feat(config): enable 8250/16550 serial for HV backend#6
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Enable CONFIG_SERIAL_8250 alongside the existing PL011 so the same kernel binary works with both VZ and HV backends: - VZ backend: uses PL011 (earlycon=pl011, console=ttyAMA0) - HV backend: uses ns16550a via vm-superio (earlycon=uart,mmio32, console=ttyS0) Both drivers are built-in (CONFIG_MODULES=n) so no initramfs module loading is needed. Kernel size impact is minimal (~20KB). Also enable CONFIG_SERIAL_OF_PLATFORM for FDT-based UART discovery.
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Pull request overview
This PR updates the ARM64 kernel configuration so a single ArcBox kernel binary can boot with a working serial console on both macOS Virtualization.framework (PL011) and the custom Hypervisor.framework backend (ns16550a/8250), and updates the developer docs accordingly.
Changes:
- Enable
CONFIG_SERIAL_8250+CONFIG_SERIAL_8250_CONSOLE(and related UART count settings) inconfigs/arcbox-arm64.config. - Document the dual-UART setup (PL011 for VZ, 8250/16550 for HV) in
CLAUDE.md.
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.
| File | Description |
|---|---|
| configs/arcbox-arm64.config | Enables 8250/16550 serial console support alongside existing PL011 settings for ARM64. |
| CLAUDE.md | Updates documented “key configs” to include the newly-required 8250 serial options for the HV backend. |
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Summary
Enable
CONFIG_SERIAL_8250+CONFIG_SERIAL_8250_CONSOLEin the ARM64 kernel config so the same kernel binary works with both Virtualization.framework (VZ) and Hypervisor.framework (HV) backends.Changes
configs/arcbox-arm64.config: Enable 8250/16550 serial alongside PL011CLAUDE.md: Update docs to mention both UART typesWhy
The custom HV backend (
arcbox-vmm darwin_hv) usesvm-superio's ns16550a UART instead of PL011. WithoutCONFIG_SERIAL_8250=y, the kernel cannot useearlycon=uart,mmio32,...orconsole=ttyS0with the HV backend.With this change:
console=ttyAMA0 earlycon=pl011,...(unchanged)console=ttyS0 earlycon=uart,mmio32,...(now works)Impact
CONFIG_MODULES=n)Test plan