date and time created 91/04/28 17:15:43 by william

[unix-history] / usr / src / sys / i386 / stand / bootxx.c

/*-
* Copyright (c) 1990 The Regents of the University of California.
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* William Jolitz.
*
* %sccs.include.redist.c%
*
*      @(#)bootxx.c    7.2 (Berkeley) %G%
*/

#include "param.h"
#include <a.out.h>
#include "saio.h"
#include "reboot.h"
#include "disklabel.h"

char *bootprog = "/boot";
extern int opendev, bootdev, cyloffset;
extern struct disklabel disklabel;

/*
* Boot program... loads /boot out of filesystem indicated by arguements.
* We assume an autoboot unless we detect a misconfiguration.
*/

main(dev, unit, off)
{
       register struct disklabel *lp;
       register int io, partition, howto;


       /* are we a disk, if so look at disklabel and do things */
       lp = &disklabel;
       if (lp->d_magic == DISKMAGIC) {
           /*
            * Synthesize bootdev from dev, unit, type and partition
            * information from the block 0 bootstrap.
            * It's dirty work, but someone's got to do it.
            * This will be used by the filesystem primatives, and
            * drivers. Ultimately, opendev will be created corresponding
            * to which drive to pass to top level bootstrap.
            */
           for (io = 0; io < 8; io++)
#ifdef notyetSCSI
               if (lp->d_type == DTYPE_SCSI) {
                       if (lp->d_partitions[io].p_offset == off)
                               break;
               } else
#endif
               if (lp->d_partitions[io].p_offset == off*lp->d_secpercyl)
                       break;

           if (io == 8) goto screwed;
           cyloffset = off;
       } else {
screwed:
               /* probably a bad or non-existant disklabel */
               io = 0 ;
               howto |= RB_SINGLE|RB_ASKNAME ;
       }

       /* construct bootdev */
       /* currently, PC has no way of booting off alternate controllers */
       bootdev = MAKEBOOTDEV(/*i_dev*/ dev, /*i_adapt*/0, /*i_ctlr*/0,
           unit, /*i_part*/io);

       printf("loading %s\n", bootprog);
       io = open(bootprog, 0);
       if (io >= 0)
               copyunix(io, howto);
       _stop("boot failed\n");
}

/*ARGSUSED*/
copyunix(io, howto)
       register io;    
{
       struct exec x;
       register int i;
       char *addr;

       i = read(io, (char *)&x, sizeof x);
       if (i != sizeof x ||
           (x.a_magic != 0407 && x.a_magic != 0413 && x.a_magic != 0410))
               _stop("Bad format\n");

       if ((x.a_magic == 0413 || x.a_magic == 0410) &&
           lseek(io, 0x400, 0) == -1)
               goto shread;

       if (read(io, (char *)0, x.a_text) != x.a_text)
               goto shread;

       addr = (char *)x.a_text;
       if (x.a_magic == 0413 || x.a_magic == 0410)
               while ((int)addr & CLOFSET)
                       *addr++ = 0;

       if (read(io, addr, x.a_data) != x.a_data)
               goto shread;

       addr += x.a_data;
       for (i = 0; i < x.a_bss; i++)
               *addr++ = 0;

       (*((int (*)()) x.a_entry))(howto, opendev, cyloffset);
       return;
shread:
       _stop("Short read\n");
}