Phase D of the ACPI fork-sync plan.
Refactors acpi.rs set_global_s_state to follow the canonical Linux 7.1
pattern from drivers/acpi/acpica/hwxfsleep.c:283 (acpi_enter_sleep_state):
1. Look up the _Sx package in the AML namespace, extract SLP_TYPa
and SLP_TYPb (was previously hardcoded to _S5).
2. Evaluate _PTS(state) AML method (Prepare To Sleep) via the new
aml_evaluate_simple_method helper. Failure is non-fatal: _PTS is
optional per ACPI spec.
3. Evaluate _SST(sst_value) AML method (System Status indicator)
with the ACPI_SST_* constants (working=0, sleeping=1,
sleep-context=2, indicator-off=7).
4. Write SLP_EN|SLP_TYPa to PM1a, SLP_EN|SLP_TYPb to PM1b.
5. Spin (machine should power off before this returns).
Also adds:
- Generic aml_evaluate_simple_method(path, arg) helper that
mirrors Linux 7.1 acpi_execute_simple_method (drivers/acpi/utils.c).
Uses evaluate_if_present so missing methods return Ok(None) cleanly
instead of AmlError::ObjectDoesNotExist. Takes the AML global
lock with timeout 16 (mirroring the existing aml_eval pattern).
- Removes the hardcoded `if state != 5` early-return; the function
now handles any S-state generically. S1-S4 paths still don't
fully work (no _WAK, no P-state preservation, no wakeup vector),
but the new generic structure means a future _WAK implementation
only needs to add wakeup handling after step 4.
- Keeps the existing SLP_TYPb write (from Phase C) for hardware that
requires both PM1a and PM1b writes.
Combined with the existing scheme.rs change (thermal_zones() and
power_adapters() methods that enumerate _TZ and PowerResource
entries from the AML namespace), this completes the major ACPI
subsystem gaps identified by the 2026-06-30 assessment:
- Gap #1 RSDP validation (closed in Phase A)
- Gap #3 AML mutex stubs (closed in Phase C)
- Gap #4 set_global_s_state genericity + _PTS + _SST (closed here)
- Gap #5 SLP_TYPb write (closed in Phase C)
- Gap #6 parse_lnk_irc range validation (closed in Phase C)
- Gap #7 thermal/power enumeration (closed in Phase C)
- Gap #8 AcpiScheme fevent (closed in Phase A)
Remaining open:
- Gap #2 DMAR init (needs real-hardware investigation)
- Gap #4b _WAK infrastructure for real S1-S4 suspend (the
generic Sx scaffolding is now in place; _WAK + wakeup vector
+ P-state preservation are still TBD)
Verified by: CI=1 ./local/scripts/build-redbear.sh redbear-mini
succeeded with exit 0. ISO at build/x86_64/redbear-mini.iso
(512 MB) at 2026-06-30 06:28. QEMU boot reaches Red Bear login:
prompt cleanly with redbear-sessiond working (login1 registered
on D-Bus, ACPI shutdown watcher no longer errors).
Red Bear OS
8140a2cd27