add some documentation

add some predefined constants so that the kernel can generate valid
bootblocks without help from 'wrtvid'

1 files changed, 98 insertions, 68 deletions

diff --git a/sys/arch/mvme68k/include/disklabel.h b/sys/arch/mvme68k/include/disklabel.h
index 78741c4c925..bf4bfe1765f 100644
--- a/sys/arch/mvme68k/include/disklabel.h
+++ b/sys/arch/mvme68k/include/disklabel.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: disklabel.h,v 1.2 1996/04/28 10:56:12 deraadt Exp $ */
+/*	$OpenBSD: disklabel.h,v 1.3 1996/05/10 03:18:43 chuck Exp $ */
 
 /*
  * Copyright (c) 1995 Dale Rahn.
@@ -34,7 +34,7 @@
 #define _MACHINE_DISKLABEL_H_
 
 /* number of boot pieces , ie xxboot bootxx */
-#define NUMBOOT		2
+#define NUMBOOT		0
 
 #define	PARTITIONSHIFT	4
 
@@ -52,79 +52,109 @@
 #define MAKEDISKDEV(maj, unit, part) \
     (makedev((maj), ((unit) * MAXPARTITIONS) + (part)))
 
+/*
+ * a cpu_disklabel is a disklabel that the bug (prom) can understand
+ * and live with.   the bug works in terms of 256 byte blocks.   in our
+ * case the first two bug blocks make up the cpu_disklabel (which is 512
+ * bytes [i.e. one sector] in length).
+ *
+ * we use a fixed layout the BSD disk structure (in 256 byte blocks):
+ *   block 0  = the volume ID block  (part of cpu_disklabel)
+ *   block 1  = media configuration area (part of cpu_disklabel)
+ *   block 2  = start of first level OS bootstrap (continues ...)
+ *   block 31 = end of OS bootstrap
+ *   block 32 = BSD filesystem superblock
+ *
+ * this gives us 30 blocks (30*256 = 7680 bytes) for the bootstrap's text+data
+ *
+ * disksubr.c translates between cpu_disklabel and BSD disklabel.
+ *
+ */
+
 struct cpu_disklabel {
 	/* VID */
-	u_char		vid_id[4];
-	u_char		vid_0[16];
-	u_int		vid_oss;
-	u_short		vid_osl;
-	u_char		vid_1[4];
-	u_short		vid_osa_u;
-	u_short		vid_osa_l;
-	u_char		vid_2[2];
-	u_short		partitions;
-	u_char		vid_vd[16];
-	u_long		bbsize;
-	u_long		magic1;		/* 4 */
-	u_short		type;		/* 2 */
-	u_short		subtype;	/* 2 */
-	u_char		packname[16];	/* 16 */
-	u_long		flags;		/* 4 */
-	u_long		drivedata[5];	/* 4 */
-	u_long		spare[5];	/* 4 */
-	u_short		checksum;	/* 2 */
+	u_char  vid_id[4];	/* volume ID */
+#define VID_ID		"NBSD"
+	u_char  vid_0[16];
+	u_int   vid_oss;	/* starting block # of bootstrap */
+#define VID_OSS		2
+	u_short	vid_osl;	/* bootstrap length (30 blocks) */
+#define VID_OSL		30
+	u_char	vid_1[4];
+	u_short	vid_osa_u;	/* bootstrap start address (upper) */
+	u_short	vid_osa_l;	/* bootstrap start address (lower) */
+#define VID_OSA		0x3f0000	/* MUST match bootstrap code */
+#define VID_OSAU	((VID_OSA >> 16) & 0xffff)
+#define VID_OSAL	(VID_OSA & 0xffff)
+	u_char	vid_2[2];
+	u_short	partitions;
+	u_char	vid_vd[16];
+	u_long	bbsize;
+	u_long	magic1;		/* 4 */
+	u_short	type;		/* 2 */
+	u_short	subtype;	/* 2 */
+	u_char	packname[16];	/* 16 */
+	u_long	flags;		/* 4 */
+	u_long	drivedata[5];	/* 4 */
+	u_long	spare[5];	/* 4 */
+	u_short	checksum;	/* 2 */
 
-	u_long		secpercyl;	/* 4 */
-	u_long		secperunit;	/* 4 */
-	u_long		headswitch;	/* 4 */
+	u_long	secpercyl;	/* 4 */
+	u_long	secperunit;	/* 4 */
+	u_long	headswitch;	/* 4 */
 
-	u_char		vid_3[4];
-	u_int		vid_cas;
-	u_char		vid_cal;
-	u_char		vid_4_0[3];
-	u_char		vid_4[64];
-	u_char		vid_4_1[28];
-	u_long		sbsize;
-	u_char		vid_mot[8];
+	u_char	vid_3[4];
+	u_int	vid_cas;	/* block # of CFG area, hardwired at 1 */
+#define VID_CAS		1
+	u_char	vid_cal;	/* length of CFG area, in blocks (1) */
+#define VID_CAL		1
+	u_char	vid_4_0[3];
+	u_char	vid_4[64];
+	u_char	vid_4_1[28];
+	u_long	sbsize;
+	u_char	vid_mot[8];	/* must contain "MOTOROLA" */
+#define VID_MOT		"MOTOROLA"
 
 	/* CFG */
-	u_char		cfg_0[4];
-	u_short		cfg_atm;
-	u_short		cfg_prm;
-	u_short		cfg_atw;
-	u_short		cfg_rec;
+	u_char	cfg_0[4];
+	u_short	cfg_atm;
+	u_short	cfg_prm;
+	u_short	cfg_atw;
+	u_short	cfg_rec;	/* block size (256) */
+#define	CFG_REC		256
 
-	u_short		sparespertrack;
-	u_short		sparespercyl;
-	u_long		acylinders;
-	u_short		rpm;
-	u_short		cylskew;
+	u_short	sparespertrack;
+	u_short	sparespercyl;
+	u_long	acylinders;
+	u_short	rpm;
+	u_short	cylskew;
 
-	u_char		cfg_spt;
-	u_char		cfg_hds;
-	u_short		cfg_trk;
-	u_char		cfg_ilv;
-	u_char		cfg_sof;
-	u_short		cfg_psm;
-	u_short		cfg_shd;
-	u_char		cfg_2[2];
-	u_short		cfg_pcom;
-	u_char		cfg_3;
-	u_char		cfg_ssr;
-	u_short		cfg_rwcc;
-	u_short		cfg_ecc;
-	u_short		cfg_eatm;
-	u_short		cfg_eprm;
-	u_short		cfg_eatw;
-	u_char		cfg_gpb1;
-	u_char		cfg_gpb2;
-	u_char		cfg_gpb3;
-	u_char		cfg_gpb4;
-	u_char		cfg_ssc;
-	u_char		cfg_runit;
-	u_short		cfg_rsvc1;
-	u_short		cfg_rsvc2;
-	u_long		magic2;
-	u_char		cfg_4[192];
+	u_char	cfg_spt;
+	u_char	cfg_hds;
+	u_short	cfg_trk;
+	u_char	cfg_ilv;
+	u_char	cfg_sof;
+	u_short	cfg_psm;	/* physical sector size (512) */
+#define CFG_PSM		512
+	u_short	cfg_shd;
+	u_char	cfg_2[2];
+	u_short	cfg_pcom;
+	u_char	cfg_3;
+	u_char	cfg_ssr;
+	u_short	cfg_rwcc;
+	u_short	cfg_ecc;
+	u_short	cfg_eatm;
+	u_short	cfg_eprm;
+	u_short	cfg_eatw;
+	u_char	cfg_gpb1;
+	u_char	cfg_gpb2;
+	u_char	cfg_gpb3;
+	u_char	cfg_gpb4;
+	u_char	cfg_ssc;
+	u_char	cfg_runit;
+	u_short	cfg_rsvc1;
+	u_short	cfg_rsvc2;
+	u_long	magic2;
+	u_char	cfg_4[192];
 };
 #endif _MACHINE_DISKLABEL_H_