Included below is a patch to allow users to mount primary DOS
partitions on disks with no NetBSD partition.  The patch does
essentially two things:

	1. It puts the primary MBR partitions in the default disklabel
	   as partitions e, f, g, and h (i.e. after the raw
	   partition).

	2. When it installs an MBR partition in the disklabel, it
	   compares the MBR partition type against four FAT filesystem
	   types; if it matches any of them, the disklabel partition
	   gets a p_type of FS_MSDOS.

The patch is straightforward, and I've tested it.  I'll check this in
in a few days if there aren't objections.

*** sys/arch/i386/include/disklabel.h	1996/03/02 07:44:35	1.1
--- sys/arch/i386/include/disklabel.h	1996/03/02 07:54:39
***************
*** 59,64 ****
--- 59,68 ----
  /* Known DOS partition types. */
  #define	DOSPTYP_386BSD	0xa5		/* 386BSD partition type */
  #define DOSPTYP_NETBSD	DOSPTYP_386BSD	/* NetBSD partition type (XXX) */
+ #define DOSPTYP_FAT12	0x1		/* 12-bit FAT */
+ #define DOSPTYP_FAT16S	0x4		/* 16-bit FAT, less than 32M */
+ #define DOSPTYP_FAT16B	0x6		/* 16-bit FAT, more than 32M */
+ #define DOSPTYP_FAT16C	0xe		/* 16-bit FAT, CHS-mapped */
  
  #include <sys/dkbad.h>
  struct cpu_disklabel {
*** sys/arch/i386/i386/disksubr.c	1996/03/01 22:21:56	1.1
--- sys/arch/i386/i386/disksubr.c	1996/03/02 08:33:53
***************
*** 43,48 ****
--- 43,51 ----
  
  #define	b_cylin	b_resid
  
+ int fat_types[] = { DOSPTYP_FAT12, DOSPTYP_FAT16S,
+ 		    DOSPTYP_FAT16B, DOSPTYP_FAT16C, -1 };
+ 
  /*
   * Attempt to read a disk label from a device
   * using the indicated stategy routine.
***************
*** 66,71 ****
--- 69,75 ----
  	struct cpu_disklabel *osdep;
  {
  	struct dos_partition *dp = osdep->dosparts;
+ 	struct partition *pp;
  	struct dkbad *bdp = &osdep->bad;
  	struct buf *bp;
  	struct disklabel *dlp;
***************
*** 109,115 ****
  			/* XXX how do we check veracity/bounds of this? */
  			bcopy(bp->b_data + DOSPARTOFF, dp,
  			    NDOSPART * sizeof(*dp));
! 			for (i = 0; i < NDOSPART; i++, dp++)
  				/* is this ours? */
  				if (dp->dp_size && dp->dp_typ == DOSPTYP_386BSD
  				    && dospartoff == 0) {
--- 113,128 ----
  			/* XXX how do we check veracity/bounds of this? */
  			bcopy(bp->b_data + DOSPARTOFF, dp,
  			    NDOSPART * sizeof(*dp));
! 			for (i = 0; i < NDOSPART; i++, dp++) {
! 				/* Install in partition e, f, g, or h. */
! 				pp = &lp->d_partitions[RAW_PART + 1 + i];
! 				pp->p_offset = dp->dp_start;
! 				pp->p_size = dp->dp_size;
! 				for (ip = fat_types; *ip != -1; ip++) {
! 				    if (dp->dp_typ == *ip)
! 					pp->p_fstype = FS_MSDOS;
! 				}
! 
  				/* is this ours? */
  				if (dp->dp_size && dp->dp_typ == DOSPTYP_386BSD
  				    && dospartoff == 0) {
***************
*** 128,135 ****
  					lp->d_secpercyl =
  					    lp->d_ntracks * lp->d_nsectors;
  				}
  		}
- 			
  	}
  	
  	/* next, dig out disk label */
--- 141,149 ----
  					lp->d_secpercyl =
  					    lp->d_ntracks * lp->d_nsectors;
  				}
+ 			}
+ 			lp->d_npartitions = RAW_PART + 1 + i;
  		}
  	}
  	
  	/* next, dig out disk label */