Chnage MACHINE_NONCONTIG implementation such that the message buffer is

always located at the end of onboard RAM. This allows locore.s to zero
any offboard RAM to initialise the parity bit which most VMEbus RAM cards
have. Without this, many cards buserr on the first read access.
Thanks to Herb Peyerl for the idea.

sys/arch/mvme68k/mvme68k/locore.s

@@ -1,4 +1,4 @@
-/*	$NetBSD: locore.s,v 1.29 1997/10/21 19:25:16 scw Exp $	*/
+/*	$NetBSD: locore.s,v 1.30 1997/11/01 17:56:49 scw Exp $	*/
 
 /*
  * Copyright (c) 1988 University of Utah.
@@ -183,12 +183,36 @@ start:					| start of kernel and .text!
 	movl	0xfffe0774,d1		| End + 1 of onboard memory
 	movl	d1,a0@(4)		| phys_seg_list[0].ps_end
 	clrl	a0@(8)			| phys_seg_list[0].ps_startpage
-	movl	0xfffe0764,a0@(0x0c)	| Start of offboard segment
+
+	/* offboard RAM */
+	clrl	a0@(0x0c)		| phys_seg_list[1].ps_start
+	movl	#NBPG-1,d0
+	addl	0xfffe0764,d0		| Start of offboard segment
+	andl	#-NBPG,d0		| Round up to page boundary
 	beq	Lsavmaxmem		| Jump if none defined
-	movl	0xfffe0768,d1		| End of offboard segment
+	movl	#NBPG,d1		| Note: implicit '+1'
-	addql	#1,d1			| +1
+	addl	0xfffe0768,d1		| End of offboard segment
+	andl	#-NBPG,d1		| Round up to page boundary
+	cmpl	d1,d0			| Quick and dirty validity check
+	bcss	Loff_ok			| Yup, looks good.
+	movel	a0@(4),d1		| Just use onboard RAM otherwise
+	bras	Lsavmaxmem
+Loff_ok:
+	movl	d0,a0@(0x0c)		| phys_seg_list[1].ps_start
 	movl	d1,a0@(0x10)		| phys_seg_list[1].ps_end
 	clrl	a0@(0x14)		| phys_seg_list[1].ps_startpage
+
+	/*
+	 * Offboard RAM needs to be cleared to zero to initialise parity
+	 * on most VMEbus RAM cards. Without this, some cards will buserr
+	 * when first read.
+	 */
+	movel	d0,a0			| offboard start address again.
+Lclearoff:
+	clrl	a0@+			| zap a word
+	cmpl	a0,d1			| reached end?
+	bnes	Lclearoff
+
 Lsavmaxmem:
 	moveq	#PGSHIFT,d2
 	lsrl	d2,d1			| convert to page (click) number

sys/arch/mvme68k/mvme68k/machdep.c

@@ -1,4 +1,4 @@
-/*	$NetBSD: machdep.c,v 1.28 1997/10/19 10:53:14 scw Exp $	*/
+/*	$NetBSD: machdep.c,v 1.29 1997/11/01 17:56:47 scw Exp $	*/
 
 /*
  * Copyright (c) 1988 University of Utah.
@@ -87,10 +87,15 @@
 #include <machine/prom.h>
 #include <machine/psl.h>
 #include <machine/pte.h>
+#include <machine/vmparam.h>
 #include <dev/cons.h>
 
 #include <machine/kcore.h>	/* XXX should be pulled in by sys/kcore.h */
 
+#ifdef MACHINE_NONCONTIG
+#include <mvme68k/mvme68k/seglist.h>
+#endif
+
 #define	MAXMEM	64*1024*CLSIZE	/* XXX - from cmap.h */
 
 /* the following is used externally (sysctl_hw) */
@@ -219,10 +224,17 @@ mvme68k_init()
 	 * Initialize error message buffer (at end of core).
 	 * avail_end was pre-decremented in pmap_bootstrap to compensate.
 	 */
+#ifdef MACHINE_NONCONTIG
+#define MVME_MSG_BUF_START	phys_seg_list[0].ps_end
+#else
+#define MVME_MSG_BUF_START	avail_end
+#endif
 	for (i = 0; i < btoc(MSGBUFSIZE); i++)
 		pmap_enter(pmap_kernel(), (vm_offset_t)msgbufaddr + i * NBPG,
-		    avail_end + i * NBPG, VM_PROT_ALL, TRUE);
+		    MVME_MSG_BUF_START + i * NBPG, VM_PROT_ALL, TRUE);
 	initmsgbuf(msgbufaddr, round_page(MSGBUFSIZE));
+
+#undef MVME_MSG_BUF_START
 }
 
 #ifdef MVME147
@@ -334,7 +346,18 @@ cpu_startup()
 	 */
 	printf(version);
 	identifycpu();
-	printf("real mem  = %d\n", ctob(physmem));
+	printf("real mem  = %d", ctob(physmem));
+
+#ifdef MACHINE_NONCONTIG
+    maxaddr = 0;
+	for (i = 1; i < MAX_PHYS_SEGS && phys_seg_list[i].ps_start; i++)
+		maxaddr += phys_seg_list[i].ps_end - phys_seg_list[i].ps_start;
+
+	if ( maxaddr )
+		printf(" (of which %d is offboard)", maxaddr);
+#endif
+
+	printf("\n");
 
 	/*
 	 * Fine out how much space we need, allocate it,

sys/arch/mvme68k/mvme68k/pmap_bootstrap.c

@@ -1,4 +1,4 @@
-/*	$NetBSD: pmap_bootstrap.c,v 1.5 1997/10/09 21:39:33 scw Exp $	*/
+/*	$NetBSD: pmap_bootstrap.c,v 1.6 1997/11/01 17:56:51 scw Exp $	*/
 
 /* 
  * Copyright (c) 1991, 1993
@@ -410,16 +410,28 @@ pmap_bootstrap(nextpa, firstpa)
 	 * the pmap module.
 	 */
 	RELOC(avail_start, vm_offset_t) = nextpa;
+
+#ifndef MACHINE_NONCONTIG
 	RELOC(avail_end, vm_offset_t) =
 		m68k_ptob(RELOC(maxmem, int))
 			/* XXX allow for msgbuf */
 			- m68k_round_page(MSGBUFSIZE);
 
-#ifdef MACHINE_NONCONTIG
+#else
 	RELOC(avail_next, vm_offset_t) = RELOC(avail_start, vm_offset_t);
+
+	/* leave space at end of onboard RAM for message buffer */
+	RELOC(phys_seg_list[0].ps_end, vm_offset_t) -=
+		m68k_round_page(MSGBUFSIZE);
+
+	/* initial avail_end is end of onboard RAM */
+	RELOC(avail_end, vm_offset_t) =
+		m68k_ptob(RELOC(phys_seg_list[0].ps_end, vm_offset_t));
+
 	RELOC(avail_remaining, vm_size_t) =
 		(RELOC(phys_seg_list[0].ps_end, vm_offset_t) -
 		 RELOC(avail_start, vm_offset_t)) >> PGSHIFT;
+
 	RELOC(phys_seg_list[0].ps_start, vm_offset_t) = 
 		RELOC(avail_start, vm_offset_t);
 	RELOC(phys_seg_list[0].ps_startpage, vm_offset_t) = 0;
@@ -430,8 +442,7 @@ pmap_bootstrap(nextpa, firstpa)
 		     RELOC(phys_seg_list[0].ps_start, vm_offset_t)) / NBPG;
 
 	/* iterate over any remaining segments */
-	for (i = 1; i < MAX_PHYS_SEGS; i++)
+	for (i = 1; i < MAX_PHYS_SEGS; i++) {
-	{
 		vm_offset_t	len;
 
 		if ( RELOC(phys_seg_list[i].ps_start, vm_offset_t) == 0 )
@@ -448,12 +459,15 @@ pmap_bootstrap(nextpa, firstpa)
 
 		RELOC(avail_remaining, vm_size_t) += (len / NBPG);
 		RELOC(physmem, int) += (len / NBPG);
-	}
 
-	/* correct for message buffer */
+		if ( m68k_ptob(RELOC(phys_seg_list[i].ps_end, vm_offset_t)) >
-	RELOC(phys_seg_list[i - 1].ps_end, vm_offset_t) -=
+			RELOC(avail_end, vm_offset_t) ) {
-				m68k_round_page(MSGBUFSIZE);
+			RELOC(avail_end, vm_offset_t) =
+				m68k_ptob(RELOC(phys_seg_list[i].ps_end, vm_offset_t));
+		}
+	}
 #endif
+
 	RELOC(mem_size, vm_size_t) = m68k_ptob(RELOC(physmem, int));
 	RELOC(virtual_avail, vm_offset_t) =
 		VM_MIN_KERNEL_ADDRESS + (nextpa - firstpa);