接續昨天的題目

原本今天打算寫完這題的，但一直卡在一個地方，

就先貼出我寫到一半的成果吧

// kernel/sysproc.c
uint64
sys_sysinfo(void)
{
  uint64 info;
  struct sysinfo kinfo;
  struct proc *p = myproc();

  if(argaddr(0, &info) < 0)
    return -1;

  kinfo.freemem = freemem();
  kinfo.nproc = nproc();

  if(copyout(p->pagetable, info, (char *)&kinfo, sizeof(info)) < 0)
    return -1;
  
  return 0;
}

// kernel/kalloc.c
uint64
freemem(void)
{
  uint64 npage = 0;
  struct run *r;
  r = kmem.freelist;

  while (r) {
    npage++;
    r = r->next;
  }
  
  return npage * PGSIZE;
}