On Wed, 12 Aug 2020 at 00:44, Stefano Stabellini via Stratos-dev stratos-dev@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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