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29 lines
1.0 KiB
29 lines
1.0 KiB
2 years ago
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#
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# _mentry is the entry point of riscv-pke OS kernel.
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#
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# !Important (for your understanding)
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# Before entering _mentry, two argument registers, i.e., a0(x10) and a1(x11), are set by
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# our emulator (i.e., spike).
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# [a0] = processor ID (in the context of RISC-V, a processor is called as a HART, i.e.,
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# Hardware Thread).
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# [a1] = pointer to the DTS (i.e., Device Tree String), which is stored in the memory of
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# RISC-V guest computer emulated by spike.
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#
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.globl _mentry
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_mentry:
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# [mscratch] = 0; mscratch points the stack bottom of machine mode computer
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csrw mscratch, x0
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# following codes allocate a 4096-byte stack for each HART, although we use only
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# ONE HART in this lab.
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la sp, stack0 # stack0 is statically defined in kernel/machine/minit.c
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li a3, 4096 # 4096-byte stack
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csrr a4, mhartid # [mhartid] = core ID
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addi a4, a4, 1
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mul a3, a3, a4
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add sp, sp, a3 # re-arrange the stack points so that they don't overlap
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# jump to mstart(), i.e., machine state start function in kernel/machine/minit.c
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call m_start
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