main.c

#include "types.h"
#include "defs.h"
#include "param.h"
#include "memlayout.h"
#include "mmu.h"
#include "proc.h"
#include "mist32.h"

static void startothers(void);
static void mpmain(void)  __attribute__((noreturn));
extern pde_t *kpgdir;
extern char end[]; // first address after kernel loaded from ELF file

// Bootstrap processor starts running C code here.
// Allocate a real stack and switch to it, first
// doing some setup required for memory allocator to work.
int
main(void)
{
  kinit1(end, P2V(4*1024*1024)); // phys page allocator
  kvmalloc();      // kernel page table
  mpinit();        // collect info about this machine
  lapicinit();
  seginit();       // set up segments
  cprintf("\ncpu%d: starting xv6\n\n", cpu()->id);
  /* picinit();       // interrupt controller */
  /* ioapicinit();    // another interrupt controller */
  gciinit();       // I/O bus init
  consoleinit();   // I/O devices & their interrupts
  uartinit();      // serial port
  pinit();         // process table
  tvinit();        // trap vectors
  binit();         // buffer cache
  fileinit();      // file table
  iinit();         // inode cache
  ideinit();       // disk
  if(!ismp)
    timerinit();   // uniprocessor timer
  startothers();   // start other processors
  kinit2(P2V(4*1024*1024), P2V(PHYSTOP)); // must come after startothers()
  userinit();      // first user process
  // Finish setting up this processor in mpmain.
  mpmain();
}

// Common CPU setup code.
static void
mpmain(void)
{
  cprintf("cpu%d: starting\n", cpu()->id);
  idtinit();       // load idt register
  /* xchg(&cpu->started, 1); // tell startothers() we're up */
  cpu()->started = 1; // tell startothers() we're up
  scheduler();     // start running processes
}

pde_t entrypgdir[];  // For entry.S

// Start the non-boot (AP) processors.
static void
startothers(void)
{
  /* mist32 is not supported multiprocessor */
}

// Boot page table used in entry.S and entryother.S.
// Page directories (and page tables), must start on a page boundary,
// hence the "__aligned__" attribute.  
// Use PTE_PS in page directory entry to enable 4Mbyte pages.
__attribute__((__aligned__(PGSIZE)))
pde_t entrypgdir[NPDENTRIES] = {
  // Map VA's [0, 4MB) to PA's [0, 4MB)
  [0] = (0) | PTE_V | PTE_PP_RWXX | PTE_EX | PTE_PE,
  // Map VA's [KERNBASE, KERNBASE+4MB) to PA's [0, 4MB)
  [KERNBASE>>PDXSHIFT] = (0) | PTE_V | PTE_PP_RWXX | PTE_EX | PTE_PE,
};

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// Blank page.