|
|
|
|
@ -40,6 +40,7 @@ GPT_SECTORS_LOADED equ 0x16
|
|
|
|
|
GPT_CURRENT_LBA equ 0x18
|
|
|
|
|
STAGE2_GPT_ENTRY_ADDR equ 0x1a
|
|
|
|
|
|
|
|
|
|
main:
|
|
|
|
|
; Disable interrupts
|
|
|
|
|
cli
|
|
|
|
|
|
|
|
|
|
@ -71,7 +72,7 @@ STAGE2_GPT_ENTRY_ADDR equ 0x1a
|
|
|
|
|
mov di, 0x00
|
|
|
|
|
mov ah, 0x08
|
|
|
|
|
int 0x13
|
|
|
|
|
jc .panic
|
|
|
|
|
jc panic
|
|
|
|
|
; Load sectors per track into cx & spill
|
|
|
|
|
and cl, 0x3f
|
|
|
|
|
xor ch, ch
|
|
|
|
|
@ -84,14 +85,14 @@ STAGE2_GPT_ENTRY_ADDR equ 0x1a
|
|
|
|
|
; Load LBA 1.
|
|
|
|
|
mov ax, 1
|
|
|
|
|
mov bx, 0x7e00
|
|
|
|
|
call .read_lba
|
|
|
|
|
call read_lba
|
|
|
|
|
|
|
|
|
|
; Check the GPT header magic "EFI PART"
|
|
|
|
|
mov cx, GPT_MAGIC_LEN
|
|
|
|
|
mov si, gpt_magic
|
|
|
|
|
mov di, 0x7e00
|
|
|
|
|
repe cmpsb
|
|
|
|
|
jne .panic
|
|
|
|
|
jne panic
|
|
|
|
|
|
|
|
|
|
; Ensure the 8-byte GPT starting LBA fits in 16 bits
|
|
|
|
|
mov di, 0x7e00 ; The rep increments di so we need to reset it
|
|
|
|
|
@ -99,7 +100,7 @@ STAGE2_GPT_ENTRY_ADDR equ 0x1a
|
|
|
|
|
mov bx, [di + 0x4a]
|
|
|
|
|
or ax, bx
|
|
|
|
|
or eax, eax
|
|
|
|
|
jnz .panic
|
|
|
|
|
jnz panic
|
|
|
|
|
; Load and spill the GPT starting LBA
|
|
|
|
|
mov ax, [di + 0x48]
|
|
|
|
|
push ax
|
|
|
|
|
@ -123,9 +124,9 @@ STAGE2_GPT_ENTRY_ADDR equ 0x1a
|
|
|
|
|
; - If each entry is larger than a sector (512 bytes), they'll be sector-aligned.
|
|
|
|
|
; - If each entry is smaller than a sector, an integer number of them will fit into a sector.
|
|
|
|
|
or eax, eax ; Test size != 0 because 128 * 2^n != 0
|
|
|
|
|
jz .panic
|
|
|
|
|
jz panic
|
|
|
|
|
and eax, 127 ; Test size is a multiple of 128
|
|
|
|
|
jnz .panic
|
|
|
|
|
jnz panic
|
|
|
|
|
; Use the (n & (n - 1)) == 0 trick to test if the entry size is a power of 2. Since we already
|
|
|
|
|
; know it's a nonzero multiple of 128, if size is a power of 2 then size = 128 * 2^n holds.
|
|
|
|
|
; Therefore we don't need to bother dividing by 128 first (shr 7), which saves a couple of bytes.
|
|
|
|
|
@ -133,13 +134,13 @@ STAGE2_GPT_ENTRY_ADDR equ 0x1a
|
|
|
|
|
mov ecx, ebx
|
|
|
|
|
dec ecx
|
|
|
|
|
and ecx, eax
|
|
|
|
|
jnz .panic
|
|
|
|
|
jnz panic
|
|
|
|
|
|
|
|
|
|
; Find the "sector stride", which is the number of sectors we increment by each time we want to
|
|
|
|
|
; load a new entry.
|
|
|
|
|
shr eax, 9 ; Divide by sector size to get sectors per entry
|
|
|
|
|
cmp eax, 0xffff ; Make sure sectors per entry fits in 16 bits
|
|
|
|
|
ja .panic
|
|
|
|
|
ja panic
|
|
|
|
|
or ax, ax
|
|
|
|
|
jnz .gpt_sector_stride_loaded
|
|
|
|
|
; Sector stride must be at least one or we'll load the same sector each time!
|
|
|
|
|
@ -175,7 +176,7 @@ STAGE2_GPT_ENTRY_ADDR equ 0x1a
|
|
|
|
|
mov dx, [bp - GPT_CURRENT_ENTRY_IDX]
|
|
|
|
|
cmp [bp - GPT_N_ENTRIES_16], dx
|
|
|
|
|
; Panic if we've run out of partitions and haven't found the second stage yet.
|
|
|
|
|
jbe .panic
|
|
|
|
|
jbe panic
|
|
|
|
|
|
|
|
|
|
; If we haven't loaded any sectors yet, load the first one.
|
|
|
|
|
cmp word [bp - GPT_SECTORS_LOADED], 0
|
|
|
|
|
@ -192,7 +193,7 @@ STAGE2_GPT_ENTRY_ADDR equ 0x1a
|
|
|
|
|
; Read the current LBA to 0x8000 (just past the end of the GPT header)
|
|
|
|
|
mov ax, [bp - GPT_CURRENT_LBA]
|
|
|
|
|
mov bx, 0x8000
|
|
|
|
|
call .read_lba
|
|
|
|
|
call read_lba
|
|
|
|
|
; Increment number of sectors loaded
|
|
|
|
|
inc word [bp - GPT_SECTORS_LOADED]
|
|
|
|
|
|
|
|
|
|
@ -224,9 +225,9 @@ STAGE2_GPT_ENTRY_ADDR equ 0x1a
|
|
|
|
|
mov ebx, [si + 0x24]
|
|
|
|
|
; Ensure it fits in 16 bits.
|
|
|
|
|
or ebx, ebx
|
|
|
|
|
jnz .panic
|
|
|
|
|
jnz panic
|
|
|
|
|
cmp ebx, 0xffff
|
|
|
|
|
ja .panic
|
|
|
|
|
ja panic
|
|
|
|
|
; Load partition LBA end.
|
|
|
|
|
mov ecx, [si + 0x28]
|
|
|
|
|
mov edx, [si + 0x2c]
|
|
|
|
|
@ -235,11 +236,11 @@ STAGE2_GPT_ENTRY_ADDR equ 0x1a
|
|
|
|
|
or edx, edx
|
|
|
|
|
jnz .stage2_end_lba_ok
|
|
|
|
|
cmp eax, ecx
|
|
|
|
|
ja .panic
|
|
|
|
|
ja panic
|
|
|
|
|
.stage2_end_lba_ok:
|
|
|
|
|
|
|
|
|
|
mov bx, 0x8200
|
|
|
|
|
call .read_lba
|
|
|
|
|
call read_lba
|
|
|
|
|
jmp bx
|
|
|
|
|
|
|
|
|
|
; Load a single boot disk sector. Panic on failure.
|
|
|
|
|
@ -247,7 +248,7 @@ STAGE2_GPT_ENTRY_ADDR equ 0x1a
|
|
|
|
|
; - ax: LBA to load
|
|
|
|
|
; - bx: address to read sector to
|
|
|
|
|
; Clobber: ax, cx, dx
|
|
|
|
|
.read_lba:
|
|
|
|
|
read_lba:
|
|
|
|
|
; sector - 1 = LBA % sectors_per_track
|
|
|
|
|
; temp = LBA / sectors_per_track
|
|
|
|
|
; head = temp % n_heads
|
|
|
|
|
@ -270,10 +271,10 @@ STAGE2_GPT_ENTRY_ADDR equ 0x1a
|
|
|
|
|
mov al, 1
|
|
|
|
|
; Read sector
|
|
|
|
|
int 0x13
|
|
|
|
|
jc .panic
|
|
|
|
|
jc panic
|
|
|
|
|
ret
|
|
|
|
|
|
|
|
|
|
.panic:
|
|
|
|
|
panic:
|
|
|
|
|
mov ax, 0x0003
|
|
|
|
|
int 0x10
|
|
|
|
|
mov word fs:[0x0000], 0x4f21
|
|
|
|
|
@ -287,7 +288,7 @@ guid_stage2 db 0x69, 0xea, 0xff, 0xfd, 0x51, 0x36, 0x2f, 0x44, \
|
|
|
|
|
0xa1, 0x1d, 0x88, 0xa0, 0x9b, 0xf3, 0x72, 0xdd
|
|
|
|
|
GUID_LEN equ $ - guid_stage2
|
|
|
|
|
|
|
|
|
|
; MBR bootstrap field is 440 bytes long
|
|
|
|
|
%if ($ - $$) > 440
|
|
|
|
|
%error "exceeded mbr bootstrap field size"
|
|
|
|
|
%endif
|
|
|
|
|
; MBR bootstrap field is 440 bytes long
|
|
|
|
|
%if ($ - $$) > 440
|
|
|
|
|
%error "exceeded mbr bootstrap field size"
|
|
|
|
|
%endif
|
|
|
|
|
|
pantonshire
1 year ago