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convert MBR, VBR, & Stage2 to use a BSS section. #3

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Nivirx merged 25 commits from bss-setup into trunk 2024-10-13 18:05:19 -04:00
Conversation 0 Commits 25 Files Changed 15 +78 -21
1 changed files with 78 additions and 21 deletions
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99
src/stage2/stage2.nasm
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@@ -53,10 +53,17 @@ begin_text:
jmp short (init - $$) jmp short (init - $$)
nop nop
; dl = byte boot_drive
; si = word part_offset (active partition offset)
; bx = ptr PartTable_t partition_table
; dx = ptr FAT32_bpb_t fat32_bpb
ALIGN 4, db 0x90 ALIGN 4, db 0x90
init: init:
cli ; We do not want to be interrupted cli ; We do not want to be interrupted
;
; Zero BSS section
;
mov cx, (end_bss - begin_bss) ; count = bss length mov cx, (end_bss - begin_bss) ; count = bss length
mov ax, begin_bss mov ax, begin_bss
@@ -68,9 +75,10 @@ init:
cld cld
rep stosb ; zero bss section rep stosb ; zero bss section
; done zeroing BSS
mov ax, __STAGE2_SEGMENT ; configured segment mov ax, __STAGE2_SEGMENT ; set all our segments to the configured segment
mov ds, ax ; Set segment registers to 0 mov ds, ax ; *
mov es, ax ; * mov es, ax ; *
mov fs, ax ; * mov fs, ax ; *
mov gs, ax ; * mov gs, ax ; *
@@ -119,30 +127,50 @@ struc SteviaInfoStruct_t
endstruc endstruc
struc EarlyBootStruct_t struc EarlyBootStruct_t
.lba_packet resb LBAPkt_t_size .partition_table resb PartTable_t_size
.partition_table resb partition_table_SIZE .fat32_bpb resb FAT32_bpb_t_size
.fat32_bpb resb fat32_bpb_SIZE .fat32_ebpb resb FAT32_ebpb_t_size
.fat32_ebpb resb fat32_ebpb_SIZE
.fat32_nc_data resb fat32_nc_data_SIZE
endstruc endstruc
; bp - 2 : uint8_t boot_drive ; bp - 2 : byte boot_drive
; bp - 4 : uint16_t part_offset ; bp - 4 : word part_offset
; bp - 6 : ptr PartTable_t partition_table
; bp - 8 : ptr FAT32_bpb_t fat32_bpb
ALIGN 4, db 0x90 ALIGN 4, db 0x90
main: main:
lea ax, [bp - 2] lea ax, [bp - 2]
mov [boot_drive_ptr], ax mov [boot_drive_ptr], ax
lea ax, [bp - 4] lea ax, [bp - 4]
mov [partition_offset_ptr], ax ; setup pointers to boot_drive and partition offset on stack mov [partition_offset_ptr], ax ; setup pointers to boot_drive and partition offset on stack
mov byte [bp - 2], dl ; boot_drive (probably 0x80) mov byte [bp - 2], dl ; boot_drive (probably 0x80)
mov word [bp - 4], si ; partition_offset mov word [bp - 4], si ; partition_offset
mov word [bp - 6], bx ; partition_table
mov word [bp - 8], dx ; fat32_bpb
.check_sig:
mov eax, dword [STAGE2_SIG] mov eax, dword [STAGE2_SIG]
cmp eax, 0xDEADBEEF cmp eax, 0xDEADBEEF
je main.stage2_main je main.stage2_main
ERROR STAGE2_SIGNATURE_MISSING ERROR STAGE2_SIGNATURE_MISSING
.stage2_main: .stage2_main:
mov ax, PartTable_t_size
push ax
mov ax, [bp - 6] ; ptr partition_table
mov ax, partition_table
push ax
call kmemcpy ; copy partition table data
add sp, 0x6
mov ax, (FAT32_bpb_t_size + FAT32_ebpb_t_size) ; size in byte
push ax
mov ax, [bp - 8] ; start of bpb - 0x3 for the jump short main at the start
push ax
mov ax, fat32_bpb ; defined in memory.inc, destination
push ax
call kmemcpy ; copy bpb & ebpb to memory
add sp, 0x6
call SetTextMode call SetTextMode
call disable_cursor call disable_cursor
print_string HelloPrompt_cstr print_string HelloPrompt_cstr
@@ -163,6 +191,7 @@ main:
call InitFATDriver call InitFATDriver
print_string InitFATSYS_OK_cstr print_string InitFATSYS_OK_cstr
ERROR STEVIA_DEBUG_HALT
; ;
; Find first cluster of bootable file ; Find first cluster of bootable file
; ;
@@ -468,25 +497,53 @@ times ((512 - 4) - ($ -$$) ) db 0x90 ; nop
STAGE2_SIG: dd 0xDEADBEEF ; Signature to mark the end of the stage2 STAGE2_SIG: dd 0xDEADBEEF ; Signature to mark the end of the stage2
section .bss follows=.sign section .bss follows=.sign
align 512 align 512, resb 1
begin_bss: begin_bss:
stack_bottom: stack_bottom:
stack resb 4096 resb 4096
stack_top: stack_top:
stage2_main_redzone resb 32 stage2_main_redzone:
resb 32
SteviaInfo resd 4 align 16, resb 1
fat32_state resb FAT32_State_t_size partition_table resb PartTable_t_size
disk_buffer resb 512 align 16, resb 1
fat32_bpb resb FAT32_bpb_t_size
fat32_ebpb resb FAT32_ebpb_t_size
fat_buffer resb 512 align 16, resb 1
fat32_nc_data resb 16
dir_buffer resb 512 align 16, resb 1
lba_packet resb LBAPkt_t_size
fat_fsinfo resb 512 align 16, resb 1
SteviaInfo:
resd 4
align 16, resb 1
fat32_state:
resb FAT32_State_t_size
%define BIOSMemoryMap_SIZE 4096 align 16, resb 1
BIOSMemoryMap resb 4096 mbr_sector_data:
resb 512
vbr_sector_data:
resb 512
align 16, resb 1
disk_buffer:
resb 512
fat_buffer:
resb 512
dir_buffer:
resb 512
fat_fsinfo:
resb 512
align 16, resb 1
%define BIOSMemoryMap_SIZE 2048
BIOSMemoryMap:
resb 2048
end_bss: end_bss: