vmm: Introduce riscv64 architecture

[TimePrinciple]

Introduce riscv64 architecture.

Changes

Introduce riscv64 architecture support for vmm module.

Reason

Enable firecracker to work on RISC-V 64-bit platforms.

License Acceptance

By submitting this pull request, I confirm that my contribution is made under
the terms of the Apache 2.0 license. For more information on following Developer
Certificate of Origin and signing off your commits, please check
CONTRIBUTING.md.

PR Checklist

• If a specific issue led to this PR, this PR closes the issue.
• The description of changes is clear and encompassing.
• Any required documentation changes (code and docs) are included in this
  PR.
• API changes follow the Runbook for Firecracker API changes.
• User-facing changes are mentioned in CHANGELOG.md.
• All added/changed functionality is tested.
• New TODOs link to an issue.
• Commits meet
  contribution quality standards.

---

• This functionality cannot be added in rust-vmm.

[zulinx86]

Hello @TimePrinciple ,
Thank you for opening this PR.

Sorry, but we are not planning to support this feature into Firecracker at least in the near future, because we don't have RISC-V hardware in our testing infra to test the functionality continuously and we have not received much valid business use cases for it.

If you (or viewers) have a specific use case, could you share it with us? Based on the inputs, we may reconsider its validity :)

Thank you for your understanding.

[zulinx86]

Hello,

We are closing this issue for now because it is not currently planned.
We will come back to this PR if we receive enough business use cases for RISC-V support.

Thank you for your effort and understanding.

[TimePrinciple]

Hello,

We are closing this issue for now because it is not currently planned. We will come back to this PR if we receive enough business use cases for RISC-V support.

Thank you for your effort and understanding.

Sorry for my late response, I will continue to develop RISC-V architecture support until it is accepted by firecracker team. I wonder would it be a troube to remain opened as a draft :)

[zulinx86]

Yes, we can keep this PR opened as a draft :)
We won't be able to merge it into main without valid business use case, but we may be able to merge it into a feature branch.

Thanks.

[TimePrinciple]

Yes, we can keep this PR opened as a draft :) We won't be able to merge it into main without valid business use case, but we may be able to merge it into a feature branch.

Thanks.

How very kind, that's exactly what I'm expecting at this stage. I will keep developing and updating this work in a feature branch, and I believe this will be picked up one day by main branch when RISC-V is mature enough.

I'm currently working on supporting rust-vmm crates on RISC-V, and I will get back to this work when they are finished. And repurpose this PR to another branch by that time :)

[zulinx86]

We really appreciate your passion and effort to contribute to Firecracker!
And I really hope that RISC-V gets mature and many cloud vendors adopts it 🚀
Thanks!

[TimePrinciple]

Works migrated to #4819