ARM64 Support Status

Upstream Tracking

PR #3270 — "Add the initial Arm64 support"

Field	Value
PR	asterinas#3270
Author	@wanywhn
Branch	wanywhn/asterinas:arm64-support
State	OPEN, not merged
Mergeable	❌ Dirty (conflicts with current main)
Size	+4,475 / -49 lines, 80 files, 29 commits
Code origin	LLM-generated (author confirmed)
Author commitment	Will NOT maintain long-term
Upstream takeover	@lrh2000 plans to integrate with his own arm port

What the PR Adds

OSTD (ostd/src/arch/aarch64/):

boot/ — BSP entry, boot page tables
mm/ — ARM64 page tables (4-level paging), MMU setup
task/ — Context switching, FPU/SIMD save/restore
irq/ — GICv3 interrupt controller (uses third-party crate)
timer/ — ARM Generic Timer (EL1 physical)
trap/ — EL1 exception handling (sync/IRQ/FIQ/SError)
cpu/ — CPU features, SMP via PSCI
iommu/ — IOMMU stub
device/ — Device discovery via FDT
io/ — MMIO abstraction
power.rs — PSCI power management (shutdown/reboot)
serial.rs — PL011 UART console

Kernel (kernel/src/arch/aarch64/):

Process / thread support
Syscall table (EL0 → EL1)
TLS handling (TPIDR_EL0)
PCI enumeration
VirtIO support
TLB flush bugfix in KVirtArea::drop()

OSDK:

Raw ARM64 Image format for QEMU Linux boot protocol
Arm64 QEMU scheme in OSDK.toml
GitHub Actions CI for arm64 lint + compile

kei's Strategy

kei merges this branch via git (not patches). This means:

The full ostd/src/arch/aarch64/ tree exists in kei's repo
We can modify any file directly
Upstream sync is git merge, not quilt push
When upstream eventually merges a different arm64 implementation, we rebase our BSP on top of the new arch code

Known Issues in the arm64-support Branch

Issue	Severity	kei Action
All code LLM-generated	High	M2 audit: review every file, fix artifacts
Third-party GICv3 crate	Medium	Replace with in-tree driver
QEMU-only testing	High	Real hardware boot on NanoPi R3S
No SMP/multi-core	Medium	Add PSCI secondary CPU bring-up
Stale (behind upstream main)	Low	Regular sync rebase
LLM-style verbose comments	Low	Clean up during audit

QEMU Test Matrix

QEMU Machine	CPU	RAM	Boot	Notes
virt	cortex-a55	2GB	✅	Primary test target
virt	cortex-a72	2GB	🔲	Validate across ARM cores
virt	max	4GB	🔲	Enable all ARM features
sbsa-ref	max	4GB	🔲	Server-style boot