// TODO: CHECK/REPLACE/UPDATE OLD CODE (this file is based on xv6)
        // qemu -kernel loads the kernel at 0x80000000
        // and causes each hart (i.e. CPU) to jump there.
        // kernel.ld causes the following code to
        // be placed at 0x80000000.

.option norvc
.section .text
.global _entry
_entry:
        // set up a stack for C.
        // stack0 is declared in start.c,
        // with a 4096-byte stack per CPU.
        // sp = stack0 + (hartid * 4096)
        la sp, stack0
        li a0, 1024*4
        csrr a1, mhartid
        addi a1, a1, 1
        mul a0, a0, a1
        add sp, sp, a0
        // jump to start() in start.c
        call start
spin:
        j spin