Bootloader: Find root partition from GPT header
This commit is contained in:
parent
b4775fbe75
commit
aa4f3046ff
|
|
@ -41,7 +41,7 @@ puts:
|
|||
movb $0x0E, %ah
|
||||
movb $0x00, %bh
|
||||
|
||||
.puts_loop:
|
||||
.puts_loop:
|
||||
lodsb
|
||||
|
||||
test %al, %al
|
||||
|
|
@ -50,7 +50,7 @@ puts:
|
|||
int $0x10
|
||||
jmp .puts_loop
|
||||
|
||||
.puts_done:
|
||||
.puts_done:
|
||||
popw %ax
|
||||
popw %bx
|
||||
popw %si
|
||||
|
|
@ -155,7 +155,7 @@ find_gpt_partition_entry:
|
|||
# although read will fail with more than 0x80
|
||||
movw (gpt_header + 80), %cx
|
||||
|
||||
.loop_gpt_entries:
|
||||
.loop_gpt_entries:
|
||||
pushw %cx
|
||||
movw $16, %cx
|
||||
call memcmp
|
||||
|
|
@ -169,11 +169,11 @@ find_gpt_partition_entry:
|
|||
|
||||
loop .loop_gpt_entries
|
||||
|
||||
.no_gpt_partition_found:
|
||||
.no_gpt_partition_found:
|
||||
movb $0, %al
|
||||
ret
|
||||
|
||||
.gpt_partition_found:
|
||||
.gpt_partition_found:
|
||||
movb $1, %al
|
||||
ret
|
||||
|
||||
|
|
@ -186,11 +186,13 @@ stage1_main:
|
|||
|
||||
# setup stack
|
||||
movw %ax, %ss
|
||||
movw $0x7C00, %sp
|
||||
movl $0x7C00, %esp
|
||||
|
||||
# save boot disk number
|
||||
movb %dl, (boot_disk_number)
|
||||
|
||||
# FIXME: validate boot disk (needs size optizations)
|
||||
|
||||
# confirm that int 13h extensions are available
|
||||
clc
|
||||
movb $0x41, %ah
|
||||
|
|
@ -241,23 +243,23 @@ halt:
|
|||
hlt
|
||||
jmp halt
|
||||
|
||||
.no_int13h_ext:
|
||||
.no_int13h_ext:
|
||||
mov $no_int13_ext_msg, %si
|
||||
jmp print_and_halt
|
||||
|
||||
.read_failed:
|
||||
.read_failed:
|
||||
mov $read_failed_msg, %si
|
||||
jmp print_and_halt
|
||||
|
||||
.not_gpt_partition:
|
||||
.not_gpt_partition:
|
||||
mov $not_gpt_partition_msg, %si
|
||||
jmp print_and_halt
|
||||
|
||||
.no_bios_boot_partition:
|
||||
.no_bios_boot_partition:
|
||||
mov $no_bios_boot_partition_msg, %si
|
||||
jmp print_and_halt
|
||||
|
||||
.too_gpt_big_entries:
|
||||
.too_gpt_big_entries:
|
||||
mov $too_gpt_big_entries_msg, %si
|
||||
jmp print_and_halt
|
||||
|
||||
|
|
@ -341,12 +343,12 @@ print_backspace:
|
|||
decb %dl
|
||||
jmp .print_backspace_do_print
|
||||
|
||||
.print_backspace_go_line_up:
|
||||
.print_backspace_go_line_up:
|
||||
# decrease row and set column to the last one
|
||||
decb %dh
|
||||
movb $(SCREEN_WIDTH - 1), %dl
|
||||
|
||||
.print_backspace_do_print:
|
||||
.print_backspace_do_print:
|
||||
# set cursor position
|
||||
movb $0x02, %ah
|
||||
int $0x10
|
||||
|
|
@ -359,7 +361,7 @@ print_backspace:
|
|||
movb $0x02, %ah
|
||||
int $0x10
|
||||
|
||||
.print_backspace_done:
|
||||
.print_backspace_done:
|
||||
popa
|
||||
ret
|
||||
|
||||
|
|
@ -375,7 +377,7 @@ printnum:
|
|||
movw $printnum_buffer, %si
|
||||
xorw %cx, %cx
|
||||
|
||||
.printnum_fill_loop:
|
||||
.printnum_fill_loop:
|
||||
# fill buffer with all remainders ax % bx
|
||||
xorw %dx, %dx
|
||||
divw %bx
|
||||
|
|
@ -393,21 +395,21 @@ printnum:
|
|||
xchgw %dx, %cx
|
||||
subw %dx, %cx
|
||||
movb $'0', %al
|
||||
.printnum_pad_zeroes:
|
||||
.printnum_pad_zeroes:
|
||||
call putc
|
||||
loop .printnum_pad_zeroes
|
||||
|
||||
movw %dx, %cx
|
||||
|
||||
.printnum_print_loop:
|
||||
.printnum_print_loop:
|
||||
decw %si
|
||||
movb (%si), %al
|
||||
cmpb $10, %al
|
||||
jae 1f
|
||||
addb $'0', %al
|
||||
jmp 2f
|
||||
1: addb $('a' - 10), %al
|
||||
2: call putc
|
||||
1: addb $('a' - 10), %al
|
||||
2: call putc
|
||||
loop .printnum_print_loop
|
||||
|
||||
popa
|
||||
|
|
@ -423,15 +425,39 @@ isprint:
|
|||
cmpb $0x7E, %al
|
||||
ja .isprint_done
|
||||
cmpb %al, %al
|
||||
.isprint_done:
|
||||
.isprint_done:
|
||||
ret
|
||||
|
||||
|
||||
# check if drive exists
|
||||
# dl: drive number
|
||||
# return:
|
||||
# al: 1 if disk is usable, 0 otherwise
|
||||
drive_exists:
|
||||
pusha
|
||||
|
||||
movb $0x48, %ah
|
||||
movw $disk_drive_parameters, %si
|
||||
movw $0x1A, (disk_drive_parameters) # set buffer size
|
||||
|
||||
clc
|
||||
int $0x13
|
||||
jc .drive_exists_nope
|
||||
|
||||
popa
|
||||
movb $1, %al
|
||||
ret
|
||||
|
||||
.drive_exists_nope:
|
||||
popa
|
||||
movb $0, %al
|
||||
ret
|
||||
|
||||
|
||||
# fills memory map data structure
|
||||
# doesn't return on error
|
||||
# NO REGISTERS SAVED
|
||||
get_memory_map:
|
||||
pusha
|
||||
|
||||
movl $0, (memory_map_entry_count)
|
||||
|
||||
movl $0x0000E820, %eax
|
||||
|
|
@ -445,7 +471,7 @@ get_memory_map:
|
|||
# If first call returs with CF set, the call failed
|
||||
jc .get_memory_map_error
|
||||
|
||||
.get_memory_map_rest:
|
||||
.get_memory_map_rest:
|
||||
cmpl $0x534D4150, %eax
|
||||
jne .get_memory_map_error
|
||||
|
||||
|
|
@ -471,25 +497,23 @@ get_memory_map:
|
|||
# BIOS can indicate end of list by setting CF
|
||||
jnc .get_memory_map_rest
|
||||
|
||||
.get_memory_map_done:
|
||||
popa
|
||||
.get_memory_map_done:
|
||||
ret
|
||||
|
||||
.get_memory_map_error:
|
||||
.get_memory_map_error:
|
||||
movw $memory_map_error_msg, %si
|
||||
jmp print_and_halt
|
||||
|
||||
|
||||
# fills command line buffer
|
||||
# NO REGISTERS SAVED
|
||||
get_command_line:
|
||||
pusha
|
||||
|
||||
movw $command_line_enter_msg, %si
|
||||
call puts
|
||||
|
||||
movw $command_line_buffer, %di
|
||||
|
||||
.get_command_line_loop:
|
||||
.get_command_line_loop:
|
||||
call getc
|
||||
|
||||
cmpb $'\b', %al
|
||||
|
|
@ -513,7 +537,7 @@ get_command_line:
|
|||
|
||||
jmp .get_command_line_loop
|
||||
|
||||
.get_command_line_backspace:
|
||||
.get_command_line_backspace:
|
||||
# don't do anything if at the beginning
|
||||
cmpw $command_line_buffer, %di
|
||||
je .get_command_line_loop
|
||||
|
|
@ -526,42 +550,18 @@ get_command_line:
|
|||
|
||||
jmp .get_command_line_loop
|
||||
|
||||
.get_command_line_done:
|
||||
.get_command_line_done:
|
||||
# null terminate command line
|
||||
movb $0, (%di)
|
||||
|
||||
call print_newline
|
||||
|
||||
popa
|
||||
ret
|
||||
|
||||
|
||||
stage2_main:
|
||||
# clear screen and enter 80x25 text mode
|
||||
movb $0x03, %al
|
||||
movb $0x00, %ah
|
||||
int $0x10
|
||||
|
||||
# print hello message
|
||||
movw $hello_msg, %si
|
||||
call puts
|
||||
call print_newline
|
||||
|
||||
call get_memory_map
|
||||
call get_command_line
|
||||
|
||||
call print_newline
|
||||
|
||||
movw $start_kernel_load_msg, %si
|
||||
call puts
|
||||
call print_newline
|
||||
|
||||
movw $command_line_msg, %si
|
||||
call puts
|
||||
movw $command_line_buffer, %si
|
||||
call puts
|
||||
call print_newline
|
||||
|
||||
# print memory map from memory_map_entries
|
||||
# NO REGISTERS SAVED
|
||||
print_memory_map:
|
||||
movw $memory_map_msg, %si
|
||||
call puts
|
||||
call print_newline
|
||||
|
|
@ -572,7 +572,7 @@ stage2_main:
|
|||
movw $16, %bx
|
||||
movw $4, %cx
|
||||
|
||||
.loop_memory_map:
|
||||
.loop_memory_map:
|
||||
movb $' ', %al
|
||||
call putc
|
||||
call putc
|
||||
|
|
@ -619,10 +619,212 @@ stage2_main:
|
|||
decl %edx
|
||||
jnz .loop_memory_map
|
||||
|
||||
ret
|
||||
|
||||
|
||||
# find root disk and populate root_disk_drive_number field
|
||||
# NO REGISTERS SAVED
|
||||
find_root_disk:
|
||||
movb $0x80, %dl
|
||||
|
||||
.find_root_disk_loop:
|
||||
call drive_exists
|
||||
testb %al, %al
|
||||
jz .find_root_disk_not_found
|
||||
|
||||
# read GPT header
|
||||
xorw %bx, %bx
|
||||
movl $1, %eax
|
||||
movw $1, %cx
|
||||
movw $gpt_header, %di
|
||||
call read_from_disk
|
||||
|
||||
# confirm header (starts with 'EFI PART')
|
||||
cmpl $0x20494645, (gpt_header + 0)
|
||||
jne .find_root_disk_next_disk
|
||||
cmpl $0x54524150, (gpt_header + 4)
|
||||
jne .find_root_disk_next_disk
|
||||
|
||||
# compare disk GUID
|
||||
movw $root_disk_guid, %si
|
||||
movw $(gpt_header + 56), %di
|
||||
movw $16, %cx
|
||||
call memcmp
|
||||
testb %al, %al
|
||||
jz .find_root_disk_next_disk
|
||||
|
||||
movb %dl, (root_disk_drive_number)
|
||||
ret
|
||||
|
||||
.find_root_disk_next_disk:
|
||||
incb %dl
|
||||
jmp .find_root_disk_loop
|
||||
|
||||
.find_root_disk_not_found:
|
||||
movw $no_root_disk_msg, %si
|
||||
jmp print_and_halt
|
||||
|
||||
|
||||
# finds root partition from root disk
|
||||
# fills root_partition_entry data structure
|
||||
# NOTE: assumes GPT header is in `gpt_header`
|
||||
# NO REGISTERS SAVED
|
||||
find_root_partition:
|
||||
pushl %ebp
|
||||
movl %esp, %ebp
|
||||
subl $16, %esp
|
||||
|
||||
# esp + 0: 8 byte entry array lba
|
||||
movl (gpt_header + 72), %eax
|
||||
movl %eax, 0(%esp)
|
||||
movl (gpt_header + 76), %eax
|
||||
movl %eax, 4(%esp)
|
||||
# FIXME: check that bits 48-63 are zero
|
||||
|
||||
# esp + 8: 4 byte entries per sector
|
||||
xorl %edx, %edx
|
||||
movl $SECTOR_SIZE, %eax
|
||||
divl (gpt_header + 84)
|
||||
movl %eax, 8(%esp)
|
||||
|
||||
# esp + 12: 4 byte entries remaining
|
||||
movl (gpt_header + 80), %eax
|
||||
testl %eax, %eax
|
||||
jz .find_root_partition_not_found
|
||||
movl %eax, 12(%esp)
|
||||
|
||||
.find_root_partition_read_entry_section:
|
||||
movl 0(%esp), %eax
|
||||
movl 4(%esp), %ebx
|
||||
movw $1, %cx
|
||||
movb (root_disk_drive_number), %dl
|
||||
movw $sector_buffer, %di
|
||||
call read_from_disk
|
||||
|
||||
# ecx: min(entries per section, entries remaining)
|
||||
movl 8(%esp), %ecx
|
||||
cmpl 12(%esp), %ecx
|
||||
jae .find_root_partition_got_entry_count
|
||||
movl 12(%esp), %ecx
|
||||
|
||||
.find_root_partition_got_entry_count:
|
||||
# update entries remaining
|
||||
subl %ecx, 12(%esp)
|
||||
|
||||
# si: entry pointer
|
||||
movw $sector_buffer, %si
|
||||
|
||||
.find_root_partition_loop_entries:
|
||||
# temporarily save cx in dx
|
||||
movw %cx, %dx
|
||||
|
||||
# check that entry is used
|
||||
movw $16, %cx
|
||||
movw $zero_guid, %di
|
||||
call memcmp
|
||||
test %al, %al
|
||||
jnz .find_root_partition_next_entry
|
||||
|
||||
# compare entry guid to root guid
|
||||
movw $16, %cx
|
||||
addw $16, %si
|
||||
movw $root_partition_guid, %di
|
||||
call memcmp
|
||||
subw $16, %si
|
||||
|
||||
testb %al, %al
|
||||
jnz .find_root_partition_found
|
||||
|
||||
.find_root_partition_next_entry:
|
||||
|
||||
# restore cx
|
||||
movw %dx, %cx
|
||||
|
||||
# entry pointer += entry size
|
||||
addw (gpt_header + 84), %si
|
||||
loop .find_root_partition_loop_entries
|
||||
|
||||
# entry not found in this sector
|
||||
|
||||
# increment 8 byte entry array lba
|
||||
incl 0(%esp)
|
||||
jno .find_root_partition_no_overflow
|
||||
incl 4(%esp)
|
||||
|
||||
.find_root_partition_no_overflow:
|
||||
# loop to read next section if entries remaining
|
||||
cmpl $0, 12(%esp)
|
||||
jnz .find_root_partition_read_entry_section
|
||||
|
||||
.find_root_partition_not_found:
|
||||
movw $no_root_partition_msg, %si
|
||||
jmp print_and_halt
|
||||
|
||||
.find_root_partition_found:
|
||||
# copy entry to buffer
|
||||
movw $root_partition_entry, %di
|
||||
movw $128, %cx
|
||||
rep movsb
|
||||
|
||||
leavel
|
||||
ret
|
||||
|
||||
|
||||
stage2_main:
|
||||
# clear screen and enter 80x25 text mode
|
||||
movb $0x03, %al
|
||||
movb $0x00, %ah
|
||||
int $0x10
|
||||
|
||||
# print hello message
|
||||
movw $hello_msg, %si
|
||||
call puts; call print_newline
|
||||
|
||||
call get_memory_map
|
||||
call get_command_line
|
||||
|
||||
call print_newline
|
||||
|
||||
movw $start_kernel_load_msg, %si
|
||||
call puts; call print_newline
|
||||
|
||||
call print_memory_map
|
||||
|
||||
call find_root_disk
|
||||
movw $root_disk_found_msg, %si
|
||||
call puts; call print_newline
|
||||
|
||||
call find_root_partition
|
||||
movw $root_partition_found_msg, %si
|
||||
call puts; call print_newline
|
||||
|
||||
movw $16, %bx
|
||||
movw $2, %cx
|
||||
movw (root_partition_entry + 38), %ax; call printnum
|
||||
movw (root_partition_entry + 36), %ax; call printnum
|
||||
movw (root_partition_entry + 34), %ax; call printnum
|
||||
movw (root_partition_entry + 32), %ax; call printnum
|
||||
|
||||
movb $'-', %al; call putc
|
||||
movb $'>', %al; call putc
|
||||
|
||||
movw (root_partition_entry + 46), %ax; call printnum
|
||||
movw (root_partition_entry + 44), %ax; call printnum
|
||||
movw (root_partition_entry + 42), %ax; call printnum
|
||||
movw (root_partition_entry + 40), %ax; call printnum
|
||||
|
||||
jmp halt
|
||||
|
||||
|
||||
# These will be patched during bootloader installation
|
||||
root_disk_guid:
|
||||
.ascii "root disk guid "
|
||||
root_partition_guid:
|
||||
.ascii "root part guid "
|
||||
zero_guid:
|
||||
.quad 0
|
||||
.quad 0
|
||||
|
||||
hello_msg:
|
||||
.asciz "This is banan-os bootloader"
|
||||
|
||||
|
|
@ -639,6 +841,16 @@ memory_map_error_msg:
|
|||
start_kernel_load_msg:
|
||||
.asciz "Starting to load kernel"
|
||||
|
||||
root_disk_found_msg:
|
||||
.asciz "Root disk found!"
|
||||
no_root_disk_msg:
|
||||
.asciz "Root disk not found"
|
||||
|
||||
root_partition_found_msg:
|
||||
.asciz "Root partition found!"
|
||||
no_root_partition_msg:
|
||||
.asciz "Root partition not found"
|
||||
|
||||
stage2_end:
|
||||
|
||||
|
||||
|
|
@ -650,12 +862,24 @@ gpt_header:
|
|||
gpt_entry_data:
|
||||
.skip SECTOR_SIZE
|
||||
|
||||
sector_buffer:
|
||||
.skip SECTOR_SIZE
|
||||
|
||||
disk_drive_parameters:
|
||||
.skip 0x1A
|
||||
|
||||
disk_address_packet:
|
||||
.skip 16
|
||||
|
||||
printnum_buffer:
|
||||
.skip 10
|
||||
|
||||
root_disk_drive_number:
|
||||
.skip 1
|
||||
|
||||
root_partition_entry:
|
||||
.skip 128
|
||||
|
||||
memory_map_entry_count:
|
||||
.skip 4
|
||||
# 100 entries should be enough...
|
||||
|
|
|
|||
Loading…
Reference in New Issue