stage1: hdd bootsect: Properly guard against image being booted as floppy drive
This commit is contained in:
parent
110d2dc7d4
commit
d67ce23b77
@ -16,29 +16,24 @@ start:
|
|||||||
cld
|
cld
|
||||||
jmp 0x0000:.initialise_cs
|
jmp 0x0000:.initialise_cs
|
||||||
.initialise_cs:
|
.initialise_cs:
|
||||||
xor ax, ax
|
xor bx, bx
|
||||||
mov ds, ax
|
mov ds, bx
|
||||||
mov es, ax
|
mov es, bx
|
||||||
mov ss, ax
|
mov ss, bx
|
||||||
mov sp, 0x7c00
|
mov sp, 0x7c00
|
||||||
sti
|
sti
|
||||||
|
|
||||||
; Some BIOSes don't pass the correct boot drive number,
|
|
||||||
; so we need to do the job
|
|
||||||
.check_drive:
|
|
||||||
; Limine isn't made for floppy disks, these are dead anyways.
|
; Limine isn't made for floppy disks, these are dead anyways.
|
||||||
; So if the value the BIOS passed is <0x80, just assume it has passed
|
; So if the value the BIOS passed is <0x80, just assume it has passed
|
||||||
; an incorrect value
|
; an incorrect value.
|
||||||
test dl, 0x80
|
cmp dl, 0x80
|
||||||
jz .fix_drive
|
jae .continue
|
||||||
|
|
||||||
; Drive numbers from 0x80..0x8f should be valid
|
; Error out (BX zeroed out above)
|
||||||
test dl, 0x70
|
push 0xb800
|
||||||
jz .continue
|
pop es
|
||||||
|
mov dword [es:bx], 'F ! '
|
||||||
.fix_drive:
|
jmp err
|
||||||
; Try to fix up the mess the BIOS have done
|
|
||||||
mov dl, 0x80
|
|
||||||
|
|
||||||
.continue:
|
.continue:
|
||||||
; Make sure int 13h extensions are supported
|
; Make sure int 13h extensions are supported
|
||||||
|
Loading…
Reference in New Issue
Block a user