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acpi: uACPI, for interrupt routing, the power button and power-off

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The firmware's AML is now interpreted. uACPI 6.1.1 (MIT) is fetched by
ports/uacpi, checksum-verified, and compiled into the kernel unmodified,
the same way lwIP is. kernel/acpi/host.c is its host layer: memory,
mapping, port and PCI config I/O, time, mutexes and events that spin
before the scheduler exists, the SCI, and an "acpi" thread for the
work the SCI defers.

PCI interrupts go where the board says. pci_init() now routes every
device's INTx through the root bridge's _PRT before drivers bind. It
follows link devices' _CRS, uses a bridge's own _PRT where the namespace
has one, and swizzles through bridges that don't. Before this, INTx
waited on the 8259's line number, which is the wrong pin in APIC mode.
irq_register() takes a trigger mode rather than a level/low flag,
because q35's links and most SCIs are level, active-high. The MADT's
interrupt source overrides are now parsed, and are what places the SCI.

The power button syncs the filesystems and powers off. shutdown() and
reboot() go through the firmware's S5 and reset register first, and
only then fall back to the emulators' ports, which a real board does
not answer.

Tested under QEMU: q35 with MSI off routes xHCI to GSI 22,
level/active-high, and it takes real interrupts with nothing polled.
system_powerdown powers off q35 and i440fx (QEMU exits 0), and q35
with 4 CPUs boots from NVMe with USB hot-plug working alongside.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4
This commit is contained in:
Nexoniarz 2026-10-22 16:12:28 +02:00
commit 93f981c7ea
16 changed files with 1237 additions and 14 deletions
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10
include/irq.h
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@ -41,6 +41,16 @@ typedef void (*irq_handler_t)(void *arg);
// than ISA's (edge-triggered, active high). Getting this wrong does not fail
// cleanly: an edge-configured level interrupt fires once and then wedges,
// because the device keeps the line asserted and no further edge ever comes.
//
// It is a mode, not a flag. 0 and 1 are the two above, which is all a PCI or
// ISA device needs; the other two are what ACPI can say about a line -- q35's
// PCI links and most machines' SCI are level-triggered *active high*, and
// programming one active low leaves the pin reading as permanently asserted.
#define IRQ_EDGE_HIGH 0 // ISA
#define IRQ_LEVEL_LOW 1 // PCI INTx
#define IRQ_LEVEL_HIGH 2
#define IRQ_EDGE_LOW 3
#define IRQ_IS_LEVEL(m) ((m) == IRQ_LEVEL_LOW || (m) == IRQ_LEVEL_HIGH)
int irq_register(int irq, irq_handler_t fn, void *arg, const char *name,
int level_low);
void irq_unregister(int irq, irq_handler_t fn, void *arg);