diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/boot32.s | 59 |
1 files changed, 19 insertions, 40 deletions
diff --git a/src/boot32.s b/src/boot32.s index e71d047..dc02102 100644 --- a/src/boot32.s +++ b/src/boot32.s @@ -4,7 +4,7 @@ .section .text .code32 -// Entry point. It puts the machine into a consistent state and starts long mode. +/* Entry point. It puts the machine into a consistent state and starts long mode. */ _start: mov $0x80000, %esp // Setup the stack. push %ebx // Pass multiboot info structure. @@ -19,7 +19,6 @@ _start: lgdt (gdtdesc) jmpl $0x8, $long_mode_start - //jmp gdt64.code_segment:long_mode_start call halt halt: @@ -69,44 +68,44 @@ check_long_mode: setup_page_tables: mov $page_table_l3, %eax - or $0b11 , %eax // present, writable + or $0b11 , %eax /* present, writable */ mov %eax, (page_table_l4) mov $page_table_l2, %eax - or $0b11, %eax // present, writable + or $0b11, %eax /* present, writable */ mov %eax, (page_table_l3) - mov $0, %ecx // counter + mov $0, %ecx /* counter */ .loop: - mov $0x200000, %eax // 2MiB + mov $0x200000, %eax /* 2MiB */ mul %ecx - or $0b10000011, %eax // present, writable, huge page + or $0b10000011, %eax /* present, writable, huge page */ mov %eax, +page_table_l2(,%ecx,8) - inc %ecx // increment counter - cmp $512, %ecx // checks if the whole table is mapped - jne .loop // if not, continue + inc %ecx /* increment counter */ + cmp $512, %ecx /* checks if the whole table is mapped */ + jne .loop /* if not, continue */ ret enable_paging: - // pass page table location to cpu + /* pass page table location to cpu */ mov $page_table_l4, %eax mov %eax, %cr3 - // enable PAE + /* enable PAE */ mov %cr4, %eax or $(1 << 5), %eax mov %eax, %cr4 - // enable long mode + /* enable long mode */ mov $0xC0000080, %ecx rdmsr or $(1 << 8), %eax wrmsr - // enable paging + /* enable paging */ mov %cr0, %eax or $(1 << 31), %eax mov %eax, %cr0 @@ -114,7 +113,7 @@ enable_paging: ret error: - // // print "ERR: X" where X is the error code + /* print in VGA "ERR: X" where X is the error code */ movl $0x4f524f45, 0xb8000 movl $0x4f3a4f52, 0xb8004 movl $0x4f204f20, 0xb8008 @@ -134,31 +133,11 @@ stack_bottom: stack_top: .section .rodata -.p2align 2 # force 4 byte alignment +.p2align 2 /* force 4 byte alignment */ gdt64: - .quad 0 // zero entry + .quad 0 /* zero entry */ .code_segment: - .quad (1 << 43) | (1 << 44) | (1 << 47) | (1 << 53) # code segment + .quad (1 << 43) | (1 << 44) | (1 << 47) | (1 << 53) /* code segment */ gdtdesc: - .word (gdtdesc - gdt64 - 1) # sizeof(gdt) - 1 - .long gdt64 # address gdt - -//# Bootstrap GDT -//gdt: -// SEG_NULLASM # null seg -// SEG_ASM(STA_X|STA_R, 0x0, 0xffffffff) # code seg -// SEG_ASM(STA_W, 0x0, 0xffffffff) # data seg -// -//gdtdesc: -// .word (gdtdesc - gdt - 1) # sizeof(gdt) - 1 -// .long gdt # address gdt -// -//section .rodata -//gdt64: -// dq 0 ; zero entry -//.code_segment: equ $ - gdt64 -// dq (1 << 43) | (1 << 44) | (1 << 47) | (1 << 53) ; code segment -//.pointer: -// dw $ - gdt64 - 1 ; length -// dq gdt64 ; address -//
\ No newline at end of file + .word (gdtdesc - gdt64 - 1) /* sizeof(gdt) - 1 */ + .long gdt64 /* address gdt */
\ No newline at end of file |