PureC-OS-ACPI

ACPI subsystem of PureC-OS: separate kernel module, compiled statically into the kernel image (same integration pattern as libxcrypt).

What it does

• RSDP / XSDT / RSDT discovery and checksum validation
• FADT parsing: PM1a/PM1b CNT blocks, SMI_CMD + ACPI_ENABLE, ResetReg/ResetValue (probed at FADT+110/+116, only a GAS that validates is trusted)
• ACPI mode enable (SCI_EN) — required on real laptops, otherwise PM1 writes are silently ignored
• DSDT _S5 parser (minimal, no AML engine): extracts SLP_TYPa/b for a spec-correct S5 shutdown
• Shutdown: ACPI S5 (parsed → 7 → 5) → QEMU q35/bochs ports → halt
• Reboot: ResetReg → keyboard controller → CF9 → triple fault
• Read-only MADT walk (LAPIC base, CPU/IOAPIC counts) + table dump via klog for bare-metal diagnostics
• Battery scan: BAT0..BAT3, PNP0C0A, AC (ACPI0003/ACAD/ADP1), _BIF/_BIX/_BST flags, SSDT enumeration, ECDT/PNP0C09. Dynamic values still UNKNOWN (BATTERY_PERCENT_UNKNOWN) — no AML executor yet.

Layout

• include/acpi/acpi.h — public API
• include/acpi/acpi_priv.h — shared private state (module-internal)
• src/acpi.c — init, table walk, GAS access, ACPI enable, dumps
• src/acpi_s5.c — _S5 parser
• src/acpi_power.c — shutdown / reboot sequences

Integration

src/kernel/Makefile compiles acpi/src/*.c with KERNEL_CFLAGS and -Iacpi/include -Isrc. Wiring to bootloader info (RSDP address + HHDM offset) lives in src/drivers/power/power.c (power_init()), the module itself takes them as acpi_init() args and includes no boot globals.

src/drivers/power/power.c is a thin wrapper: power_reboot(), power_shutdown() and battery reporting delegate to this module. Syscall numbers are unchanged (SYS_REBOOT 218, SYS_SHUTDOWN 219).

Bare-metal notes

• If shutdown still halts instead of powering off, read the serial log: acpi: _S5 parsed ... vs SLP_TYP 7/5 fallback lines tell whether firmware parsing or the PM1 write failed.
• ResetReg validated at FADT+... line tells which FADT layout your firmware uses.
• HW-reduced ACPI (no SMI_CMD / no PM blocks, some laptops): the module logs it and power ops degrade to legacy fallbacks.