Bootloader: Implement VESA video mode query and pass it to kernel

Kernel now gets framebuffer from bootloader. Framebuffer dimensions
and bpp are hardcoded in bootloader, but will probably be read from
config file at some point.

bootloader/CMakeLists.txt

@@ -6,7 +6,9 @@ set(BOOTLOADER_SOURCES
 	boot.S
 	command_line.S
 	disk.S
+	elf.S
 	ext2.S
+	framebuffer.S
 	memory_map.S
 	utils.S
 )

bootloader/boot.S

@@ -53,8 +53,14 @@ stage2_main:
 	movw $hello_msg, %si
 	call puts; call print_newline
 
+	call enter_unreal_mode
+	movw $unreal_enter_msg, %si
+	call puts; call print_newline
+
 	call get_memory_map
 	call read_user_command_line
+	
+	call vesa_find_video_mode
 
 	call print_newline
 
@@ -74,11 +80,91 @@ stage2_main:
 	jz print_and_halt
 
 	call ext2_find_kernel
+	movl $ext2_inode_read_bytes, %esi
 
-	jmp halt
+	call elf_read_kernel_to_memory
+
+	call vesa_set_target_mode
+
+	cli
+
+	# setup protected mode
+	movl %cr0, %ebx
+	orb $1, %bl
+	movl %ebx, %cr0
+
+	# jump to kernel in protected mode
+	ljmpl $0x18, $protected_mode
+
+
+.code32
+protected_mode:
+	movw $0x10, %bx
+	movw %bx, %ds
+	movw %bx, %es
+	movw %bx, %fs
+	movw %bx, %gs
+	movw %bx, %ss
+
+	movl %eax, %ecx
+
+	movl $0xD3C60CFF, %eax
+	movl $banan_boot_info, %ebx
+	xorl %edx, %edx
+	xorl %esi, %esi
+	xorl %edi, %edi
+
+	jmp *%ecx
+
+
+.code16
+enter_unreal_mode:
+	cli
+	pushw %ds
+
+	lgdt gdtr
+
+	movl %cr0, %eax
+	orb $1, %al
+	movl %eax, %cr0
+	ljmpl $0x8, $.enter_unreal_mode_pmode
+
+ .enter_unreal_mode_pmode:
+	movw $0x10, %bx
+	movw %bx, %ds
+
+	andb 0xFE, %al
+	movl %eax, %cr0
+	ljmpl $0x0, $.enter_unreal_mode_unreal
+
+ .enter_unreal_mode_unreal:
+	popw %ds
+	sti
+
+	ret
 
 hello_msg:
 	.asciz "This is banan-os bootloader"
 
+unreal_enter_msg:
+	.asciz "Entered unreal mode"
+
 start_kernel_load_msg:
 	.asciz "Starting to load kernel"
+
+gdt:
+	.quad 0x0000000000000000
+	.quad 0x00009A000000FFFF
+	.quad 0x00CF92000000FFFF
+	.quad 0x00CF9A000000FFFF
+gdtr:
+	.short . - gdt - 1
+	.quad gdt
+
+banan_boot_info:
+	boot_command_line:
+		.long command_line
+	boot_framebuffer:
+		.long framebuffer
+	boot_memory_map:
+		.long memory_map

bootloader/command_line.S

@@ -6,10 +6,20 @@
 # NO REGISTERS SAVED
 .global read_user_command_line
 read_user_command_line:
+	# print initial command line
 	movw $command_line_enter_msg, %si
 	call puts
+	movw $command_line_buffer, %si
+	call puts
 
+	# prepare registers for input
+	movw $command_line_enter_msg, %si
 	movw $command_line_buffer, %di
+ .read_user_command_line_goto_end:
+	cmpb $0, (%di)
+	jz .read_user_command_line_loop
+	incw %di
+	jmp .read_user_command_line_goto_end
 
  .read_user_command_line_loop:
 	call getc
@@ -23,9 +33,13 @@ read_user_command_line:
 	cmpb $'\n', %al
 	je .read_user_command_line_done
 
+	pushw %ax
+
 	call isprint
 	testb %al, %al
-	jnz .read_user_command_line_loop
+	jz .read_user_command_line_loop
+
+	popw %ax
 
 	# put byte to buffer
 	movb %al, (%di)
@@ -61,9 +75,9 @@ read_user_command_line:
 command_line_enter_msg:
 	.asciz "cmdline: "
 
-
-.section .bss
-
+.global command_line
+command_line:
 # 100 character command line
 command_line_buffer:
-	.skip 100
+	.ascii "root=/dev/sda2"
+	.skip 100 - 28

bootloader/elf.S

@@ -0,0 +1,222 @@
+.set SECTOR_SIZE,	512
+
+# file header field offsets
+.set e_type,		16
+.set e_machine,		18
+.set e_version,		20
+.set e_entry,		24
+.set e_phoff,		32
+.set e_shoff,		40
+.set e_flags,		48
+.set e_ehsize,		52
+.set e_phentsize,	54
+.set e_phnum,		56
+.set e_shentsize,	58
+.set e_shnum,		60
+.set e_shstrndx,	62
+
+# e_ident offsets
+.set EI_CLASS,		4
+.set EI_DATA,		5
+.set EI_VERSION,	6
+
+# e_ident constants
+.set ELFMAGIC,		0x464C457F
+.set ELFCLASS64,	2
+.set ELFDATA2LSB,	1
+.set EV_CURRENT,	1
+
+# e_type constants
+.set ET_EXEC,		2
+
+# program header field offsets
+.set p_type,		0
+.set p_flags,		4
+.set p_offset,		8
+.set p_vaddr,		16
+.set p_paddr,		24
+.set p_filesz,		32
+.set p_memsz,		40
+.set p_align,		48
+
+# p_type constants
+.set PT_NULL,		0
+.set PT_LOAD,		1
+
+.code16
+.section .stage2
+
+# Validate file header stored in elf_file_header
+# returns only on success
+elf_validate_file_header:
+	cmpl $ELFMAGIC, (elf_file_header)
+	jne .elf_validate_file_header_invalid_magic
+
+	cmpb $ELFCLASS64, (elf_file_header + EI_CLASS)
+	jne .elf_validate_file_header_only_64bit_supported
+
+	cmpb $ELFDATA2LSB, (elf_file_header + EI_DATA)
+	jne .elf_validate_file_header_only_little_endian_supported
+
+	cmpb $EV_CURRENT, (elf_file_header + EI_VERSION)
+	jne .elf_validate_file_header_not_current_version
+
+	cmpl $EV_CURRENT, (elf_file_header + e_version)
+	jne .elf_validate_file_header_not_current_version
+
+	cmpw $ET_EXEC, (elf_file_header + e_type)
+	jne .elf_validate_file_header_not_executable
+
+	ret
+
+ .elf_validate_file_header_invalid_magic:
+	movw $elf_validate_file_header_invalid_magic_msg, %si
+	jmp print_and_halt
+ .elf_validate_file_header_only_64bit_supported:
+	movw $elf_validate_file_header_only_64bit_supported_msg, %si
+	jmp print_and_halt
+ .elf_validate_file_header_only_little_endian_supported:
+	movw $elf_validate_file_header_only_little_endian_supported_msg, %si
+	jmp print_and_halt
+ .elf_validate_file_header_not_current_version:
+	movw $elf_validate_file_header_not_current_version_msg, %si
+	jmp print_and_halt
+ .elf_validate_file_header_not_executable:
+	movw $elf_validate_file_header_not_executable_msg, %si
+	jmp print_and_halt
+
+
+# read callback format
+#	eax: first byte
+#	ecx: byte count
+#	edi: buffer
+# returns only on success
+
+
+# reads kernel to memory
+#	esi:	callback for reading from kernel image
+# return:
+#	eax:	kernel entry address
+.global elf_read_kernel_to_memory
+elf_read_kernel_to_memory:
+	pushal
+	pushl %ebp
+	movl %esp, %ebp
+	subl $2, %esp
+
+	# read file header
+	movl $0, %eax
+	movl $64, %ecx
+	movl $elf_file_header, %edi
+	call *%esi
+
+	call elf_validate_file_header
+
+	cmpl $0, (elf_file_header + e_phoff + 4)
+	jnz .elf_read_kernel_to_memory_unsupported_offset
+
+	# current program header
+	movw $0, -2(%ebp)
+
+ .elf_read_kernel_to_memory_loop_program_headers:
+	movw -2(%ebp), %cx
+	cmpw (elf_file_header + e_phnum), %cx
+	jae .elf_read_kernel_to_memory_done
+
+	# eax := program_header_index * e_phentsize + e_phoff
+	xorl %eax, %eax
+	movw %cx, %ax
+	xorl %ebx, %ebx
+	movw (elf_file_header + e_phentsize), %bx
+	mull %ebx
+	addl (elf_file_header + e_phoff), %eax
+	jc .elf_read_kernel_to_memory_unsupported_offset
+
+	# setup program header size and address
+	movl $56, %ecx
+	movl $elf_program_header, %edi
+
+	# read the program header
+	call *%esi
+
+	# test if program header is empty
+	cmpl $PT_NULL, (elf_program_header + p_type)
+	je .elf_read_kernel_to_memory_null_program_header
+
+	# confirm that the program header is loadable
+	cmpl $PT_LOAD, (elf_program_header + p_type)
+	jne .elf_read_kernel_to_memory_not_loadable_header
+
+	# memset p_filesz -> p_memsz to 0
+	movl (elf_program_header + p_filesz), %ebx
+
+	movl (elf_program_header + p_vaddr),  %edi
+	andl $0x7FFFFFFF, %edi
+	addl %ebx, %edi
+
+	movl (elf_program_header + p_memsz),  %ecx
+	subl %ebx, %ecx
+	jz .elf_read_kernel_to_memory_memset_done
+
+ .elf_read_kernel_to_memory_memset:
+	movb $0, (%edi)
+	incl %edi
+	decl %ecx
+	jnz .elf_read_kernel_to_memory_memset
+ .elf_read_kernel_to_memory_memset_done:
+
+	# read file specified in program header to memory
+	movl (elf_program_header + p_offset), %eax
+	movl (elf_program_header + p_vaddr),  %edi
+	andl $0x7FFFFFFF, %edi
+	movl (elf_program_header + p_filesz), %ecx
+
+	#call print_hex32; call print_newline
+
+	call *%esi
+
+ .elf_read_kernel_to_memory_null_program_header:
+	incw -2(%ebp)
+	jmp .elf_read_kernel_to_memory_loop_program_headers
+
+ .elf_read_kernel_to_memory_done:
+	leavel
+	popal
+
+	# set kernel entry address
+	movl (elf_file_header + e_entry), %eax
+	andl $0x7FFFFF, %eax
+
+	ret
+
+ .elf_read_kernel_to_memory_unsupported_offset:
+	movw $elf_read_kernel_to_memory_unsupported_offset_msg, %si
+	jmp print_and_halt
+ .elf_read_kernel_to_memory_not_loadable_header:
+	movw $elf_read_kernel_to_memory_not_loadable_header_msg, %si
+	jmp print_and_halt
+
+
+elf_validate_file_header_invalid_magic_msg:
+	.asciz "ELF: file has invalid ELF magic"
+elf_validate_file_header_only_64bit_supported_msg:
+	.asciz "ELF: file is not targettint 64 bit"
+elf_validate_file_header_only_little_endian_supported_msg:
+	.asciz "ELF: file is not in little endian format"
+elf_validate_file_header_not_current_version_msg:
+	.asciz "ELF: file is not in current ELF version"
+elf_validate_file_header_not_executable_msg:
+	.asciz "ELF: file is not an executable"
+
+elf_read_kernel_to_memory_unsupported_offset_msg:
+	.asciz "ELF: unsupported offset (only 32 bit offsets supported)"
+elf_read_kernel_to_memory_not_loadable_header_msg:
+	.asciz "ELF: kernel contains non-loadable program header"
+
+.section .bss
+
+elf_file_header:
+	.skip 64
+
+elf_program_header:
+	.skip 56

bootloader/ext2.S

@@ -232,8 +232,8 @@ ext2_read_inode:
 	addl $ext2_block_buffer, %esi
 	  # edi := ext2_inode_buffer
 	movl $ext2_inode_buffer, %edi
-	  # cx := inode_size
-	movw (ext2_inode_size), %cx
+	  # ecx := inode_size
+	movl (ext2_inode_size), %ecx
 	rep movsb
 
 	popal
@@ -245,7 +245,10 @@ ext2_read_inode:
 # return:
 #	eax:	block index
 ext2_data_block_index:
+	pushl %ebx
 	pushl %ecx
+	pushl %edx
+	pushl %esi
 
 	# calculate max data blocks
 	movl (ext2_inode_buffer + i_size), %ecx
@@ -260,13 +263,87 @@ ext2_data_block_index:
 	# check if this is direct block access
 	cmpl $12, %eax
 	jb .ext2_data_block_index_direct
+	subl $12, %eax
 
-	jmp .ext2_data_block_index_unsupported
+	# check if this is singly indirect block access
+	cmpl $(EXT2_BLOCK_SIZE / 4), %eax
+	jb .ext2_data_block_index_singly_indirect
+	subl $(EXT2_BLOCK_SIZE / 4), %eax
+
+	# check if this is doubly indirect block access
+	cmpl $((EXT2_BLOCK_SIZE / 4) * (EXT2_BLOCK_SIZE / 4)), %eax
+	jb .ext2_data_block_index_doubly_indirect
+	subl $((EXT2_BLOCK_SIZE / 4) * (EXT2_BLOCK_SIZE / 4)), %eax
+
+	# check if this is triply indirect block access
+	cmpl $((EXT2_BLOCK_SIZE / 4) * (EXT2_BLOCK_SIZE / 4) * (EXT2_BLOCK_SIZE / 4)), %eax
+	jb .ext2_data_block_index_triply_indirect
+
+	# otherwise this is invalid access
+	jmp .ext2_data_block_index_invalid
 
  .ext2_data_block_index_direct:
-	movl $(ext2_inode_buffer + i_block), %ecx
-	addl %eax, %ecx
-	movl (%ecx), %eax
+	movl $(ext2_inode_buffer + i_block), %esi
+	movl (%esi, %eax, 4), %eax
+	jmp .ext2_data_block_index_done
+
+ .ext2_data_block_index_singly_indirect:
+	movl %eax, %ebx
+	movl (ext2_inode_buffer + i_block + 12 * 4), %eax
+	movw $1, %cx
+	jmp .ext2_data_block_index_indirect
+
+ .ext2_data_block_index_doubly_indirect:
+	movl %eax, %ebx
+	movl (ext2_inode_buffer + i_block + 13 * 4), %eax
+	movw $2, %cx
+	jmp .ext2_data_block_index_indirect
+
+ .ext2_data_block_index_triply_indirect:
+	movl %eax, %ebx
+	movl (ext2_inode_buffer + i_block + 14 * 4), %eax
+	movw $3, %cx
+	jmp .ext2_data_block_index_indirect
+
+	# eax := current block
+	# ebx := index
+	# cx  := depth
+ .ext2_data_block_index_indirect:
+	call ext2_read_block
+
+	# store depth and index
+	pushw %cx
+	pushl %ebx
+
+	cmpw $1, %cx
+	jbe .ext2_data_block_index_no_shift
+
+	# cl := shift
+	movb $(EXT2_BLOCK_SHIFT - 2), %al
+	decb %cl
+	mulb %cl
+	movb %al, %cl
+
+	# ebx := ebx >> cl
+	shrl %cl, %ebx
+
+ .ext2_data_block_index_no_shift:
+	# edx := index of next block
+	movl %ebx, %eax
+	xorl %edx, %edx
+	movl $(EXT2_BLOCK_SIZE / 4), %ebx
+	divl %ebx
+
+	# eax := next block
+	movl $ext2_block_buffer, %esi
+	movl (%esi, %edx, 4), %eax
+
+	# restore depth and index
+	popl %ebx
+	popw %cx
+
+	loop .ext2_data_block_index_indirect
+
 	jmp .ext2_data_block_index_done
 
  .ext2_data_block_index_out_of_bounds:
@@ -275,14 +352,112 @@ ext2_data_block_index:
 	movl $0, %eax
 	jmp .ext2_data_block_index_done
 
- .ext2_data_block_index_unsupported:
-	movw $ext2_data_block_index_unsupported_msg, %si
+ .ext2_data_block_index_invalid:
+	movw $ext2_data_block_index_invalid_msg, %si
 	call puts; call print_newline
 	movl $0, %eax
 	jmp .ext2_data_block_index_done
 
  .ext2_data_block_index_done:
+	popl %esi
+	popl %edx
 	popl %ecx
+	popl %ebx
+	ret
+
+
+# read bytes from inode (implements read callback)
+#	eax: first byte
+#	ecx: byte count
+#	edi: buffer
+# returns only on success
+.global ext2_inode_read_bytes
+ext2_inode_read_bytes:
+	pushal
+	pushl %ebp
+	movl %esp, %ebp
+	subl $8, %esp
+
+	# save read info
+	movl %eax, 0(%esp)
+	movl %ecx, 4(%esp)
+
+	# check if eax % EXT2_BLOCK_SIZE != 0,
+	# then we need to read a partial block starting from an offset
+	xorl %edx, %edx
+	movl $EXT2_BLOCK_SIZE, %ebx
+	divl %ebx
+	testl %edx, %edx
+	jz .ext2_inode_read_bytes_no_partial_start
+
+	# get data block index and read block
+	call ext2_data_block_index
+	call ext2_read_block
+
+	# ecx := byte count (min(block_size - edx, remaining_bytes))
+	movl $EXT2_BLOCK_SIZE, %ecx
+	subl %edx, %ecx
+	cmpl %ecx, 4(%esp)
+	cmovbl 4(%esp), %ecx
+
+	# update remaining read info
+	addl %ecx, 0(%esp)
+	subl %ecx, 4(%esp)
+
+	# esi := start sector data (block_buffer + index * SECTOR_SIZE)
+	movl $ext2_block_buffer, %esi
+	addl %edx, %esi
+
+	# very dumb memcpy with 32 bit addresses
+	movl $0, %ebx
+ .ext2_inode_read_bytes_memcpy_partial:
+	movb (%esi, %ebx), %al
+	movb %al, (%edi, %ebx)
+	incl %ebx
+	decl %ecx
+	jnz .ext2_inode_read_bytes_memcpy_partial
+	addl %ebx, %edi
+
+	# check if all sectors are read
+	cmpl $0, 4(%esp)
+	je .ext2_inode_read_bytes_done
+
+ .ext2_inode_read_bytes_no_partial_start:
+	# eax := data block index (byte_start / block_size)
+	movl 0(%esp), %eax
+	shrl $(EXT2_BLOCK_SHIFT), %eax
+
+	# get data block index and read block
+	call ext2_data_block_index
+	call ext2_read_block
+
+	# calculate bytes to copy (min(block_size, remaining_bytes))
+	movl $EXT2_BLOCK_SIZE, %ecx
+	cmpl %ecx, 4(%esp)
+	cmovbl 4(%esp), %ecx
+
+	# update remaining read info
+	addl %ecx, 0(%esp)
+	subl %ecx, 4(%esp)
+
+	# very dumb memcpy with 32 bit addresses
+	movl $ext2_block_buffer, %esi
+	movl $0, %ebx
+ .ext2_inode_read_bytes_memcpy:
+	movb (%esi, %ebx), %al
+	movb %al, (%edi, %ebx)
+	incl %ebx
+	decl %ecx
+	jnz .ext2_inode_read_bytes_memcpy
+	addl %ebx, %edi
+
+	# read next block if more sectors remaining
+	cmpl $0, 4(%esp)
+	jnz .ext2_inode_read_bytes_no_partial_start
+
+ .ext2_inode_read_bytes_done:
+	leavel
+	popal
 	ret
 
 
@@ -332,7 +507,7 @@ ext2_directory_find_inode:
 
 	# read current block
 	call ext2_read_block
-	
+
 	# dx := current entry pointer
 	movw $ext2_block_buffer, %si
 
@@ -393,8 +568,14 @@ ext2_directory_find_inode:
 
 
 # search for kernel file from filesystem
+# returns only on success
 .global ext2_find_kernel
 ext2_find_kernel:
+	pushl %eax
+	pushw %cx
+	pushw %di
+	pushw %si
+
 	movl $EXT2_ROOT_INO, %eax
 	call ext2_read_inode
 
@@ -422,7 +603,7 @@ ext2_find_kernel:
 	call puts
 	popw %si
 	call puts; call print_newline
-	
+
 	# search current directory for this file
 	call ext2_directory_find_inode
 	testl %eax, %eax
@@ -443,8 +624,10 @@ ext2_find_kernel:
 	movw $ext2_kernel_found_msg, %si
 	call puts; call print_newline
 
-	1: jmp 1b
-
+	popw %si
+	popw %di
+	popw %cx
+	popl %eax
 	ret
 
  .ext2_find_kernel_part_not_dir:
@@ -490,8 +673,8 @@ ext2_kernel_found_msg:
 
 ext2_data_block_index_out_of_bounds_msg:
 	.asciz "data block index out of bounds"
-ext2_data_block_index_unsupported_msg:
-	.asciz "unsupported data block index"
+ext2_data_block_index_invalid_msg:
+	.asciz "data block index is invalid"
 
 ext2_looking_for_msg:
 	.asciz "looking for "

bootloader/framebuffer.S

@@ -0,0 +1,156 @@
+.set TARGET_WIDTH,	800
+.set TARGET_HEIGHT,	600
+.set TARGET_BPP,	32
+
+.code16
+.section .stage2
+
+# Find suitable video mode
+# return:
+#	ax: video mode number if found, 0 otherwise
+.global vesa_find_video_mode
+vesa_find_video_mode:
+	pushw %ax
+	pushw %cx
+	pushw %di
+	pushl %esi
+
+	# clear target mode and frame buffer
+	movw $0, (vesa_target_mode)
+	movl $0, (framebuffer + 0)
+	movl $0, (framebuffer + 4)
+	movl $0, (framebuffer + 8)
+	movl $0, (framebuffer + 12)
+	movw $0, (framebuffer + 16)
+
+	# get vesa information
+	movw $0x4F00, %ax
+	movw $vesa_info_buffer, %di
+	int $0x10
+	cmpb $0x4F, %al; jne .vesa_unsupported
+	cmpb $0x00, %ah; jne .vesa_error
+
+	# confirm that response starts with 'VESA'
+	cmpl $0x41534556, (vesa_info_buffer)
+	jne .vesa_error
+
+	# confirm that version is atleast 2.0
+	cmpw $0x0200, (vesa_info_buffer + 0x04)
+	jb .vesa_unsupported_version
+
+	movl $(vesa_info_buffer + 0x0E), %esi
+	movl (%esi), %esi
+ .vesa_find_video_mode_loop_modes:
+	cmpw $0xFFFF, (%esi)
+	je .vesa_find_video_mode_loop_modes_done
+
+	# get info of next mode
+	movw $0x4F01, %ax
+	movw (%esi), %cx
+	movw $vesa_mode_info_buffer, %di
+	int $0x10
+	cmpb $0x4F, %al; jne .vesa_unsupported
+	cmpb $0x00, %ah; jne .vesa_error
+
+	# check whether in graphics mode
+	testb $0x10, (vesa_mode_info_buffer + 0)
+	jz .vesa_find_video_mode_next_mode
+
+	# compare mode's dimensions
+	cmpw $TARGET_WIDTH, (vesa_mode_info_buffer + 0x12)
+	jne .vesa_find_video_mode_next_mode
+	cmpw $TARGET_HEIGHT, (vesa_mode_info_buffer + 0x14)
+	jne .vesa_find_video_mode_next_mode
+	cmpb $TARGET_BPP, (vesa_mode_info_buffer + 0x19)
+	jne .vesa_find_video_mode_next_mode
+
+	movl (vesa_mode_info_buffer + 0x28), %esi
+	movl %esi,				(framebuffer + 0)
+	movw (vesa_mode_info_buffer + 0x10), %ax
+	movw %ax,				(framebuffer + 4)
+	movl $TARGET_WIDTH,		(framebuffer + 8)
+	movl $TARGET_HEIGHT,	(framebuffer + 12)
+	movb $TARGET_BPP,		(framebuffer + 16)
+	movb $1,				(framebuffer + 17)
+
+	movw %cx, (vesa_target_mode)
+	jmp .vesa_find_video_mode_loop_modes_done
+
+ .vesa_find_video_mode_next_mode:
+	addl $2, %esi
+	jmp .vesa_find_video_mode_loop_modes
+
+ .vesa_find_video_mode_loop_modes_done:
+	popl %esi
+	popw %di
+	popw %cx
+	popw %ax
+	ret
+
+ .vesa_unsupported:
+	movw $vesa_unsupported_msg, %si
+	jmp print_and_halt
+ .vesa_unsupported_version:
+	movw $vesa_unsupported_version_msg, %si
+	jmp print_and_halt
+ .vesa_error:
+	movw $vesa_error_msg, %si
+	jmp print_and_halt
+
+
+# set mode found from vesa_find_video_mode. if no mode
+# was found, set it to 80x25 text mode to clear the screen.
+.global vesa_set_target_mode
+vesa_set_target_mode:
+	pushw %ax
+	pushw %bx
+
+	movw (vesa_target_mode), %bx
+	testw %bx, %bx
+	jz .vesa_set_target_mode_generic	
+
+	movw $0x4F02, %ax
+	orw $0x4000, %bx
+	int $0x10
+
+	jmp .set_video_done
+
+ .vesa_set_target_mode_generic:
+	movb $0x03, %al
+	movb $0x00, %ah
+	int $0x10
+
+ .set_video_done:
+	popw %bx
+	popw %ax
+	ret
+
+
+vesa_error_msg:
+	.asciz "VESA error"
+vesa_unsupported_msg:
+	.asciz "VESA unsupported"
+vesa_unsupported_version_msg:
+	.asciz "VESA unsupported version"
+vesa_success_msg:
+	.asciz "VESA success"
+
+.section .bss
+
+vesa_info_buffer:
+	.skip 512
+
+vesa_mode_info_buffer:
+	.skip 256
+
+vesa_target_mode:
+	.skip 2
+
+.global framebuffer
+framebuffer:
+	.skip 4	# address
+	.skip 4	# pitch
+	.skip 4	# width
+	.skip 4 # height
+	.skip 1 # bpp
+	.skip 1 # type

bootloader/memory_map.S

@@ -122,6 +122,8 @@ memory_map_error_msg:
 
 .section .bss
 
+.global memory_map
+memory_map:
 memory_map_entry_count:
 	.skip 4
 # 100 entries should be enough...

bootloader/utils.S

@@ -196,6 +196,68 @@ print_number:
 	popa
 	ret
 
+# prints 8 bit hexadecimal number to screen
+#	al:		number to print
+.global print_hex8
+print_hex8:
+	pushw %ax
+	pushw %bx
+	pushw %cx
+
+	movw $16, %bx
+	movw $2,  %cx
+	andw $0xFF, %ax
+	call print_number
+
+	popw %cx
+	popw %bx
+	popw %ax
+	ret
+
+# prints 16 bit hexadecimal number to screen
+#	ax:		number to print
+.global print_hex16
+print_hex16:
+	pushw %bx
+	pushw %cx
+
+	movw $16, %bx
+	movw $4,  %cx
+	call print_number
+
+	popw %cx
+	popw %bx
+	ret
+
+# prints 32 bit hexadecimal number to screen
+#	eax:	number to print
+.global print_hex32
+print_hex32:
+	pushl %eax
+	pushw %dx
+
+	movw %ax, %dx
+
+	shrl $16, %eax;
+	call print_hex16
+
+	movw %dx, %ax
+	call print_hex16
+
+	popw %dx
+	popl %eax
+	ret
+
+# prints 64 bit hexadecimal number to screen
+#	edx:eax:	number to print
+.global print_hex64
+print_hex64:
+	xchgl %eax, %edx
+	call print_hex32
+	xchgl %eax, %edx
+	call print_hex32
+	ret
+
 # test if character is printable ascii
 #	al: character to test
 # return:

kernel/CMakeLists.txt

@@ -12,6 +12,7 @@ set(KERNEL_SOURCES
 	font/prefs.psf.o
 	kernel/ACPI.cpp
 	kernel/APIC.cpp
+	kernel/BootInfo.cpp
 	kernel/CPUID.cpp
 	kernel/Debug.cpp
 	kernel/Device/Device.cpp

kernel/arch/x86_64/PageTable.cpp

@@ -4,7 +4,6 @@
 #include <kernel/LockGuard.h>
 #include <kernel/Memory/kmalloc.h>
 #include <kernel/Memory/PageTable.h>
-#include <kernel/multiboot2.h>
 
 extern uint8_t g_kernel_start[];
 extern uint8_t g_kernel_end[];
@@ -145,6 +144,14 @@ namespace Kernel
 
 		prepare_fast_page();
 
+		// Map main bios area below 1 MiB
+		map_range_at(
+			0x000E0000,
+			P2V(0x000E0000),
+			0x00100000 - 0x000E0000,
+			PageTable::Flags::Present
+		);
+
 		// Map (phys_kernel_start -> phys_kernel_end) to (virt_kernel_start -> virt_kernel_end)
 		ASSERT((vaddr_t)g_kernel_start % PAGE_SIZE == 0);
 		map_range_at(
@@ -169,22 +176,6 @@ namespace Kernel
 			g_userspace_end - g_userspace_start,
 			Flags::Execute | Flags::UserSupervisor | Flags::Present
 		);
-
-		// Map multiboot memory
-		paddr_t multiboot2_data_start = (vaddr_t)g_multiboot2_info & PAGE_ADDR_MASK;
-		paddr_t multiboot2_data_end = (vaddr_t)g_multiboot2_info + g_multiboot2_info->total_size;
-
-		size_t multiboot2_needed_pages = BAN::Math::div_round_up<size_t>(multiboot2_data_end - multiboot2_data_start, PAGE_SIZE);
-		vaddr_t multiboot2_vaddr = reserve_free_contiguous_pages(multiboot2_needed_pages, KERNEL_OFFSET);
-
-		map_range_at(
-			multiboot2_data_start,
-			multiboot2_vaddr,
-			multiboot2_needed_pages * PAGE_SIZE,
-			Flags::ReadWrite | Flags::Present
-		);
-
-		g_multiboot2_info = (multiboot2_info_t*)(multiboot2_vaddr + ((vaddr_t)g_multiboot2_info % PAGE_SIZE));
 	}
 
 	void PageTable::prepare_fast_page()
@@ -371,7 +362,7 @@ namespace Kernel
 	{
 		ASSERT(vaddr);
 		ASSERT(vaddr != fast_page());
-		if (vaddr >= KERNEL_OFFSET)
+		if (vaddr >= KERNEL_OFFSET && s_current)
 			ASSERT_GTE(vaddr, (vaddr_t)g_kernel_start);
 		if ((vaddr >= KERNEL_OFFSET) != (this == s_kernel))
 			Kernel::panic("mapping {8H} to {8H}, kernel: {}", paddr, vaddr, this == s_kernel);

kernel/arch/x86_64/boot.S

@@ -21,8 +21,8 @@ multiboot2_start:
 	.short 5
 	.short 0
 	.long 20
-	.long 1920
-	.long 1080
+	.long 800
+	.long 600
 	.long 32
 
 	# legacy start
@@ -50,11 +50,9 @@ multiboot2_end:
 	g_kernel_cmdline:
 		.skip 4096
 
-	.global g_multiboot2_info
-	g_multiboot2_info:
+	bootloader_magic:
 		.skip 8
-	.global g_multiboot2_magic
-	g_multiboot2_magic:
+	bootloader_info:
 		.skip 8
 
 .section .data
@@ -167,8 +165,8 @@ initialize_paging:
 _start:
 	# Initialize stack and multiboot info
 	movl $V2P(g_boot_stack_top), %esp
-	movl %eax, V2P(g_multiboot2_magic)
-	movl %ebx, V2P(g_multiboot2_info)
+	movl %eax, V2P(bootloader_magic)
+	movl %ebx, V2P(bootloader_info)
 
 	call check_requirements
 	call enable_sse
@@ -200,8 +198,11 @@ higher_half:
 	# call global constuctors
 	call _init
 
-	# call to the kernel itself (clear ebp for stacktrace)
+	# call to the kernel itself (clear rbp for stacktrace)
 	xorq %rbp, %rbp
+
+	movl V2P(bootloader_magic), %edi
+	movl V2P(bootloader_info),  %esi
 	call kernel_main
 
 	# call global destructors

kernel/include/kernel/BananBootloader.h

@@ -0,0 +1,36 @@
+#pragma once
+
+#include <stdint.h>
+
+#define BANAN_BOOTLOADER_MAGIC	0xD3C60CFF
+#define BANAN_BOOTLOADER_FB_RGB	1
+
+struct BananBootFramebufferInfo
+{
+	uint32_t	address;
+	uint32_t	pitch;
+	uint32_t	width;
+	uint32_t	height;
+	uint8_t		bpp;
+	uint8_t		type;
+};
+
+struct BananBootloaderMemoryMapEntry
+{
+	uint64_t address;
+	uint64_t length;
+	uint32_t type;
+} __attribute__((packed));
+
+struct BananBootloaderMemoryMapInfo
+{
+	uint32_t						entry_count;
+	BananBootloaderMemoryMapEntry	entries[];
+} __attribute__((packed));
+
+struct BananBootloaderInfo
+{
+	uint32_t command_line_addr;
+	uint32_t framebuffer_addr;
+	uint32_t memory_map_addr;
+} __attribute__((packed));

kernel/include/kernel/BootInfo.h

@@ -0,0 +1,47 @@
+#pragma once
+
+#include <BAN/String.h>
+#include <BAN/StringView.h>
+#include <BAN/Vector.h>
+
+namespace Kernel
+{
+
+	enum class FramebufferType
+	{
+		NONE,
+		UNKNOWN,
+		RGB
+	};
+
+	struct FramebufferInfo
+	{
+		paddr_t			address;
+		uint32_t		pitch;
+		uint32_t		width;
+		uint32_t		height;
+		uint8_t			bpp;
+		FramebufferType type = FramebufferType::NONE;
+	};
+
+	struct MemoryMapEntry
+	{
+		uint32_t	type;
+		paddr_t		address;
+		uint64_t	length;
+	};
+
+	struct BootInfo
+	{
+		BAN::String					command_line;
+		FramebufferInfo				framebuffer;
+		BAN::Vector<MemoryMapEntry>	memory_map_entries;
+	};
+
+	bool validate_boot_magic(uint32_t magic);
+	void parse_boot_info(uint32_t magic, uint32_t info);
+	BAN::StringView get_early_boot_command_line(uint32_t magic, uint32_t info);
+
+	extern BootInfo g_boot_info;
+
+}

kernel/include/kernel/multiboot2.h

@@ -13,11 +13,18 @@
 
 #define MULTIBOOT2_FRAMEBUFFER_TYPE_RGB	1
 
+#define MULTIBOOT2_MAGIC 0x36d76289
+
 struct multiboot2_tag_t
 {
 	uint32_t type;
 	uint32_t size;
-	multiboot2_tag_t* next() { return (multiboot2_tag_t*)((uintptr_t)this + ((size + 7) & ~7)); }
+	const multiboot2_tag_t* next() const
+	{
+		return reinterpret_cast<const multiboot2_tag_t*>(
+			reinterpret_cast<uintptr_t>(this) + ((size + 7) & ~7)
+		);
+	}
 } __attribute__((packed));
 
 struct multiboot2_cmdline_tag_t : public multiboot2_tag_t
@@ -62,14 +69,3 @@ struct multiboot2_info_t
 	uint32_t reserved;
 	multiboot2_tag_t tags[];
 } __attribute__((packed));
-
-extern "C" multiboot2_info_t* g_multiboot2_info;
-extern "C" uint32_t g_multiboot2_magic;
-
-inline multiboot2_tag_t* multiboot2_find_tag(uint32_t type)
-{
-	for (auto* tag = g_multiboot2_info->tags; tag->type != MULTIBOOT2_TAG_END; tag = tag->next())
-		if (tag->type == type)
-			return tag;
-	return nullptr;
-}

kernel/kernel/ACPI.cpp

@@ -2,7 +2,6 @@
 #include <BAN/StringView.h>
 #include <kernel/ACPI.h>
 #include <kernel/Memory/PageTable.h>
-#include <kernel/multiboot2.h>
 
 #include <lai/core.h>
 
@@ -85,11 +84,14 @@ namespace Kernel
 
 	static const RSDP* locate_rsdp()
 	{
+		// FIXME: add this back
+#if 0
 		// Check the multiboot headers
 		if (auto* rsdp_new = (multiboot2_rsdp_tag_t*)multiboot2_find_tag(MULTIBOOT2_TAG_NEW_RSDP))
 			return (const RSDP*)rsdp_new->data;
 		if (auto* rsdp_old = (multiboot2_rsdp_tag_t*)multiboot2_find_tag(MULTIBOOT2_TAG_OLD_RSDP))
 			return (const RSDP*)rsdp_old->data;
+#endif
 
 		// Look in main BIOS area below 1 MB
 		for (uintptr_t addr = P2V(0x000E0000); addr < P2V(0x000FFFFF); addr += 16)

kernel/kernel/BootInfo.cpp

@@ -0,0 +1,135 @@
+#include <kernel/BootInfo.h>
+#include <kernel/BananBootloader.h>
+#include <kernel/multiboot2.h>
+
+namespace Kernel
+{
+
+	BootInfo g_boot_info;
+
+	void parse_boot_info_multiboot2(uint32_t info)
+	{
+		const auto& multiboot2_info = *reinterpret_cast<const multiboot2_info_t*>(info);
+
+		for (const auto* tag = multiboot2_info.tags; tag->type != MULTIBOOT2_TAG_END; tag = tag->next())
+		{
+			if (tag->type == MULTIBOOT2_TAG_CMDLINE)
+			{
+				const auto& command_line_tag = *reinterpret_cast<const multiboot2_cmdline_tag_t*>(tag);
+				MUST(g_boot_info.command_line.append(command_line_tag.cmdline));
+			}
+			else if (tag->type == MULTIBOOT2_TAG_FRAMEBUFFER)
+			{
+				const auto& framebuffer_tag = *reinterpret_cast<const multiboot2_framebuffer_tag_t*>(tag);
+				g_boot_info.framebuffer.address	= framebuffer_tag.framebuffer_addr;
+				g_boot_info.framebuffer.pitch	= framebuffer_tag.framebuffer_pitch;
+				g_boot_info.framebuffer.width	= framebuffer_tag.framebuffer_width;
+				g_boot_info.framebuffer.height	= framebuffer_tag.framebuffer_height;
+				g_boot_info.framebuffer.bpp		= framebuffer_tag.framebuffer_bpp;
+				if (framebuffer_tag.framebuffer_type == MULTIBOOT2_FRAMEBUFFER_TYPE_RGB)
+					g_boot_info.framebuffer.type = FramebufferType::RGB;
+				else
+					g_boot_info.framebuffer.type = FramebufferType::UNKNOWN;
+			}
+			else if (tag->type == MULTIBOOT2_TAG_MMAP)
+			{
+				const auto& mmap_tag = *reinterpret_cast<const multiboot2_mmap_tag_t*>(tag);
+
+				const size_t entry_count = (mmap_tag.size - sizeof(multiboot2_mmap_tag_t)) / mmap_tag.entry_size;
+				
+				MUST(g_boot_info.memory_map_entries.resize(entry_count));
+
+				for (size_t i = 0; i < entry_count; i++)
+				{
+					const auto& mmap_entry = *reinterpret_cast<const multiboot2_mmap_entry_t*>(reinterpret_cast<uintptr_t>(tag) + sizeof(multiboot2_mmap_tag_t) + i * mmap_tag.entry_size);
+					dprintln("entry {16H} {16H} {8H}",
+						(uint64_t)mmap_entry.base_addr,
+						(uint64_t)mmap_entry.length,
+						(uint64_t)mmap_entry.type
+					);
+					g_boot_info.memory_map_entries[i].address	= mmap_entry.base_addr;
+					g_boot_info.memory_map_entries[i].length	= mmap_entry.length;
+					g_boot_info.memory_map_entries[i].type		= mmap_entry.type;
+				}
+			}
+		}
+	}
+
+	BAN::StringView get_early_boot_command_line_multiboot2(uint32_t info)
+	{
+		const auto& multiboot2_info = *reinterpret_cast<const multiboot2_info_t*>(info);
+		for (const auto* tag = multiboot2_info.tags; tag->type != MULTIBOOT2_TAG_END; tag = tag->next())
+			if (tag->type == MULTIBOOT2_TAG_CMDLINE)
+				return reinterpret_cast<const multiboot2_cmdline_tag_t*>(tag)->cmdline;
+		return {};
+	}
+
+	void parse_boot_info_banan_bootloader(uint32_t info)
+	{
+		const auto& banan_bootloader_info = *reinterpret_cast<const BananBootloaderInfo*>(info);
+
+		const char* command_line = reinterpret_cast<const char*>(banan_bootloader_info.command_line_addr);
+		MUST(g_boot_info.command_line.append(command_line));
+
+		const auto& framebuffer = *reinterpret_cast<BananBootFramebufferInfo*>(banan_bootloader_info.framebuffer_addr);
+		if (framebuffer.type == BANAN_BOOTLOADER_FB_RGB)
+		{
+			g_boot_info.framebuffer.address	= framebuffer.address;
+			g_boot_info.framebuffer.width	= framebuffer.width;
+			g_boot_info.framebuffer.height	= framebuffer.height;
+			g_boot_info.framebuffer.pitch	= framebuffer.pitch;
+			g_boot_info.framebuffer.bpp		= framebuffer.bpp;
+			g_boot_info.framebuffer.type	= FramebufferType::RGB;
+		}
+
+		const auto& memory_map =  *reinterpret_cast<BananBootloaderMemoryMapInfo*>(banan_bootloader_info.memory_map_addr);
+		MUST(g_boot_info.memory_map_entries.resize(memory_map.entry_count));
+		for (size_t i = 0; i < memory_map.entry_count; i++)
+		{
+			const auto& mmap_entry = memory_map.entries[i];
+			g_boot_info.memory_map_entries[i].address	= mmap_entry.address;
+			g_boot_info.memory_map_entries[i].length	= mmap_entry.length;
+			g_boot_info.memory_map_entries[i].type		= mmap_entry.type;
+		}
+	}
+
+	BAN::StringView get_early_boot_command_line_banan_bootloader(uint32_t info)
+	{
+		const auto& banan_bootloader_info = *reinterpret_cast<const BananBootloaderInfo*>(info);
+		return reinterpret_cast<const char*>(banan_bootloader_info.command_line_addr);
+	}
+
+	bool validate_boot_magic(uint32_t magic)
+	{
+		if (magic == MULTIBOOT2_MAGIC)
+			return true;
+		if (magic == BANAN_BOOTLOADER_MAGIC)
+			return true;
+		return false;	
+	}
+
+	void parse_boot_info(uint32_t magic, uint32_t info)
+	{
+		switch (magic)
+		{
+			case MULTIBOOT2_MAGIC:
+				return parse_boot_info_multiboot2(info);
+			case BANAN_BOOTLOADER_MAGIC:
+				return parse_boot_info_banan_bootloader(info);
+		}
+		ASSERT_NOT_REACHED();
+	}
+
+	BAN::StringView get_early_boot_command_line(uint32_t magic, uint32_t info)
+	{
+		switch (magic)
+		{
+			case MULTIBOOT2_MAGIC:
+				return get_early_boot_command_line_multiboot2(info);
+			case BANAN_BOOTLOADER_MAGIC:
+				return get_early_boot_command_line_banan_bootloader(info);
+		}
+		ASSERT_NOT_REACHED();
+	}
+
+}

kernel/kernel/FS/Ext2/Inode.cpp

@@ -56,9 +56,7 @@ namespace Kernel
 
 		const uint32_t indices_per_block = blksize() / sizeof(uint32_t);
 
-		uint32_t divisor = 1;
-		for (uint32_t i = 1; i < depth; i++)
-			divisor *= indices_per_block;
+		const uint32_t divisor = (depth > 1) ? indices_per_block * (depth - 1) : 1;
 
 		const uint32_t next_block = block_buffer.span().as_span<uint32_t>()[(index / divisor) % indices_per_block];
 		if (next_block == 0)

kernel/kernel/Memory/Heap.cpp

@@ -1,7 +1,7 @@
+#include <kernel/BootInfo.h>
 #include <kernel/LockGuard.h>
 #include <kernel/Memory/Heap.h>
 #include <kernel/Memory/PageTable.h>
-#include <kernel/multiboot2.h>
 
 extern uint8_t g_kernel_end[];
 
@@ -26,30 +26,33 @@ namespace Kernel
 
 	void Heap::initialize_impl()
 	{
-		auto* mmap_tag = (multiboot2_mmap_tag_t*)multiboot2_find_tag(MULTIBOOT2_TAG_MMAP);
-		if (mmap_tag == nullptr)
+		if (g_boot_info.memory_map_entries.empty())
 			Kernel::panic("Bootloader did not provide a memory map");
 
-		for (size_t offset = sizeof(*mmap_tag); offset < mmap_tag->size; offset += mmap_tag->entry_size)
+		for (const auto& entry : g_boot_info.memory_map_entries)
 		{
-			auto* mmap_entry = (multiboot2_mmap_entry_t*)((uintptr_t)mmap_tag + offset);
+			dprintln("{16H}, {16H}, {8H}",
+				entry.address,
+				entry.length,
+				entry.type
+			);
 
-			if (mmap_entry->type == 1)
-			{				
-				paddr_t start = mmap_entry->base_addr;
-				if (start < V2P(g_kernel_end))
-					start = V2P(g_kernel_end);
-				if (auto rem = start % PAGE_SIZE)
-					start += PAGE_SIZE - rem;
+			if (entry.type != 1)
+				continue;
+				
+			paddr_t start = entry.address;
+			if (start < V2P(g_kernel_end))
+				start = V2P(g_kernel_end);
+			if (auto rem = start % PAGE_SIZE)
+				start += PAGE_SIZE - rem;
 
-				paddr_t end = mmap_entry->base_addr + mmap_entry->length;
-				if (auto rem = end % PAGE_SIZE)
-					end -= rem;
+			paddr_t end = entry.address + entry.length;
+			if (auto rem = end % PAGE_SIZE)
+				end -= rem;
 
-				// Physical pages needs atleast 2 pages
-				if (end > start + PAGE_SIZE)
-					MUST(m_physical_ranges.emplace_back(start, end - start));
-			}
+			// Physical pages needs atleast 2 pages
+			if (end > start + PAGE_SIZE)
+				MUST(m_physical_ranges.emplace_back(start, end - start));
 		}
 
 		size_t total = 0;

kernel/kernel/Terminal/Serial.cpp

@@ -57,7 +57,11 @@ namespace Kernel
 				auto& driver = s_serial_drivers[i];
 				driver.m_port = s_serial_ports[i];
 				if (!driver.initialize_size())
-					continue;
+				{
+					// if size detection fails, just use some random size
+					driver.m_width	= 999;
+					driver.m_height	= 999;
+				}
 				count++;
 			}
 		}

kernel/kernel/Terminal/VesaTerminalDriver.cpp

@@ -1,42 +1,41 @@
 #include <BAN/Errors.h>
+#include <kernel/BootInfo.h>
 #include <kernel/Debug.h>
 #include <kernel/Memory/PageTable.h>
-#include <kernel/multiboot2.h>
 #include <kernel/Terminal/VesaTerminalDriver.h>
 
 using namespace Kernel;
 
 VesaTerminalDriver* VesaTerminalDriver::create()
 {
-	auto* framebuffer_tag = (multiboot2_framebuffer_tag_t*)multiboot2_find_tag(MULTIBOOT2_TAG_FRAMEBUFFER);
-	if (framebuffer_tag == nullptr)	
+	if (g_boot_info.framebuffer.type == FramebufferType::NONE)	
 	{
 		dprintln("Bootloader did not provide framebuffer");
 		return nullptr;
 	}
 
-	if (framebuffer_tag->framebuffer_type != MULTIBOOT2_FRAMEBUFFER_TYPE_RGB)
+	if (g_boot_info.framebuffer.type != FramebufferType::RGB)
 	{
-		dprintln("unsupported framebuffer type {}", framebuffer_tag->framebuffer_type);
+		dprintln("unsupported framebuffer type");
 		return nullptr;
 	}
 
-	if (framebuffer_tag->framebuffer_bpp != 24 && framebuffer_tag->framebuffer_bpp != 32)
+	if (g_boot_info.framebuffer.bpp != 24 && g_boot_info.framebuffer.bpp != 32)
 	{
-		dprintln("Unsupported bpp {}", framebuffer_tag->framebuffer_bpp);
+		dprintln("Unsupported bpp {}", g_boot_info.framebuffer.bpp);
 		return nullptr;
 	}
 
 	dprintln("Graphics Mode {}x{} ({} bpp)",
-		(uint32_t)framebuffer_tag->framebuffer_width,
-		(uint32_t)framebuffer_tag->framebuffer_height,
-		(uint8_t)framebuffer_tag->framebuffer_bpp
+		g_boot_info.framebuffer.width,
+		g_boot_info.framebuffer.height,
+		g_boot_info.framebuffer.bpp
 	);
 
-	paddr_t paddr = framebuffer_tag->framebuffer_addr & PAGE_ADDR_MASK;
+	paddr_t paddr = g_boot_info.framebuffer.address & PAGE_ADDR_MASK;
 	size_t needed_pages = range_page_count(
-		framebuffer_tag->framebuffer_addr,
-		framebuffer_tag->framebuffer_pitch * framebuffer_tag->framebuffer_height
+		g_boot_info.framebuffer.address,
+		g_boot_info.framebuffer.pitch * g_boot_info.framebuffer.height
 	);
 
 	vaddr_t vaddr = PageTable::kernel().reserve_free_contiguous_pages(needed_pages, KERNEL_OFFSET);
@@ -45,10 +44,10 @@ VesaTerminalDriver* VesaTerminalDriver::create()
 	PageTable::kernel().map_range_at(paddr, vaddr, needed_pages * PAGE_SIZE, PageTable::Flags::UserSupervisor | PageTable::Flags::ReadWrite | PageTable::Flags::Present);
 
 	auto* driver = new VesaTerminalDriver(
-		framebuffer_tag->framebuffer_width,
-		framebuffer_tag->framebuffer_height,
-		framebuffer_tag->framebuffer_pitch,
-		framebuffer_tag->framebuffer_bpp,
+		g_boot_info.framebuffer.width,
+		g_boot_info.framebuffer.height,
+		g_boot_info.framebuffer.pitch,
+		g_boot_info.framebuffer.bpp,
 		vaddr
 	);
 	driver->set_cursor_position(0, 0);

kernel/kernel/kernel.cpp

@@ -1,5 +1,6 @@
 #include <kernel/ACPI.h>
 #include <kernel/Arch.h>
+#include <kernel/BootInfo.h>
 #include <kernel/Debug.h>
 #include <kernel/FS/DevFS/FileSystem.h>
 #include <kernel/FS/ProcFS/FileSystem.h>
@@ -12,7 +13,6 @@
 #include <kernel/Memory/Heap.h>
 #include <kernel/Memory/kmalloc.h>
 #include <kernel/Memory/PageTable.h>
-#include <kernel/multiboot2.h>
 #include <kernel/PCI.h>
 #include <kernel/PIC.h>
 #include <kernel/Process.h>
@@ -31,13 +31,9 @@ struct ParsedCommandLine
 	BAN::StringView root;
 };
 
-static bool should_disable_serial()
+static bool should_disable_serial(BAN::StringView full_command_line)
 {
-	auto* cmdline_tag = (multiboot2_cmdline_tag_t*)multiboot2_find_tag(MULTIBOOT2_TAG_CMDLINE);
-	if (cmdline_tag == nullptr)
-		return false;
-
-	const char* start = cmdline_tag->cmdline;
+	const char* start = full_command_line.data();
 	const char* current = start;
 	while (true)
 	{
@@ -59,13 +55,8 @@ static ParsedCommandLine cmdline;
 
 static void parse_command_line()
 {
-	auto* cmdline_tag = (multiboot2_cmdline_tag_t*)multiboot2_find_tag(MULTIBOOT2_TAG_CMDLINE);
-	if (cmdline_tag == nullptr)
-		return;
-
-	BAN::StringView full_command_line(cmdline_tag->cmdline);
+	auto full_command_line = Kernel::g_boot_info.command_line.sv();
 	auto arguments = MUST(full_command_line.split(' '));
-
 	for (auto argument : arguments)
 	{
 		if (argument == "noapic")
@@ -83,27 +74,31 @@ TerminalDriver* g_terminal_driver = nullptr;
 
 static void init2(void*);
 
-extern "C" void kernel_main()
+extern "C" void kernel_main(uint32_t boot_magic, uint32_t boot_info)
 {
 	using namespace Kernel;
 
 	DISABLE_INTERRUPTS();
 
-	if (!should_disable_serial())
+	if (!validate_boot_magic(boot_magic))
+	{
+		Serial::initialize();
+		dprintln("Unrecognized boot magic {8H}", boot_magic);
+		return;
+	}
+
+	if (!should_disable_serial(get_early_boot_command_line(boot_magic, boot_info)))
 	{
 		Serial::initialize();
 		dprintln("Serial output initialized");
 	}
 
-	if (g_multiboot2_magic != 0x36d76289)
-	{
-		dprintln("Invalid multiboot magic number");
-		return;
-	}
-
 	kmalloc_initialize();
 	dprintln("kmalloc initialized");
 
+	parse_boot_info(boot_magic, boot_info);
+	dprintln("boot info parsed");
+
 	GDT::initialize();
 	dprintln("GDT initialized");