Imbus/xv6-riscv-kernel
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separate source into kernel/ user/ mkfs/

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This commit is contained in:
Robert Morris 2019-06-11 09:57:14 -04:00
parent 91ba81110a
commit 5753553213
72 changed files with 157 additions and 296 deletions
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kernel/start.c Normal file
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#include "types.h"
#include "param.h"
#include "memlayout.h"
#include "riscv.h"
#include "defs.h"
void main();
// entry.S needs one stack per CPU.
__attribute__ ((aligned (16))) char stack0[4096 * NCPU];
// scratch area for timer interrupt, one per CPU.
uint64 mscratch0[NCPU * 32];
// assembly code in kernelvec for machine-mode timer interrupt.
extern void machinevec();
// entry.S jumps here in machine mode on stack0.
void
mstart()
{
// set M Previous Privilege mode to Supervisor, for mret.
unsigned long x = r_mstatus();
x &= ~MSTATUS_MPP_MASK;
x |= MSTATUS_MPP_S;
w_mstatus(x);
// set M Exception Program Counter to main, for mret.
// requires gcc -mcmodel=medany
w_mepc((uint64)main);
// disable paging for now.
w_satp(0);
// delegate all interrupts and exceptions to supervisor mode.
w_medeleg(0xffff);
w_mideleg(0xffff);
// set up to receive timer interrupts in machine mode,
// for pre-emptive switching and (on hart 0) to drive time.
int id = r_mhartid();
uint64 *scratch = &mscratch0[32 * id];
*(uint64*)CLINT_MTIMECMP(id) = *(uint64*)CLINT_MTIME + 10000;
scratch[4] = CLINT_MTIMECMP(id);
scratch[5] = 10000000;
w_mscratch((uint64)scratch);
w_mtvec((uint64)machinevec);
w_mstatus(r_mstatus() | MSTATUS_MIE);
w_mie(r_mie() | MIE_MTIE);
// keep each CPU's hartid in its tp register, for cpuid().
w_tp(id);
// call main() in supervisor mode.
asm volatile("mret");
}