Port useful ACPICA components into the existing Rust ACPI stack:
- LPIT (Low Power Idle Table) parser in new acpid/wake.rs.
Parses native C-state LPI entries (entry trigger, residency,
latency, residency counter, counter frequency). Computes total
residency and deepest LPI state. 4 unit tests cover parsing,
empty input, short input, and deepest-entry selection.
Reference: Linux include/acpi/actbl2.h struct acpi_lpit_native.
- _PRW wake device enumeration in acpid/wake.rs.
WakeRegistry::enumerate() evaluates _PRW on known wake-capable
device paths (LID, PWRB, SLPB, XHCI, HDAS, CNVW, I2C0/1, THC0/1).
Extracts GPE number and sleep state from the _PRW package.
Reference: Linux drivers/acpi/scan.c acpi_bus_get_wakeup_device_flags.
- FADT S0-idle detection: Fadt::supports_s0_idle() checks bit 21
(ACPI_FADT_LOW_POWER_S0) to detect platforms that support s2idle.
Reference: Linux include/acpi/actbl.h.
- acpid/main.rs: LPIT parse + wake enumeration + S0-idle detection
wired into init after AcpiContext::init() and before power events.
ACPICA assessment: do NOT port ACPICA as a C library. Port its
useful data structures and algorithms into the existing Rust stack
(acpi-rs vendored fork + acpid daemon). The AML interpreter already
has comprehensive opcode coverage (only DefLoad/DefLoadTable remain
unimplemented, both optional). The GPE/EC/fixed-event infrastructure
is already in acpid. LPIT + _PRW + S0-idle detection fill the
remaining gaps for Phase 9.1 s2idle completion.
Red Bear OS
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