43 lines
1.1 KiB
ArmAsm
43 lines
1.1 KiB
ArmAsm
; Here is our entry point to the kernel
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; A very simple assembly file
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; We set up some parameters and then pass the execution to our kmain
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global loader ; entry symbol for ELF
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extern _main
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MAGIC_NUMBER equ 0x1BADB002 ; magic number constant
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FLAGS equ 0x3
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CHECKSUM equ -(MAGIC_NUMBER + FLAGS) ; calculate the checksum
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KERNEL_STACK_SIZE equ 4096
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; The multiboot section is a semi requirement for grub
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; All this is doing is placing the required magic number, flags, and the checksum into the file first
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; This lets grub know if this is a valid multiboot kernel or not
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section .multiboot
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align 4 ; code must be 4 byte aligned
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dd MAGIC_NUMBER
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dd FLAGS
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dd CHECKSUM
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; Here we're setting up the stack
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; Giving us 4096 bytes (resb)
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section .bss
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align 4
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kernel_stack:
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resb KERNEL_STACK_SIZE
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section .text
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loader:
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mov esp, kernel_stack + KERNEL_STACK_SIZE ; move the top of the stack into esp
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push eax
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push ebx
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call _main ; pass execution over to our _main function, where all of the real stuff is done
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; Should the system exit, we clear the interrupt flag
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; and do an infinite loop of nothing
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cli
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loop: hlt
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jmp loop
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