Find and read ACPI tables

src/kernel/boot/kmain.c

@@ -7,6 +7,7 @@
 #include <interrupts.h>
 #include <process.h>
 #include <scheduler.h>
+#include <smp.h>
 
 void thread_function()
 {
@@ -30,6 +31,8 @@ void kmain(uint64_t multiboot_magic, void *multiboot_data)
 
   cpu_init();
 
+  acpi_init();
+
   struct process *p1 = new_process((void (*)(void))0x10000);
   procmm_brk(p1, (void *)0x10100);
   memcpy_to_p4(p1->P4, (void *)0x10000, (void *)(uintptr_t)thread_function, 100);

src/kernel/drivers/acpi.c

@@ -0,0 +1,81 @@
+#include <smp.h>
+#include <memory.h>
+#include <debug.h>
+
+struct rsdp
+{
+  uint8_t signature[8];
+  uint8_t checksum;
+  uint8_t OEMID[6];
+  uint8_t revision;
+  uint32_t rsdt;
+  uint32_t length;
+  uint64_t xsdt;
+  uint8_t checksum2;
+  uint8_t _[3];
+}__attribute__((packed));
+
+struct sdt
+{
+  uint8_t signature[4];
+  uint32_t len;
+  uint8_t revision;
+  uint8_t checksum;
+  uint8_t OEMID[6];
+  uint8_t table_ID[8];
+  uint32_t OEM_revision;
+  uint32_t creator;
+  uint32_t creator_rev;
+  uint8_t data[];
+}__attribute__((packed));
+
+static struct rsdp *find_rsdp()
+{
+  uintptr_t ebda_start = *(uint16_t *)P2V(0x40e);
+  uintptr_t ebda_end = ebda_start + 1024;
+
+  void *p = P2V(ebda_start);
+  while(p < P2V(ebda_end))
+  {
+    if(!memcmp(p, "RSD PTR ", 8))
+    {
+      debug_info("RSDP found at:%x\n", p);
+      return p;
+    }
+    p = incptr(p, 16);
+  }
+
+  p = P2V(0xE0000);
+  while(p < P2V(0xFFFFF))
+  {
+    if(!memcmp(p, "RSD PTR ", 8))
+    {
+      debug_info("RSDP found at:%x\n", p);
+      return p;
+    }
+    p = incptr(p, 16);
+  }
+
+  return 0;
+}
+
+static void parse_sdt(struct sdt *sdt, uint8_t revision)
+{
+  uint32_t *p32 = (void *)sdt->data;
+  uint64_t *p64 = (void *)sdt->data;
+  int entries = (sdt->len - sizeof(struct sdt)) / (revision ? 8 : 4);
+  for(int i = 0; i < entries; i++)
+  {
+    struct sdt *table = P2V(revision ? p64[i] : p32[i]);
+    debug_info("Found table: ");
+    debug_putsn((char *)table->signature, 4);
+    debug_printf("\n");
+  }
+}
+
+void acpi_init()
+{
+  struct rsdp *rsdp = find_rsdp();
+  struct sdt *s = P2V(rsdp->revision ? rsdp->xsdt : rsdp->rsdt);
+  parse_sdt(s, rsdp->revision);
+}

src/kernel/include/smp.h

@@ -0,0 +1,3 @@
+#pragma once
+
+void acpi_init();