The local/sources/kernel fork at 9f6a428 adds the
hardware-agnostic S3 entry path via direct PM1 register
write, mirroring Linux 7.1 acpi_hw_legacy_sleep in
drivers/acpi/acpica/hwsleep.c:81-127.
New acpi/fadt.rs module parses the FADT (signature
'FACP') to extract the PM1a_CNT and PM1a_STS IO port
addresses. ACPI 6.5 §5.2.9 / Table 5.6.
scheme/acpi.rs exposes S3_SLP_TYP (AtomicU8) and
kstop_set_s3_slp_typ() so acpid can pass the SLP_TYP
value from \_S3 to the kernel before requesting S3.
scheme/sys/mod.rs kstop handler parses 's3' (or 's3X'
where X is the SLP_TYP byte) and calls
kstop_set_s3_slp_typ() if X is provided. Default
S3 SLP_TYP=5 (standard for x86 systems).
arch/x86_shared/stop.rs enter_s3() is fully
implemented: clear WAK_STS, wbinvd, split-write
SLP_TYP then SLP_TYP|SLP_EN to PM1a_CNT. If S3
doesn't take (firmware refused), fall through to S5.
Hardware-agnostic: works for any platform with a
working FADT and standard PM1 register layout (Dell,
HP, Lenovo, LG Gram 14 (2022), etc.). Modern Standby-
only platforms (LG Gram 16 (2025)) don't expose S3
and the s3 path falls through to S5.
Phase II resume trampoline (the firmware jumps to
the FACS waking_vector; the kernel restores page
tables, long mode, registers) is NOT yet implemented.
The current S3 entry path works for systems that can
resume via the BIOS/UEFI wake path (which re-enters
Redox from cold boot, losing kernel state). A real
S3 resume requires the CPU state save + trampoline,
which is Phase II.X (deferred).
vasilito
1d3878ee78