Fábio Coutada
173b2c3330
- Add kernel/arch/arm/boot.S with ARMv7 assembly entry, stack setup, BSS clear - Add kernel/arch/arm/linker.ld for QEMU virt memory layout (load at 0x40000000) - Add kernel/arch/arm/uart.c/uart.h for PL011 serial output - Add kernel/kernel.c with kernel_main() idle loop - Add kernel/Makefile for arm-none-eabi-gcc cross-compile and QEMU launch - Add kernel/README.md with build/run instructions - Ignore kernel build artifacts in .gitignore
34 lines
700 B
ArmAsm
34 lines
700 B
ArmAsm
/*
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* Universalisos ARMv7 boot code for QEMU virt machine.
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*
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* This is the first code executed after QEMU loads the kernel image.
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* It sets up the stack, zeroes the BSS, and jumps to kernel_main().
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*/
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.syntax unified
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.arch armv7-a
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.section .text.boot
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.global _start
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_start:
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/* Disable interrupts until the kernel is ready. */
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cpsid if
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/* Set up the stack at the top of the reserved boot region. */
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ldr sp, =_stack_top
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/* Clear the BSS section. */
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ldr r0, =_bss_start
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ldr r1, =_bss_end
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mov r2, #0
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1:
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cmp r0, r1
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bge 2f
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str r2, [r0], #4
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b 1b
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2:
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/* Enter the C kernel. */
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bl kernel_main
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/* Halt if kernel_main ever returns. */
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b .
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