diff options
Diffstat (limited to 'src/boot.S')
| -rw-r--r-- | src/boot.S | 24 |
1 files changed, 13 insertions, 11 deletions
@@ -38,9 +38,11 @@ stack_top: .section .pages, "aw", @nobits .align 4096 -boot_page_directory: +.global kernel_pagedir +kernel_pagedir: .skip 1024 * 4 -boot_page_table1: +.global kernel_ptable0 +kernel_ptable0: .skip 1024 * 4 @@ -55,8 +57,8 @@ boot_page_table1: _start: cli - # Physical address of boot_page_table1. - movl $(boot_page_table1 - VADDR_OFFSET), %edi + # Physical address of kernel_ptable0. + movl $(kernel_ptable0 - VADDR_OFFSET), %edi # Only map the kernel. mov $_kernel_start - VADDR_OFFSET, %esi @@ -75,14 +77,14 @@ l_page_init: # Size of page is 4096 bytes. addl $4096, %esi - # Size of entries in boot_page_table1 is 4 bytes. + # Size of entries in kernel_ptable0 is 4 bytes. addl $4, %edi # Loop to the next entry if we haven't finished. loop l_page_init map_vga: # Map VGA video memory to 0xC03FF000 as "present, writable". - movl $(0x000B8000 | 0x003), boot_page_table1 - VADDR_OFFSET + 1023 * 4 + movl $(0x000B8000 | 0x003), kernel_ptable0 - VADDR_OFFSET + 1023 * 4 /* Enabling paging does not change the next instruction, which continues to be physical. Therefore, map the kernel @@ -91,11 +93,11 @@ map_vga: - entry 1 starts 0x0040 0000 ends 0x007f ffff - entry 768 starts 0xc000 0000 ends 0xc03f ffff */ - movl $(boot_page_table1 - VADDR_OFFSET + 0x003), boot_page_directory - VADDR_OFFSET + 1 * 4 - movl $(boot_page_table1 - VADDR_OFFSET + 0x003), boot_page_directory - VADDR_OFFSET + 768 * 4 + movl $(kernel_ptable0 - VADDR_OFFSET + 0x003), kernel_pagedir - VADDR_OFFSET + 1 * 4 + movl $(kernel_ptable0 - VADDR_OFFSET + 0x003), kernel_pagedir - VADDR_OFFSET + 768 * 4 - # Set cr3 to the address of the boot_page_directory. - movl $(boot_page_directory - VADDR_OFFSET), %ecx + # Set cr3 to the address of the kernel_pagedir. + movl $(kernel_pagedir - VADDR_OFFSET), %ecx movl %ecx, %cr3 # Enable paging and the write-protect bit. @@ -113,7 +115,7 @@ map_vga: kinit: # At this point, paging is fully set up and enabled. # Unmap the identity mapping as it is now unnecessary. - movl $0, boot_page_directory + 1 * 4 + movl $0, kernel_pagedir + 1 * 4 # Reload crc3 to force a TLB flush so the changes to take effect. movl %cr3, %ecx movl %ecx, %cr3 |