74 lines
1.9 KiB
C
74 lines
1.9 KiB
C
#include <def.h>
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#include "console.h"
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#include "multiboot2.h"
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#include "panic.h"
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#include "util.h"
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static void *multiboot_find_tag(uptr multiboot_info, u32 type) {
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uptr next = multiboot_info + 8;
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while (true) {
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multiboot_tag *tag = (multiboot_tag*)next;
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if (tag->type == MULTIBOOT_TAG_TYPE_END) {
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return NULL;
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}
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if (tag->type == type) {
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return tag;
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}
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next = align(next + tag->size, MULTIBOOT_TAG_ALIGN);
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}
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}
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#define MAX_REGIONS 64
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typedef struct {
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u64 base_address;
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u64 length;
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} region;
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extern uptr kernel_start;
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extern uptr kernel_end;
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static region regions[MAX_REGIONS] = {0};
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static size_t region_count = 0;
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static void find_memory_regions(uptr multiboot_info) {
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multiboot_tag_mmap *tag = multiboot_find_tag(multiboot_info, MULTIBOOT_TAG_TYPE_MMAP);
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if (tag == NULL) {
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boot_panic("Multiboot did not provide mmap tag");
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}
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u32 entry_count = (tag->size - 16) / tag->entry_size;
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u8 *entry_ptr = (u8*)tag->entries;
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for (u32 i = 0; i < entry_count; ++i) {
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multiboot_mmap_entry *entry = (multiboot_mmap_entry*)entry_ptr;
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if (entry->type == MULTIBOOT_MEMORY_AVAILABLE) {
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if (region_count >= MAX_REGIONS) {
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boot_panic("Too many memory regions");
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}
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regions[region_count++] = (region){ entry->base_address, entry->length };
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}
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entry_ptr += tag->entry_size;
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}
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}
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void c_start(u32 magic, uptr multiboot_info) {
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console_clear();
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if (magic != MULTIBOOT_BOOTLOADER_MAGIC) {
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boot_panic("Expected bootloader magic 0x%x, got 0x%x", MULTIBOOT_BOOTLOADER_MAGIC, magic);
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}
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find_memory_regions(multiboot_info);
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for (size_t i = 0; i < region_count; i++) {
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kprintf("Memory region %d: base=0x%X, length=0x%X\n", i, regions[i].base_address, regions[i].length);
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}
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} |