't think
> STR-9's description matches the virtio deliverable that we have under
> Stratos. It looks like STR-9 comes from LBI-24, not from LBI-40.
> If my understanding is correct, should we create a new STR Jira ticket
> to cover 3)?
> Cheers,
> Stefano
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François-Frédéric Ozog | Director Linaro Edge & Fog Computing Group
T: +33.67221.6485
francois.ozog at linaro.org | Skype: ffozog

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