diff options
Diffstat (limited to 'boot/boot.asm')
| -rw-r--r-- | boot/boot.asm | 49 |
1 files changed, 24 insertions, 25 deletions
diff --git a/boot/boot.asm b/boot/boot.asm index 645061c..d79c9a1 100644 --- a/boot/boot.asm +++ b/boot/boot.asm @@ -2,54 +2,53 @@ ; get a prototype off the ground quickly without pissing around ; Declare constants used for creating a multiboot header. -MBALIGN equ 1<<0 ; align loaded modules on page boundaries -MEMINFO equ 1<<1 ; provide memory map -FLAGS equ MBALIGN | MEMINFO ; this is the Multiboot 'flag' field -MAGIC equ 0x1BADB002 ; 'magic number' lets bootloader find the header -CHECKSUM equ -(MAGIC + FLAGS) ; checksum of above, to prove we are multiboot - -; Declare a header as in the Multiboot Standard. We put this into a special -; section so we can force the header to be in the start of the final program. -; You don't need to understand all these details as it is just magic values that -; is documented in the multiboot standard. The bootloader will search for this -; magic sequence and recognize us as a multiboot kernel. +MBALIGN equ 1<<0 ; align loaded modules on page boundaries +MEMINFO equ 1<<1 ; Ask for memory map +FLAGS equ MBALIGN | MEMINFO +MAGIC equ 0x1BADB002 +CHECKSUM equ -(MAGIC + FLAGS) + +; Standard mutliboot header so GRUB and other bootloaders can boot the kernel section .multiboot align 4 dd MAGIC dd FLAGS dd CHECKSUM -; Currently the stack pointer register (esp) points at anything and using it may -; cause massive harm. Instead, we'll provide our own stack. We will allocate -; room for a small temporary stack by creating a symbol at the bottom of it, -; then allocating 16384 bytes for it, and finally creating a symbol at the top. +; Init our very own 16K stack section .bootstrap_stack align 4 stack_bottom: times 16384 db 0 stack_top: -; The linker script specifies _start as the entry point to the kernel and the -; bootloader will jump to this position once the kernel has been loaded. It -; doesn't make sense to return from this function as the bootloader is gone. section .text global _start +global _kernel_exit + _start: + ; Functions in external objects extern kernel_main - extern console_print - extern console_set_colors + extern console_print_string + extern console_set_color + ; Set stack up ready for C mov esp, stack_top + push eax + push ebx call kernel_main ; Let the user know that kernel_main() exited - push word 0x0007 - call console_set_colors - push mainexit - call console_print + push 0x0A + call console_set_color ; Reset text colour + push exitmain + call console_print_string + + ; Wake us not from our slumber cli +_kernel_exit: .hang: hlt jmp .hang -mainexit db 10,"asm: kernel_main() exited",0 +exitmain db 10,"boot: kernel_main() exited",0
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