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Kernel: Print CPU check errors by writing to VRAM

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This commit is contained in:
Tim Schumacher 2021-10-02 05:03:56 +02:00 • committed by Linus Groh
parent c488f5a59d
commit 52621093c7
1 changed files with 22 additions and 19 deletions
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41
Kernel/Prekernel/Arch/x86/boot.S
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@ -120,28 +120,31 @@ print_and_halt:
.equ REAL_MODE_CODE, 0x500 .equ REAL_MODE_CODE, 0x500
.equ PROTECTED_MODE_16_BIT_CODE, 0x600 .equ PROTECTED_MODE_16_BIT_CODE, 0x600
movl %esp, %ebp movl %esp, %ebp
movl 4(%ebp), %edi movl 4(%ebp), %esi
/* Copy string to low memory section */ mov $0xb8000, %ecx /* VRAM address. */
movl %edi, %esi mov $0x07, %ah /* grey-on-black text. */
xor %ecx, %ecx
pushl %eax .print_str_loop:
pushl %edi lodsb /* Loads a byte from address at %esi into %al and increments %esi. */
check_string_length:
movb (%edi), %ah
cmp $0, %ah
je check_string_length_exit
inc %ecx
inc %edi
jmp check_string_length
check_string_length_exit:
popl %edi
popl %eax
/* source address of the code is ESI */ test %al, %al
movw %cx, (COPIED_STRING_LOCATION) jz .print_str_end
mov $COPIED_STRING_LOCATION + 2, %edi /* destination address of the code */
movw %ax, (%ecx)
add $2, %ecx
jmp .print_str_loop
.print_str_end:
/* Calculate string length into %ecx */
mov %esi, %ecx
sub 4(%ebp), %ecx
movw %cx, (COPIED_STRING_LOCATION) /* Store string length for later use. */
/* Copy string into lower memory */
mov 4(%ebp), %esi
mov $COPIED_STRING_LOCATION + 2, %edi
rep movsb rep movsb
/* Copy gdt_table_real_mode to low memory section */ /* Copy gdt_table_real_mode to low memory section */