RFC: sidecar: allow openhcl_boot to specify a state per-cpu, and have openhcl_boot set that state for VPs that have mapped interrupts #2477
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…hcl_boot set that state for VPs that have mapped interrupts
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Pull request overview
This PR introduces a mechanism for openhcl_boot to specify per-CPU startup state, allowing it to control which CPUs are started by the sidecar kernel versus the main kernel. This optimization enables CPUs with mapped interrupts to be started immediately by the main kernel, avoiding unnecessary transitions.
Key changes:
- Adds
PerCpuStatestructure to track which CPUs should be started by sidecar - Updates sidecar initialization to respect per-CPU state overrides when specified
- Modifies the boot process to identify CPUs with mapped interrupts and keep them in the main kernel
Reviewed changes
Copilot reviewed 6 out of 6 changed files in this pull request and generated 5 comments.
Show a summary per file
| File | Description |
|---|---|
| openhcl/sidecar_defs/src/lib.rs | Defines PerCpuState structure and adds it to SidecarParams |
| openhcl/sidecar/src/arch/x86_64/init.rs | Updates sidecar init to apply per-CPU state overrides to cpu_status array |
| openhcl/openhcl_boot/src/sidecar.rs | Modifies sidecar startup and kernel command line generation to use per-CPU state |
| openhcl/openhcl_boot/src/main.rs | Initializes sidecar_cpu_overrides in test code |
| openhcl/openhcl_boot/src/host_params/mod.rs | Adds sidecar_cpu_overrides field to PartitionInfo |
| openhcl/openhcl_boot/src/host_params/dt/mod.rs | Identifies CPUs with mapped interrupts and configures them to stay in main kernel |
mattkur
commented
Nov 22, 2025
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DO NOT MERGE, TESTING IN PROGRESS
Experiment: ask the kernel to online any CPUs that will immediately get interrupts mapped, and ask sidecar
to online the rest.