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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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6
kernel/core/main.c
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@ -11,6 +11,7 @@
#include "dma.h"
#include "klog.h"
#include "usb.h"
#include "acpi.h"
static void *klog_base; // the persistent log, just above the kernel image
@ -294,6 +295,9 @@ kmain(uint32 fb_addr)
// and change nothing.
platform_register_devices(fb_addr);
pciuser_init();
// The firmware's AML, loaded before the bus is: pci_init() asks it where
// each device's interrupt really goes. See kernel/acpi/aml.c.
acpi_aml_init();
pci_init();
if (boot_verbose) cprintf("verbose boot: pci_init done\n");
@ -369,6 +373,8 @@ kmain(uint32 fb_addr)
// After the poller, which is what keeps a USB controller whose INTx
// never arrives working, and after the scheduler, which it sleeps in.
usb_hotplug_start();
// Where AML runs for the SCI: the power button, GPEs, notifications.
acpi_thread_start();
// The debugger's own thread, for the same reason netinit's comes after
// sinit: kthread_create needs a usable process table. From here on Ctrl-G
// on the console answers, with no filesystem mounted and nothing in