Enables A20 (>1MB), loads rest of disk to 0x100000, jumps to 32-bit protected mode, enables paging. provides small stack growing down from 0x6000 (~20k), and jumps to kernel.
-
enables A20 line for >1MB
-
reads one sector at a time via int 13h/02
- (DEBUG) prints . for each sector
-
prints ! on sector read error
-
prints < if more than 10 errors
-
(DEBUG) prints > just before jumping to protected mode
-
loads GDT, jumps to protected mode
-
identity maps 4k-2MB pages
-
jumps to first file (kernel entry at 0x100020)
(page 0) 0x 0000 - 0x 07ff: real mode IDT and bios data (page 1) 0x 1000 - 0x 11ff: IDT (64 entries) 0x 1200 - 0x 1aff: ISR stage0 stubs (page 2) 0x 2000 - 0x 2003: parm stack pointer 0x 2004 - 0x 27ff: syscall parameter stack (grows down) 0x 2800 - 0x 28ff: 'syscall' table (page 3) : PDE (page 4) : PT0 (page 5) : application/kernel stack (grows down) (page 6) (page 7) 0x07000 - 0x07bff: TLS (gs register) 0x07c00 - 0x07dff: boot sector 0x07e00 - 0x07e67: TSS (1MB+) 0x100000-0x1fffff: disk sectors 1-? kernel loaded by bootloader 0x200000-0xf00000: 13MB free pages to allocate
0x0000: not present (to catch null references) 0x1000-2MB: 2MB identity mapped (kernel, stack, video memory) 0x 200000-0x f00000 : heap (automatically populated with bzeroed pages) 0x10000000-0xefffffff : ide0 mmap 0xf0000000-0xffbfffff : ide1 mmap 0xffc00000: all page tables 0xfffff000: page dir itself