8c44d12357
Boots under QEMU on all three ISAs from one clang build: - shared C core (kmain, console) calls a small per-arch contract (arch.h) - per-arch asm entry + trap/vector table + UART driver - parallel Makefile (make -j), 'make run-<arch>', 'make sizes' M1 = boot, UART up, trap vector installed, banner from kmain().
28 lines
647 B
ArmAsm
28 lines
647 B
ArmAsm
# boot.S (RISC-V rv64) — the minimal asm entry.
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# QEMU 'virt' with -bios none enters here at 0x80000000 in M-mode,
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# all harts. We park every hart but hart 0, set a stack, clear .bss,
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# and jump to kmain(). This is the irreducible asm part for this arch.
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.section .text.boot
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.globl _start
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_start:
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# Only hart 0 continues; others wait forever (WFI loop).
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csrr t0, mhartid
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bnez t0, park
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# Set up the stack (defined in the linker script).
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la sp, _stack_top
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# Zero the .bss section: [__bss_start, __bss_end).
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la t0, __bss_start
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la t1, __bss_end
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1: bgeu t0, t1, 2f
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sd zero, (t0)
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addi t0, t0, 8
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j 1b
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2:
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call kmain
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park:
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wfi
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j park
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