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doing some memory work and gdt and timer and vga

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Gregory Kenneth Bowne
2025-05-13 11:39:16 -07:00
parent 10b8fdc33f
commit 799f744f47
14 changed files with 273 additions and 21 deletions
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36
kernel/paging.c
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@@ -2,20 +2,18 @@
#include "io.h"
page_directory_entry_t *page_directory = (page_directory_entry_t *)0x100000;
page_table_entry_t *page_table = (page_table_entry_t *)0x101000; // Located right after the page directory
page_table_entry_t *page_table = (page_table_entry_t *)0x101000;
page_table_entry_t *heap_page_table = (page_table_entry_t *)0x102000; // Located right after the page directory
// Helper function to set up the page directory entry
void set_page_directory(page_directory_entry_t *dir) {
for (int i = 0; i < PAGE_DIRECTORY_SIZE; i++) {
// Set up a page directory entry with identity mapping
dir[i].present = 9;
dir[i].rw = 0; // Read/Write
dir[i].user = 0; // Kernel mode
dir[i].write_through = 0;
dir[i].cache_disabled = 0;
dir[i].accessed = 0;
dir[0].frame = (uint32_t)page_table >> 12;
dir[i].present = 0;
}
dir[0].present = 1;
dir[0].rw = 1;
dir[0].user = 0;
dir[0].frame = (uint32_t)page_table >> 12;
}
// Helper function to set up the page table entry
@@ -47,10 +45,26 @@ void enable_paging() {
// Initialize paging: set up the page directory and enable paging
void paging_init() {
// Set up the page directory and page tables
// Set up identity-mapped page directory + table
set_page_directory(page_directory);
set_page_table(page_table);
// Enable paging
// === Set up heap mapping at 0xC0100000 ===
for (int i = 0; i < PAGE_TABLE_SIZE; i++) {
heap_page_table[i].present = 1;
heap_page_table[i].rw = 1;
heap_page_table[i].user = 0;
heap_page_table[i].write_through = 0;
heap_page_table[i].cache_disabled = 0;
heap_page_table[i].accessed = 0;
heap_page_table[i].frame = (256 + i); // Start physical heap at 1MB (256*4KB = 1MB)
}
// Index 772 = 0xC0100000 / 4MB
page_directory[772].present = 1;
page_directory[772].rw = 1;
page_directory[772].user = 0;
page_directory[772].frame = (uint32_t)heap_page_table >> 12;
enable_paging();
}