firecracker-microvm
Restore resource allocators from snapshot
What
Currently the ResourceAllocator is not restored from the snapshot, but its state is rebuilt by replaying allocations with ExactMatch (example).
Why
The current pattern for restoring the state is cumbersome and prone to error. For example, acpi and mptable allocations in the system memory are not replayed, meaning that the allocator state would be different after restore. It works fine for now because we don't allow for changing state after restore, but new features may be impacted by this, like hotplugging.
How
We should serialize its state in the snapshot, as proposed in https://github.com/rust-vmm/vm-allocator/pull/40, and remove the replayed ExactMatch allocations.
Additional Details
- https://github.com/firecracker-microvm/firecracker/pull/5139#discussion_r2059965612
The rust-vmm PR has been merged (https://github.com/rust-vmm/vm-allocator/pull/40), it will be possible to implement the firecracker side once it gets released.
@Manciukic Quick check in to see if the rust-vmm side was released? If so, I can take this issue on.
Hi @DakshinD. Yes, this was released in rust-vmm side. However, I needed this change for the PCIe feature branch that I am working on. So, I have brought in the necessary changes there. The changes are still in the PCI branch and they'll come in main branch when we merge PCI support.
