Phase E of the ACPI fork-sync plan. Two changes:
1. New methods on AcpiContext (Linux 7.1 best practices):
- transition_to_s_state(state): evaluates _TTS(state) AML method.
Mirrors Linux 7.1 acpi_sleep_tts_switch (drivers/acpi/sleep.c:36).
Called when the system transitions between sleep states, including
during shutdown. Failure is non-fatal: _TTS is optional per ACPI
spec.
- wake_from_s_state(state): evaluates _WAK(state) AML method.
Mirrors Linux 7.1 acpi_sleep_finish_wake (drivers/acpi/sleep.c).
Called by userspace on resume from a sleep state. The ACPI spec
requires the OS to call _WAK on the same state that was passed
to _PTS before the sleep.
- enter_sleep_state(state): top-level entry point that calls
_TTS (Step 0, Linux 7.1) then set_global_s_state (Steps 1-5,
Phase D). This is the public API that future kernel S3/S4 paths
should use.
2. DMAR init: previously disabled with `//TODO (hangs on real hardware)`
because MMIO reads (e.g. gl_sts.read()) on some real hardware block
or spin forever. Phase E.4 fix:
- Dmar::init() now calls Dmar::init_with(acpi_ctx, false) for
safety (no-op by default).
- New Dmar::init_with(acpi_ctx, opt_in) takes an explicit boolean
that callers can set to true.
- The DRHD iteration has a hard cap of 32 entries (real hardware
has 1-4 DRHDs) to prevent any infinite-iterator hang.
- The call site in init() reads REDBEAR_DMAR_INIT=1 from the
environment and passes that to Dmar::init_with.
This unblocks DMAR on QEMU and on hardware known to work, while
keeping it safe-by-default on real hardware where the hang is
reproducible.
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 07:11. QEMU boot reaches Red Bear login:
prompt cleanly with no errors. Both @inputd:661 and @ps2d:96
startup logs visible. redbear-sessiond working with login1
registered on D-Bus.
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).
Phase C of the ACPI fork-sync plan. Applies targeted gap fixes on top
of the synchronized fork foundation (commits 4f2a043 + ae57fe3).
Closes 4 of the 8 critical gaps identified by the 2026-06-30 ACPI
assessment.
Gap 5 - SLP_TYPb PM1b write (acpid/src/acpi.rs):
The previous code wrote SLP_EN+SLP_TYPa to PM1a but silently dropped
SLP_TYPb. On hardware that requires both PM1a and PM1b writes
(some laptops, server boards with split power blocks), the shutdown
was incomplete. Now writes SLP_EN+SLP_TYPb to PM1b when
pm1b_control_block is non-zero. The FADT field is 0 when no
second block exists, in which case we skip the second write.
Gap 6 - parse_lnk_irc range validation (hwd/src/backend/acpi.rs):
The previous code accepted any 16-bit integer as an IRQ
(n AND 0xFFFF), producing "Enabled at IRQ 53313" from misparsed
FieldUnit accessors on QEMU PIIX4. Now validates that the IRQ
value is 2047 or less (the maximum valid legacy-compatible IOAPIC
IRQ). Out-of-range values are debug-logged and skipped instead
of polluting the routing table. Also adds a 15-bit cap on the
Buffer-based IRQ bit extraction (was unchecked).
Gap 3 - AML mutex create/acquire/release (acpid/src/aml_physmem.rs):
The new gitlab acpi crate (Phase B bump) added proper Handler
trait methods for create_mutex, acquire, and release. The previous
implementation was three log debug stubs returning fake success,
which would silently corrupt AML state for any DSDT/SSDT that
uses Mutex. Now implements a real mutex table backed by
std::sync.Mutex of FxHashSet u32:
- create_mutex allocates a unique u32 handle from a counter
- acquire busy-waits with 1ms sleeps until the handle is free
or the AML timeout (multiplied by 1000 for ms to us conversion)
expires; returns AmlError::MutexAcquireTimeout on timeout
- release removes the handle from the held set
Gap 4a - set_global_s_state non-S5 explicit warning (acpid/src/acpi.rs):
The previous code silently returned early when called with any
state other than 5. Now emits a log warn with the requested
state, naming the missing dependencies (_PTS/_WAK AML evaluation,
P-state preservation, wakeup path). This converts a silent failure
into a diagnostic that is visible in the boot log.
Also includes drivers/acpid/src/dmi.rs:158 - convert e.errno
(private field) to e.errno() (method call). The libredox
Error struct changed its errno from a public field to a method
in a newer release; the DmiError::Map(syscall::error::Error)
construction was using the field-access form, which broke the
build against current libredox. This is a build-fix that the
prior dirty tree already had; included here to keep base
buildable.
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 05:28.
Red Bear OS