enlarge msgbuf, somewhat line netbsd did

35 files changed, 250 insertions, 171 deletions

diff --git a/sbin/dmesg/dmesg.c b/sbin/dmesg/dmesg.c
index 7643ce9ce8c..2d14d1f3b68 100644
--- a/sbin/dmesg/dmesg.c
+++ b/sbin/dmesg/dmesg.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: dmesg.c,v 1.7 1998/07/08 22:14:37 deraadt Exp $	*/
+/*	$OpenBSD: dmesg.c,v 1.8 2000/02/22 19:27:38 deraadt Exp $	*/
 /*	$NetBSD: dmesg.c,v 1.8 1995/03/18 14:54:49 cgd Exp $	*/
 
 /*-
@@ -44,7 +44,7 @@ static char copyright[] =
 #if 0
 static char sccsid[] = "@(#)dmesg.c	8.1 (Berkeley) 6/5/93";
 #else
-static char rcsid[] = "$OpenBSD: dmesg.c,v 1.7 1998/07/08 22:14:37 deraadt Exp $";
+static char rcsid[] = "$OpenBSD: dmesg.c,v 1.8 2000/02/22 19:27:38 deraadt Exp $";
 #endif
 #endif /* not lint */
 
@@ -78,10 +78,10 @@ main(argc, argv)
 	int argc;
 	char *argv[];
 {
-	register int ch, newl, skip;
+	register int ch, newl, skip, i;
 	register char *p, *ep;
 	struct msgbuf *bufp, cur;
-	char *memf, *nlistf;
+	char *memf, *nlistf, *bufdata;
 	kvm_t *kd;
 	char buf[5];
 
@@ -127,21 +127,26 @@ main(argc, argv)
 	if (KREAD((long)bufp, cur))
 		errx(1, "kvm_read: %s (%0lx)", kvm_geterr(kd),
 		    (unsigned long)bufp);
-	kvm_close(kd);
 	if (cur.msg_magic != MSG_MAGIC)
 		errx(1, "magic number incorrect");
-	if (cur.msg_bufx >= MSG_BSIZE)
+	bufdata = malloc(cur.msg_bufs);
+	if (bufdata == NULL)
+		errx(1, "couldn't allocate space for buffer data");
+	if (kvm_read(kd, (long)&bufp->msg_bufc, bufdata,
+	    cur.msg_bufs) != cur.msg_bufs)
+		errx(1, "kvm_read: %s", kvm_geterr(kd));
+	if (cur.msg_bufx >= cur.msg_bufs)
 		cur.msg_bufx = 0;
+	kvm_close(kd);
 
 	/*
 	 * The message buffer is circular; start at the read pointer, and
 	 * go to the write pointer - 1.
 	 */
-	p = ep = cur.msg_bufc + (cur.msg_bufx - 1 + MSG_BSIZE) % MSG_BSIZE;
-	newl = skip = 0;
-	do {
-		if (++p == cur.msg_bufc + MSG_BSIZE)
-			p = cur.msg_bufc;
+	for (newl = skip = i = 0, p = bufdata + cur.msg_bufx;
+	    i < cur.msg_bufs; i++, p++) {
+		if (p == bufdata + cur.msg_bufs)
+			p = bufdata;
 		ch = *p;
 		/* Skip "\n<.*>" syslog sequences. */
 		if (skip) {
@@ -161,7 +166,7 @@ main(argc, argv)
 			(void)putchar(buf[0]);
 		else
 			(void)printf("%s", buf);
-	} while (p != ep);
+	}
 	if (!newl)
 		(void)putchar('\n');
 	exit(0);
diff --git a/sys/arch/alpha/alpha/machdep.c b/sys/arch/alpha/alpha/machdep.c
index 2512dfe1f4f..e80f92db679 100644
--- a/sys/arch/alpha/alpha/machdep.c
+++ b/sys/arch/alpha/alpha/machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: machdep.c,v 1.30 2000/02/09 06:01:15 itojun Exp $	*/
+/*	$OpenBSD: machdep.c,v 1.31 2000/02/22 19:27:40 deraadt Exp $	*/
 /*	$NetBSD: machdep.c,v 1.61 1996/12/07 01:54:49 cgd Exp $	*/
 
 /*
@@ -134,7 +134,6 @@ int	bufpages = BUFPAGES;
 #else
 int	bufpages = 0;
 #endif
-int	msgbufmapped = 0;	/* set when safe to use msgbuf */
 int	maxmem;			/* max memory per process */
 
 int	totalphysmem;		/* total amount of physical memory in system */
@@ -433,10 +432,13 @@ unknown_cputype:
 	/*
 	 * Initialize error message buffer (at end of core).
 	 */
-	lastusablepage -= btoc(sizeof (struct msgbuf));
-	msgbufp =
-	    (struct msgbuf *)ALPHA_PHYS_TO_K0SEG(ctob(lastusablepage + 1));
-	msgbufmapped = 1;
+	lastusablepage -= btoc(MSGBUFSIZE);
+	printf("%lx %d\n", (caddr_t)ALPHA_PHYS_TO_K0SEG(ctob(lastusablepage + 1)),
+	    MSGBUFSIZE);
+	initmsgbuf((caddr_t)ALPHA_PHYS_TO_K0SEG(ctob(lastusablepage + 1)),
+	    MSGBUFSIZE);
+	printf("%lx %d\n", (caddr_t)ALPHA_PHYS_TO_K0SEG(ctob(lastusablepage + 1)),
+	    MSGBUFSIZE);
 
 	/*
 	 * Allocate space for system data structures.
@@ -944,6 +946,7 @@ dumpsys()
 	daddr_t blkno;
 	int (*dump) __P((dev_t, daddr_t, caddr_t, size_t));
 	int error;
+	extern int msgbufmapped;
 
 	/* Save registers. */
 	savectx(&dumppcb);
diff --git a/sys/arch/alpha/include/param.h b/sys/arch/alpha/include/param.h
index 0350a8ded4d..0926d360936 100644
--- a/sys/arch/alpha/include/param.h
+++ b/sys/arch/alpha/include/param.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: param.h,v 1.10 1997/09/17 17:44:04 downsj Exp $	*/
+/*	$OpenBSD: param.h,v 1.11 2000/02/22 19:27:40 deraadt Exp $	*/
 /*	$NetBSD: param.h,v 1.15 1996/11/13 21:13:19 cgd Exp $	*/
 
 /*
@@ -109,6 +109,8 @@
 #endif
 #endif
 
+#define MSGBUFSIZE	8192
+
 /*
  * Size of kernel malloc arena in CLBYTES-sized logical pages
  */ 
diff --git a/sys/arch/amiga/amiga/machdep.c b/sys/arch/amiga/amiga/machdep.c
index 458526fb3e6..7aabe71fc55 100644
--- a/sys/arch/amiga/amiga/machdep.c
+++ b/sys/arch/amiga/amiga/machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: machdep.c,v 1.35 1999/12/08 06:50:14 itojun Exp $	*/
+/*	$OpenBSD: machdep.c,v 1.36 2000/02/22 19:27:42 deraadt Exp $	*/
 /*	$NetBSD: machdep.c,v 1.95 1997/08/27 18:31:17 is Exp $	*/
 
 /*
@@ -151,7 +151,6 @@ int	bufpages = BUFPAGES;
 #else
 int	bufpages = 0;
 #endif
-int	msgbufmapped;		/* set when safe to use msgbuf */
 int	maxmem;			/* max memory per process */
 int	physmem = MAXMEM;	/* max supported memory, changes to actual */
 /*
@@ -326,11 +325,11 @@ cpu_startup()
 	pmapdebug = 0;
 #endif
 	/* avail_end was pre-decremented in pmap_bootstrap to compensate */
-	for (i = 0; i < btoc(sizeof (struct msgbuf)); i++)
+	for (i = 0; i < btoc(MSGBUFSIZE); i++)
 		pmap_enter(pmap_kernel(), (vm_offset_t)msgbufp, 
 		    avail_end + i * NBPG, VM_PROT_READ|VM_PROT_WRITE, TRUE,
 		    VM_PROT_READ|VM_PROT_WRITE);
-	msgbufmapped = 1;
+	initmsgbuf((caddr_t)msgbufp, round_page(MSGBUFSIZE));
 
 	/*
 	 * Good {morning,afternoon,evening,night}.
@@ -873,6 +872,7 @@ dumpsys()
 	kcore_seg_t *kseg_p;
 	cpu_kcore_hdr_t *chdr_p;
 	char	dump_hdr[dbtob(1)];	/* XXX assume hdr fits in 1 block */
+	extern int msgbufmapped;
 
 	msgbufmapped = 0;
 	if (dumpdev == NODEV)
diff --git a/sys/arch/amiga/amiga/pmap.c b/sys/arch/amiga/amiga/pmap.c
index baf16996364..120e274e6c5 100644
--- a/sys/arch/amiga/amiga/pmap.c
+++ b/sys/arch/amiga/amiga/pmap.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap.c,v 1.16 1999/09/03 18:00:29 art Exp $	*/
+/*	$OpenBSD: pmap.c,v 1.17 2000/02/22 19:27:42 deraadt Exp $	*/
 /*	$NetBSD: pmap.c,v 1.39 1997/06/10 18:26:41 veego Exp $	*/
 
 /* 
@@ -295,7 +295,6 @@ void pmap_pvdump __P((vm_offset_t));
  */
 caddr_t	CADDR1, CADDR2, vmmap;
 u_int	*CMAP1, *CMAP2, *vmpte, *msgbufmap;
-struct msgbuf	*msgbufp;
 
 /*
  *	Bootstrap the system enough to run with virtual memory.
@@ -324,7 +323,7 @@ pmap_bootstrap(firstaddr, loadaddr)
 	avail_end = maxmem << PGSHIFT;
 
 	/* XXX: allow for msgbuf */
-	avail_end -= m68k_round_page(sizeof(struct msgbuf));
+	avail_end -= m68k_round_page(MSGBUFSIZE);
 #ifdef MACHINE_NONCONTIG
 	/*
 	 * first segment of memory is always the one loadbsd found
@@ -423,7 +422,7 @@ pmap_bootstrap(firstaddr, loadaddr)
 	SYSMAP(caddr_t		,CMAP1		,CADDR1	   ,1		)
 	SYSMAP(caddr_t		,CMAP2		,CADDR2	   ,1		)
 	SYSMAP(caddr_t		,vmpte		,vmmap	   ,1		)
-	SYSMAP(struct msgbuf *	,msgbufmap	,msgbufp   ,1		)
+	SYSMAP(struct msgbuf *	,msgbufmap	,msgbufp   ,btoc(MSGBUFSIZE))
 
 	virtual_avail = reserve_dumppages(va);
 }
diff --git a/sys/arch/amiga/include/param.h b/sys/arch/amiga/include/param.h
index 5b04b0daf87..12da70cf30b 100644
--- a/sys/arch/amiga/include/param.h
+++ b/sys/arch/amiga/include/param.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: param.h,v 1.10 1997/09/18 13:40:02 niklas Exp $	*/
+/*	$OpenBSD: param.h,v 1.11 2000/02/22 19:27:43 deraadt Exp $	*/
 /*	$NetBSD: param.h,v 1.35 1997/07/10 08:22:36 veego Exp $	*/
 
 /*
@@ -75,6 +75,8 @@
 #define	NKMEMCLUSTERS	(3072 * 1024 / CLBYTES)
 #endif
 
+#define MSGBUFSIZE	8192
+
 /*
  * spl functions; all are normally done in-line
  */
diff --git a/sys/arch/hp300/hp300/machdep.c b/sys/arch/hp300/hp300/machdep.c
index 323c8fd9cab..170b07c5137 100644
--- a/sys/arch/hp300/hp300/machdep.c
+++ b/sys/arch/hp300/hp300/machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: machdep.c,v 1.38 1999/09/03 18:00:41 art Exp $	*/
+/*	$OpenBSD: machdep.c,v 1.39 2000/02/22 19:27:46 deraadt Exp $	*/
 /*	$NetBSD: machdep.c,v 1.94 1997/06/12 15:46:29 mrg Exp $	*/
 
 /*
@@ -133,7 +133,6 @@ int	bufpages = BUFPAGES;
 #else
 int	bufpages = 0;
 #endif
-int	msgbufmapped;		/* set when safe to use msgbuf */
 int	maxmem;			/* max memory per process */
 int	physmem = MAXMEM;	/* max supported memory, changes to actual */
 /*
@@ -247,11 +246,11 @@ cpu_startup()
 	 * Initialize error message buffer (at end of core).
 	 * avail_end was pre-decremented in pmap_bootstrap to compensate.
 	 */
-	for (i = 0; i < btoc(sizeof (struct msgbuf)); i++)
+	for (i = 0; i < btoc(MSGBUFSIZE); i++)
 		pmap_enter(pmap_kernel(), (vm_offset_t)msgbufp,
 		    avail_end + i * NBPG, VM_PROT_READ|VM_PROT_WRITE, TRUE,
 		    VM_PROT_READ|VM_PROT_WRITE);
-	msgbufmapped = 1;
+	initmsgbuf((caddr_t)msgbufp, round_page(MSGBUFSIZE));
 
 	/*
 	 * Good {morning,afternoon,evening,night}.
@@ -889,6 +888,7 @@ dumpsys()
 	cpu_kcore_hdr_t *chdr_p;
 	char dump_hdr[dbtob(1)];	/* XXX assume hdr fits in 1 block */
 #endif	/* HP300_NEWKVM */
+	extern int msgbufmapped;
 
 	/* XXX initialized here because of gcc lossage */
 	maddr = lowram;
diff --git a/sys/arch/hp300/hp300/pmap_bootstrap.c b/sys/arch/hp300/hp300/pmap_bootstrap.c
index 26227b80ae9..5d06ae30f1b 100644
--- a/sys/arch/hp300/hp300/pmap_bootstrap.c
+++ b/sys/arch/hp300/hp300/pmap_bootstrap.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap_bootstrap.c,v 1.6 1998/03/07 12:41:33 deraadt Exp $	*/
+/*	$OpenBSD: pmap_bootstrap.c,v 1.7 2000/02/22 19:27:46 deraadt Exp $	*/
 /*	$NetBSD: pmap_bootstrap.c,v 1.13 1997/06/10 18:56:50 veego Exp $	*/
 
 /* 
@@ -85,7 +85,6 @@ void	pmap_bootstrap __P((vm_offset_t, vm_offset_t));
  *	msgbufp:	kernel message buffer
  */
 caddr_t		CADDR1, CADDR2, vmmap, ledbase;
-struct msgbuf	*msgbufp;
 
 /*
  * Bootstrap the VM system.
@@ -438,7 +437,7 @@ pmap_bootstrap(nextpa, firstpa)
 	 */
 	RELOC(avail_start, vm_offset_t) = nextpa;
 	RELOC(avail_end, vm_offset_t) = m68k_ptob(RELOC(maxmem, int)) -
-	    (m68k_round_page(sizeof(struct msgbuf)) + m68k_ptob(1));
+	    (m68k_round_page(MSGBUFSIZE) + m68k_ptob(1));
 	RELOC(mem_size, vm_size_t) = m68k_ptob(RELOC(physmem, int));
 	RELOC(virtual_avail, vm_offset_t) =
 		VM_MIN_KERNEL_ADDRESS + (nextpa - firstpa);
@@ -525,7 +524,7 @@ pmap_bootstrap(nextpa, firstpa)
 		RELOC(ledbase, caddr_t) = (caddr_t)va;
 		va += NBPG;
 		RELOC(msgbufp, struct msgbuf *) = (struct msgbuf *)va;
-		va += NBPG;
+		va += MSGBUFSIZE;
 		RELOC(virtual_avail, vm_offset_t) = va;
 	}
 }
diff --git a/sys/arch/hp300/include/param.h b/sys/arch/hp300/include/param.h
index a81227f6093..69eaaed41a8 100644
--- a/sys/arch/hp300/include/param.h
+++ b/sys/arch/hp300/include/param.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: param.h,v 1.9 1997/07/13 09:48:02 downsj Exp $	*/
+/*	$OpenBSD: param.h,v 1.10 2000/02/22 19:27:46 deraadt Exp $	*/
 /*	$NetBSD: param.h,v 1.35 1997/07/10 08:22:38 veego Exp $	*/
 
 /*
@@ -77,6 +77,8 @@
 # define	NKMEMCLUSTERS	(2048 * 1024 / CLBYTES)
 #endif
 
+#define MSGBUFSIZE 4096
+
 #if defined(_KERNEL) && !defined(_LOCORE)
 #define	delay(us)	_delay((us) << 8)
 #define DELAY(us)	delay(us)
diff --git a/sys/arch/i386/i386/machdep.c b/sys/arch/i386/i386/machdep.c
index 58bcba53120..4aaee78bf0a 100644
--- a/sys/arch/i386/i386/machdep.c
+++ b/sys/arch/i386/i386/machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: machdep.c,v 1.124 2000/02/08 00:14:12 niklas Exp $	*/
+/*	$OpenBSD: machdep.c,v 1.125 2000/02/22 19:27:48 deraadt Exp $	*/
 /*	$NetBSD: machdep.c,v 1.214 1996/11/10 03:16:17 thorpej Exp $	*/
 
 /*-
@@ -226,9 +226,6 @@ long	dumplo = 0; 		/* blocks */
 
 int	cpu_class;
 
-struct	msgbuf *msgbufp;
-int	msgbufmapped;
-
 bootarg_t *bootargp;
 vm_offset_t avail_end;
 
@@ -319,19 +316,18 @@ cpu_startup()
 	 * (space reserved in /boot)
 	 */
 	pa = avail_end;
-	for (i = 0; i < btoc(sizeof(struct msgbuf)); i++, pa += NBPG)
+	for (i = 0; i < btoc(MSGBUFSIZE); i++, pa += NBPG)
 		pmap_enter(pmap_kernel(),
 		    (vm_offset_t)((caddr_t)msgbufp + i * NBPG), pa,
 		    VM_PROT_READ|VM_PROT_WRITE, TRUE,
 		    VM_PROT_READ|VM_PROT_WRITE);
-
-	msgbufmapped = 1;
+	initmsgbuf((caddr_t)msgbufp, round_page(MSGBUFSIZE));
 
 	printf(version);
 	startrtclock();
 	
 	identifycpu();
-	printf("real mem  = %d\n", ctob(physmem));
+	printf("real mem  = %u (%uK)\n", ctob(physmem), ctob(physmem)/1024);
 
 	/*
 	 * Find out how much space we need, allocate it,
@@ -399,12 +395,14 @@ cpu_startup()
 		callout[i-1].c_next = &callout[i];
 
 #if defined(UVM)
-	printf("avail mem = %ld\n", ptoa(uvmexp.free));
+	printf("avail mem = %lu (%uK)\n", ptoa(uvmexp.free),
+	    ptoa(uvmexp.free)/1024);
 #else
-	printf("avail mem = %ld\n", ptoa(cnt.v_free_count));
+	printf("avail mem = %lu (%uK)\n", ptoa(cnt.v_free_count),
+	    ptoa(cnt.v_free_count)/1024);
 #endif
-	printf("using %d buffers containing %d bytes of memory\n",
-		nbuf, bufpages * CLBYTES);
+	printf("using %d buffers containing %u bytes (%uK) of memory\n",
+		nbuf, bufpages * CLBYTES, bufpages * CLBYTES / 1024);
 
 	/*
 	 * Set up buffers, so they can be used to read disk labels.
@@ -1636,6 +1634,7 @@ dumpsys()
 	int (*dump) __P((dev_t, daddr_t, caddr_t, size_t));
 	int error;
 	register char *str;
+	extern int msgbufmapped;
 
 	/* Save registers. */
 	savectx(&dumppcb);
@@ -2049,7 +2048,7 @@ init386(first_avail)
 		}
 
 	ndumpmem = i;
-	avail_end -= i386_round_page(sizeof(struct msgbuf));
+	avail_end -= i386_round_page(MSGBUFSIZE);
 
 #ifdef DEBUG
 	printf(": %lx\n", avail_end);
diff --git a/sys/arch/i386/i386/pmap.c b/sys/arch/i386/i386/pmap.c
index ec96fd20324..2371786f1e8 100644
--- a/sys/arch/i386/i386/pmap.c
+++ b/sys/arch/i386/i386/pmap.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap.c,v 1.34 2000/01/29 21:41:51 mickey Exp $	*/
+/*	$OpenBSD: pmap.c,v 1.35 2000/02/22 19:27:48 deraadt Exp $	*/
 /*	$NetBSD: pmap.c,v 1.36 1996/05/03 19:42:22 christos Exp $	*/
 
 /*
@@ -280,8 +280,7 @@ pmap_bootstrap(virtual_start)
 	SYSMAP(caddr_t		,CMAP1		,CADDR1	   ,1		)
 	SYSMAP(caddr_t		,CMAP2		,CADDR2	   ,1		)
 	SYSMAP(caddr_t		,XXX_mmap	,vmmap	   ,1		)
-	SYSMAP(struct msgbuf *	,msgbufmap	,msgbufp   ,
-	    btoc(sizeof(struct msgbuf))		)
+	SYSMAP(struct msgbuf *	,msgbufmap	,msgbufp   ,btoc(MSGBUFSIZE))
 	SYSMAP(bootarg_t *	,bootargmap	,bootargp  ,btoc(bootargc))
 	virtual_avail = va;
 #endif
diff --git a/sys/arch/i386/i386/pmap.old.c b/sys/arch/i386/i386/pmap.old.c
index 3c896a9a72f..809e80b7131 100644
--- a/sys/arch/i386/i386/pmap.old.c
+++ b/sys/arch/i386/i386/pmap.old.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap.old.c,v 1.34 2000/01/29 21:41:51 mickey Exp $	*/
+/*	$OpenBSD: pmap.old.c,v 1.35 2000/02/22 19:27:48 deraadt Exp $	*/
 /*	$NetBSD: pmap.c,v 1.36 1996/05/03 19:42:22 christos Exp $	*/
 
 /*
@@ -280,8 +280,7 @@ pmap_bootstrap(virtual_start)
 	SYSMAP(caddr_t		,CMAP1		,CADDR1	   ,1		)
 	SYSMAP(caddr_t		,CMAP2		,CADDR2	   ,1		)
 	SYSMAP(caddr_t		,XXX_mmap	,vmmap	   ,1		)
-	SYSMAP(struct msgbuf *	,msgbufmap	,msgbufp   ,
-	    btoc(sizeof(struct msgbuf))		)
+	SYSMAP(struct msgbuf *	,msgbufmap	,msgbufp   ,btoc(MSGBUFSIZE))
 	SYSMAP(bootarg_t *	,bootargmap	,bootargp  ,btoc(bootargc))
 	virtual_avail = va;
 #endif
diff --git a/sys/arch/i386/include/param.h b/sys/arch/i386/include/param.h
index eedfe26d667..ed1128db081 100644
--- a/sys/arch/i386/include/param.h
+++ b/sys/arch/i386/include/param.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: param.h,v 1.9 1999/11/27 16:25:32 deraadt Exp $	*/
+/*	$OpenBSD: param.h,v 1.10 2000/02/22 19:27:48 deraadt Exp $	*/
 /*	$NetBSD: param.h,v 1.29 1996/03/04 05:04:26 cgd Exp $	*/
 
 /*-
@@ -93,6 +93,10 @@
 #define	UPAGES		2		/* pages of u-area */
 #define	USPACE		(UPAGES * NBPG)	/* total size of u-area */
 
+#ifndef MSGBUFSIZE
+#define MSGBUFSIZE	2*NBPG		/* default message buffer size */
+#endif
+
 /*
  * Constants related to network buffer management.
  * MCLBYTES must be no larger than CLBYTES (the software page size), and,
diff --git a/sys/arch/mac68k/include/param.h b/sys/arch/mac68k/include/param.h
index eff676c12d0..c73f5ac21b3 100644
--- a/sys/arch/mac68k/include/param.h
+++ b/sys/arch/mac68k/include/param.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: param.h,v 1.9 1999/04/24 06:39:40 downsj Exp $	*/
+/*	$OpenBSD: param.h,v 1.10 2000/02/22 19:27:51 deraadt Exp $	*/
 /*	$NetBSD: param.h,v 1.28 1997/03/01 06:57:45 scottr Exp $	*/
 
 /*
@@ -110,6 +110,8 @@
 #define	NKMEMCLUSTERS	(2048 * 1024 / CLBYTES)
 #endif
 
+#define MSGBUFSIZE	4096
+
 #if defined(_KERNEL) && !defined(_LOCORE)
 void	delay		__P((unsigned));
 #define DELAY(ms)	delay(ms)
diff --git a/sys/arch/mac68k/mac68k/machdep.c b/sys/arch/mac68k/mac68k/machdep.c
index d27edd00388..88f09533e26 100644
--- a/sys/arch/mac68k/mac68k/machdep.c
+++ b/sys/arch/mac68k/mac68k/machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: machdep.c,v 1.64 1999/12/08 06:50:16 itojun Exp $	*/
+/*	$OpenBSD: machdep.c,v 1.65 2000/02/22 19:27:52 deraadt Exp $	*/
 /*	$NetBSD: machdep.c,v 1.134 1997/02/14 06:15:30 scottr Exp $	*/
 
 /*
@@ -201,7 +201,6 @@ int     bufpages = BUFPAGES;
 int     bufpages = 0;
 #endif
 
-int     msgbufmapped;		/* set when safe to use msgbuf */
 int     maxmem;			/* max memory per process */
 int     physmem = MAXMEM;	/* max supported memory, changes to actual */
 
@@ -310,12 +309,12 @@ cpu_startup(void)
 	 * Initialize error message buffer (at end of core).
 	 * high[numranges-1] was decremented in pmap_bootstrap.
 	 */
-	for (i = 0; i < btoc(sizeof(struct msgbuf)); i++)
+	for (i = 0; i < btoc(MSGBUFSIZE); i++)
 		pmap_enter(pmap_kernel(), (vm_offset_t) msgbufp,
 		    high[numranges - 1] + i * NBPG,
 		    VM_PROT_READ|VM_PROT_WRITE, TRUE,
 		    VM_PROT_READ|VM_PROT_WRITE);
-	msgbufmapped = 1;
+	initmsgbuf((caddr_t)msgbufp, round_page(MSGBUFSIZE));
 
 	/*
 	 * Good {morning,afternoon,evening,night}.
@@ -792,6 +791,7 @@ dumpsys()
 	vm_offset_t maddr;	/* PA being dumped */
 	int seg;		/* RAM segment being dumped */
 	int error;		/* error code from (*dump)() */
+	extern int msgbufmapped;
 
 	/* XXX initialized here because of gcc lossage */
 	seg = 0;
diff --git a/sys/arch/mac68k/mac68k/pmap_bootstrap.c b/sys/arch/mac68k/mac68k/pmap_bootstrap.c
index 1e15d469b2c..0697dc91b18 100644
--- a/sys/arch/mac68k/mac68k/pmap_bootstrap.c
+++ b/sys/arch/mac68k/mac68k/pmap_bootstrap.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap_bootstrap.c,v 1.12 1999/04/24 06:39:41 downsj Exp $	*/
+/*	$OpenBSD: pmap_bootstrap.c,v 1.13 2000/02/22 19:27:52 deraadt Exp $	*/
 /*	$NetBSD: pmap_bootstrap.c,v 1.30 1997/01/07 07:44:01 scottr Exp $	*/
 
 /* 
@@ -103,7 +103,6 @@ extern caddr_t	ROMBase;
  *	msgbufp:	kernel message buffer
  */
 caddr_t		CADDR1, CADDR2, vmmap;
-struct msgbuf	*msgbufp;
 
 /*
  * Bootstrap the VM system.
@@ -462,8 +461,8 @@ pmap_bootstrap(nextpa, firstpa)
 		}
 	}
 	physmem = m68k_btop(avail_remaining + nextpa - firstpa);
-	avail_remaining -= m68k_round_page(sizeof(struct msgbuf));
-	high[numranges - 1] -= m68k_round_page(sizeof(struct msgbuf));
+	avail_remaining -= m68k_round_page(MSGBUFSIZE);
+	high[numranges - 1] -= m68k_round_page(MSGBUFSIZE);
 
 	/* XXX -- this doesn't look correct to me. */
 	while (high[numranges - 1] < low[numranges - 1]) {
@@ -549,7 +548,7 @@ pmap_bootstrap(nextpa, firstpa)
 		tmp_vpages[0] = va;
 		va += NBPG;
 		msgbufp = (struct msgbuf *)va;
-		va += NBPG;
+		va += MSGBUFSIZE;
 		virtual_avail = va;
 	}
 }
diff --git a/sys/arch/mvme68k/include/param.h b/sys/arch/mvme68k/include/param.h
index 0b4dc1204cf..6146d846670 100644
--- a/sys/arch/mvme68k/include/param.h
+++ b/sys/arch/mvme68k/include/param.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: param.h,v 1.7 2000/01/06 03:21:43 smurph Exp $ */
+/*	$OpenBSD: param.h,v 1.8 2000/02/22 19:27:53 deraadt Exp $ */
 
 /*
  * Copyright (c) 1988 University of Utah.
@@ -106,6 +106,8 @@
 #endif
 #endif
 
+#define MSGBUFSIZE	4096
+
 /*
  * Size of kernel malloc arena in CLBYTES-sized logical pages
  */ 
diff --git a/sys/arch/mvme68k/mvme68k/machdep.c b/sys/arch/mvme68k/mvme68k/machdep.c
index 6cde1e3e49e..101d54be691 100644
--- a/sys/arch/mvme68k/mvme68k/machdep.c
+++ b/sys/arch/mvme68k/mvme68k/machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: machdep.c,v 1.31 2000/01/06 03:21:43 smurph Exp $ */
+/*	$OpenBSD: machdep.c,v 1.32 2000/02/22 19:27:54 deraadt Exp $ */
 
 /*
  * Copyright (c) 1995 Theo de Raadt
@@ -137,7 +137,6 @@ int   bufpages = BUFPAGES;
 #else
 int   bufpages = 0;
 #endif
-int   msgbufmapped;		/* set when safe to use msgbuf */
 int   maxmem;			/* max memory per process */
 int   physmem = MAXMEM;	/* max supported memory, changes to actual */
 /*
@@ -258,12 +257,11 @@ cpu_startup()
 	 * Initialize error message buffer (at end of core).
 	 * avail_end was pre-decremented in pmap_bootstrap to compensate.
 	 */
-	for (i = 0; i < btoc(sizeof (struct msgbuf)); i++)
+	for (i = 0; i < btoc(MSGBUFSIZE); i++)
 		pmap_enter(pmap_kernel(), (vm_offset_t)msgbufp,
-					  avail_end + i * NBPG, VM_PROT_READ|VM_PROT_WRITE,
-					  TRUE, VM_PROT_READ|VM_PROT_WRITE);
-
-	msgbufmapped = 1;
+		    avail_end + i * NBPG, VM_PROT_READ|VM_PROT_WRITE,
+		    TRUE, VM_PROT_READ|VM_PROT_WRITE);
+	initmsgbuf((caddr_t)msgbufp, round_page(MSGBUFSIZE));
 
 	/*
 	 * Good {morning,afternoon,evening,night}.
@@ -802,6 +800,7 @@ dumpconf()
  */
 dumpsys()
 {
+	extern int msgbufmapped;
 
 	msgbufmapped = 0;
 	if (dumpdev == NODEV)
diff --git a/sys/arch/mvme68k/mvme68k/pmap_bootstrap.c b/sys/arch/mvme68k/mvme68k/pmap_bootstrap.c
index 9383afedf7b..fc09967e427 100644
--- a/sys/arch/mvme68k/mvme68k/pmap_bootstrap.c
+++ b/sys/arch/mvme68k/mvme68k/pmap_bootstrap.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap_bootstrap.c,v 1.4 2000/01/06 03:21:43 smurph Exp $ */
+/*	$OpenBSD: pmap_bootstrap.c,v 1.5 2000/02/22 19:27:54 deraadt Exp $ */
 
 /* 
  * Copyright (c) 1995 Theo de Raadt
@@ -103,7 +103,6 @@ extern int protection_codes[];
  *	msgbufp:	kernel message buffer
  */
 caddr_t     CADDR1, CADDR2, vmmap, ledbase;
-struct msgbuf  *msgbufp;
 #define ETHERPAGES 16
 void  *etherbuf;
 int   etherlen;
@@ -400,7 +399,7 @@ register vm_offset_t firstpa;
 	RELOC(avail_start, vm_offset_t) = nextpa;
 	RELOC(avail_end, vm_offset_t) = m68k_ptob(RELOC(maxmem, int))
 	   /* XXX allow for msgbuf */
-	   - m68k_round_page(sizeof(struct msgbuf));
+	   - m68k_round_page(MSGBUFSIZE);
 	RELOC(mem_size, vm_size_t) = m68k_ptob(RELOC(physmem, int));
 	RELOC(virtual_avail, vm_offset_t) =
 	VM_MIN_KERNEL_ADDRESS + (nextpa - firstpa);
@@ -475,7 +474,7 @@ register vm_offset_t firstpa;
 		RELOC(ledbase, caddr_t) = (caddr_t)va;
 		va += NBPG;
 		RELOC(msgbufp, struct msgbuf *) = (struct msgbuf *)va;
-		va += NBPG;
+		va += MSGBUFSIZE;
 		RELOC(virtual_avail, vm_offset_t) = va;
 	}
 }
diff --git a/sys/arch/mvme88k/include/param.h b/sys/arch/mvme88k/include/param.h
index aab7bff3cc4..20de45cd71c 100644
--- a/sys/arch/mvme88k/include/param.h
+++ b/sys/arch/mvme88k/include/param.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: param.h,v 1.10 1999/09/27 20:46:18 smurph Exp $ */
+/*	$OpenBSD: param.h,v 1.11 2000/02/22 19:27:55 deraadt Exp $ */
 /*
  * Copyright (c) 1999 Steve Murphree, Jr.
  * Copyright (c) 1988 University of Utah.
@@ -40,7 +40,7 @@
  * from: Utah $Hdr: machparam.h 1.11 89/08/14$
  *
  *	@(#)param.h	7.8 (Berkeley) 6/28/91
- *	$Id: param.h,v 1.10 1999/09/27 20:46:18 smurph Exp $
+ *	$Id: param.h,v 1.11 2000/02/22 19:27:55 deraadt Exp $
  */
 #ifndef _MACHINE_PARAM_H_
 #define _MACHINE_PARAM_H_
@@ -133,6 +133,8 @@
 #define  NKMEMCLUSTERS        (4096*1024/CLBYTES)
 #endif
 
+#define MSGBUFSIZE	4096
+
 /* pages ("clicks") to disk blocks */
 #define  ctod(x)              ((x)<<(PGSHIFT-DEV_BSHIFT))
 #define  dtoc(x)              ((x)>>(PGSHIFT-DEV_BSHIFT))
diff --git a/sys/arch/mvme88k/mvme88k/machdep.c b/sys/arch/mvme88k/mvme88k/machdep.c
index 50cf804b303..700140a76ba 100644
--- a/sys/arch/mvme88k/mvme88k/machdep.c
+++ b/sys/arch/mvme88k/mvme88k/machdep.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: machdep.c,v 1.18 1999/12/08 06:50:16 itojun Exp $	*/
+/* $OpenBSD: machdep.c,v 1.19 2000/02/22 19:27:55 deraadt Exp $	*/
 /*
  * Copyright (c) 1998, 1999 Steve Murphree, Jr.
  * Copyright (c) 1996 Nivas Madhur
@@ -157,7 +157,6 @@ volatile vm_offset_t extiova;
 int physmem;      /* available physical memory, in pages */
 int cold;         /* boot process flag */
 vm_offset_t avail_end, avail_start, avail_next;
-int msgbufmapped = 0;
 int foodebug = 0;    /* for size_memory() */
 int longformat = 1;  /* for regdump() */
 int BugWorks = 0;
@@ -461,12 +460,11 @@ cpu_startup()
     * avail_end was pre-decremented in mvme_bootstrap().
     */
 
-   for (i = 0; i < btoc(sizeof(struct msgbuf)); i++)
+   for (i = 0; i < btoc(MSGBUFSIZE); i++)
       pmap_enter(kernel_pmap, (vm_offset_t)msgbufp,
-			avail_end + i * NBPG, VM_PROT_READ|VM_PROT_WRITE,
-			VM_PROT_READ|VM_PROT_WRITE, TRUE);
-
-   msgbufmapped = 1;
+	avail_end + i * NBPG, VM_PROT_READ|VM_PROT_WRITE,
+	VM_PROT_READ|VM_PROT_WRITE, TRUE);
+   initmsgbuf((caddr_t)msgbufp, round_page(MSGBUFSIZE));
 
    printf("real mem  = %d\n", ctob(physmem));
 
@@ -1160,6 +1158,8 @@ dumpconf()
  */
 dumpsys()
 {
+   extern int msgbufmapped;
+
    msgbufmapped = 0;
    if (dumpdev == NODEV)
       return;
diff --git a/sys/arch/mvme88k/mvme88k/pmap.c b/sys/arch/mvme88k/mvme88k/pmap.c
index 08c1fb8991b..cc715bbd65e 100644
--- a/sys/arch/mvme88k/mvme88k/pmap.c
+++ b/sys/arch/mvme88k/mvme88k/pmap.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap.c,v 1.12 1999/09/27 19:13:23 smurph Exp $	*/
+/*	$OpenBSD: pmap.c,v 1.13 2000/02/22 19:27:56 deraadt Exp $	*/
 /*
  * Copyright (c) 1996 Nivas Madhur
  * All rights reserved.
@@ -1344,7 +1344,7 @@ pmap_bootstrap(vm_offset_t load_start, /* IN */
    virt = *virt_start;
 
    SYSMAP(caddr_t, vmpte , vmmap, 1);
-   SYSMAP(struct msgbuf *, msgbufmap ,msgbufp, 1);
+   SYSMAP(struct msgbuf *, msgbufmap ,msgbufp, btoc(MSGBUFSIZE));
 
    vmpte->pfn = -1;
    vmpte->dtype = DT_INVALID;
diff --git a/sys/arch/powerpc/include/param.h b/sys/arch/powerpc/include/param.h
index a243b1cbac7..429833a3db0 100644
--- a/sys/arch/powerpc/include/param.h
+++ b/sys/arch/powerpc/include/param.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: param.h,v 1.8 1999/11/28 23:20:23 rahnds Exp $	*/
+/*	$OpenBSD: param.h,v 1.9 2000/02/22 19:27:57 deraadt Exp $	*/
 /*	$NetBSD: param.h,v 1.1 1996/09/30 16:34:28 ws Exp $	*/
 
 /*-
@@ -88,6 +88,8 @@
 #endif
 #endif
 
+#define MSGBUFSIZE	NBPG
+
 /*
  * Size of kernel malloc arena in CLBYTES-sized logical pages.
  */
diff --git a/sys/arch/powerpc/powerpc/machdep.c b/sys/arch/powerpc/powerpc/machdep.c
index 482c40c6265..0f134422d85 100644
--- a/sys/arch/powerpc/powerpc/machdep.c
+++ b/sys/arch/powerpc/powerpc/machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: machdep.c,v 1.32 2000/01/22 03:51:56 rahnds Exp $	*/
+/*	$OpenBSD: machdep.c,v 1.33 2000/02/22 19:27:58 deraadt Exp $	*/
 /*	$NetBSD: machdep.c,v 1.4 1996/10/16 19:33:11 ws Exp $	*/
 
 /*
@@ -125,12 +125,6 @@ struct firmware *fw = NULL;
 
 void ofw_dbg(char *str);
 
-/*
- * We use the page just above the interrupt vector as message buffer
- */
-struct msgbuf *msgbufp = (struct msgbuf *)0x3000;
-int msgbufmapped = 1;		/* message buffer is always mapped */
-
 caddr_t allocsys __P((caddr_t));
 int power4e_get_eth_addr __P((void));
 
@@ -173,6 +167,12 @@ initppc(startkernel, endkernel, args)
 	proc0.p_addr = proc0paddr;
 	bzero(proc0.p_addr, sizeof *proc0.p_addr);
 	
+	/*
+	 * XXX We use the page just above the interrupt vector as
+	 * message buffer
+	 */
+	initmsgbuf(0x3000, MSGBUFSIZE);
+
 where = 3;
 	curpcb = &proc0paddr->u_pcb;
 	
diff --git a/sys/arch/sparc/include/param.h b/sys/arch/sparc/include/param.h
index d0480956b16..1fe8ded1d35 100644
--- a/sys/arch/sparc/include/param.h
+++ b/sys/arch/sparc/include/param.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: param.h,v 1.13 2000/02/15 16:32:41 art Exp $	*/
+/*	$OpenBSD: param.h,v 1.14 2000/02/22 19:27:59 deraadt Exp $	*/
 /*	$NetBSD: param.h,v 1.29 1997/03/10 22:50:37 pk Exp $ */
 
 /*
@@ -124,6 +124,8 @@ extern int nbpg, pgofset, pgshift;
 #endif
 #endif
 
+#define MSGBUFSIZE	4096		/* cannot be changed without great pain */
+
 /*
  * Size of kernel malloc arena in CLBYTES-sized logical pages.
  */
diff --git a/sys/arch/sparc/sparc/autoconf.c b/sys/arch/sparc/sparc/autoconf.c
index 304b8a1d539..1a6a0c4b740 100644
--- a/sys/arch/sparc/sparc/autoconf.c
+++ b/sys/arch/sparc/sparc/autoconf.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: autoconf.c,v 1.33 1999/12/08 23:49:07 deraadt Exp $	*/
+/*	$OpenBSD: autoconf.c,v 1.34 2000/02/22 19:27:59 deraadt Exp $	*/
 /*	$NetBSD: autoconf.c,v 1.73 1997/07/29 09:41:53 fair Exp $ */
 
 /*
@@ -200,19 +200,9 @@ struct om_vector *oldpvec = (struct om_vector *)PROM_BASE;
 void
 bootstrap()
 {
-	extern int msgbufmapped;
-
 #if defined(SUN4)
 	if (CPU_ISSUN4) {
 		extern void oldmon_w_cmd __P((u_long, char *));
-		extern struct msgbuf *msgbufp;
-		/*
-		 * XXX
-		 * Some boot programs mess up physical page 0, which
-		 * is where we want to put the msgbuf. There's some
-		 * room, so shift it over half a page.
-		 */
-		msgbufp = (struct msgbuf *)((caddr_t) msgbufp + 4096);
 
 		/*
 		 * XXX:
@@ -251,7 +241,6 @@ bootstrap()
 	pmap_bootstrap(cpuinfo.mmu_ncontext,
 		       cpuinfo.mmu_nregion,
 		       cpuinfo.mmu_nsegment);
-	msgbufmapped = 1;	/* enable message buffer */
 #ifdef KGDB
 	zs_kgdb_init();		/* XXX */
 #endif
diff --git a/sys/arch/sparc/sparc/locore.s b/sys/arch/sparc/sparc/locore.s
index 21bce05f5e9..6c153ab457d 100644
--- a/sys/arch/sparc/sparc/locore.s
+++ b/sys/arch/sparc/sparc/locore.s
@@ -1,4 +1,4 @@
-/*	$OpenBSD: locore.s,v 1.34 2000/02/21 17:08:36 art Exp $	*/
+/*	$OpenBSD: locore.s,v 1.35 2000/02/22 19:28:00 deraadt Exp $	*/
 /*	$NetBSD: locore.s,v 1.73 1997/09/13 20:36:48 pk Exp $	*/
 
 /*
@@ -269,8 +269,6 @@ sun4_notsup:
  * kernel space we remap it in configure() to another location and
  * invalidate the mapping at KERNBASE.
  */
-	.globl _msgbuf
-_msgbuf = KERNBASE
 
 /*
  * Each trap has room for four instructions, of which one perforce must
@@ -4674,7 +4672,7 @@ Lsw_havectx:
 #endif
 1:
 #if defined(SUN4M)
-        /*
+	/*
 	 * Flush caches that need to be flushed on context switch.
 	 * We know this is currently only necessary on the sun4m hypersparc.
 	 */
diff --git a/sys/arch/sparc/sparc/machdep.c b/sys/arch/sparc/sparc/machdep.c
index 781314d5afe..cf7a130a73c 100644
--- a/sys/arch/sparc/sparc/machdep.c
+++ b/sys/arch/sparc/sparc/machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: machdep.c,v 1.45 2000/02/21 21:05:59 art Exp $	*/
+/*	$OpenBSD: machdep.c,v 1.46 2000/02/22 19:28:01 deraadt Exp $	*/
 /*	$NetBSD: machdep.c,v 1.85 1997/09/12 08:55:02 pk Exp $ */
 
 /*
@@ -139,10 +139,6 @@ int	bufpages = 0;
 
 int	physmem;
 
-extern struct msgbuf msgbuf;
-struct	msgbuf *msgbufp = &msgbuf;
-int	msgbufmapped = 0;	/* not mapped until pmap_bootstrap */
-
 /* sysctl settable */
 int	sparc_led_blink = 0;
 
@@ -185,6 +181,13 @@ cpu_startup()
 	pmapdebug = 0;
 #endif
 
+	/*
+	 * fix message buffer mapping, note phys addr of msgbuf is 0
+	 */
+	pmap_enter(pmap_kernel(), MSGBUF_VA, 0x0, VM_PROT_READ|VM_PROT_WRITE,
+	    TRUE, VM_PROT_READ | VM_PROT_WRITE);
+	initmsgbuf((caddr_t)(MSGBUF_VA + (CPU_ISSUN4 ? 4096 : 0)), MSGBUFSIZE);
+
 	proc0.p_addr = proc0paddr;
 
 	/*
@@ -386,16 +389,6 @@ cpu_startup()
 	 */
 	bzero(proc0paddr, sizeof(struct user));
 
-	/*
-	 * fix message buffer mapping, note phys addr of msgbuf is 0
-	 */
-
-	pmap_enter(pmap_kernel(), MSGBUF_VA, 0x0, VM_PROT_READ|VM_PROT_WRITE,
-		   TRUE, VM_PROT_READ | VM_PROT_WRITE);
-	if (CPU_ISSUN4)
-		msgbufp = (struct msgbuf *)(MSGBUF_VA + 4096);
-	else
-		msgbufp = (struct msgbuf *)MSGBUF_VA;
 	pmap_redzone();
 }
 
diff --git a/sys/kern/kern_sysctl.c b/sys/kern/kern_sysctl.c
index 14f3da7c1ff..6afca527cb8 100644
--- a/sys/kern/kern_sysctl.c
+++ b/sys/kern/kern_sysctl.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kern_sysctl.c,v 1.29 1999/06/29 23:51:59 provos Exp $	*/
+/*	$OpenBSD: kern_sysctl.c,v 1.30 2000/02/22 19:28:03 deraadt Exp $	*/
 /*	$NetBSD: kern_sysctl.c,v 1.17 1996/05/20 17:49:05 mrg Exp $	*/
 
 /*-
@@ -58,6 +58,7 @@
 #include <sys/disklabel.h>
 #include <vm/vm.h>
 #include <sys/sysctl.h>
+#include <sys/msgbuf.h>
 
 #if defined(UVM)
 #include <uvm/uvm_extern.h>
@@ -349,6 +350,14 @@ kern_sysctl(name, namelen, oldp, oldlenp, newp, newlen, p)
 #else
 		return (sysctl_rdint(oldp, oldlenp, newp, 0));
 #endif
+	case KERN_MSGBUFSIZE:
+		/*
+		 * deal with cases where the message buffer has
+		 * become corrupted.
+		 */
+		if (!msgbufp || msgbufp->msg_magic != MSG_MAGIC)
+			return (ENXIO);
+		return (sysctl_rdint(oldp, oldlenp, newp, msgbufp->msg_bufs));
 	default:
 		return (EOPNOTSUPP);
 	}
diff --git a/sys/kern/subr_log.c b/sys/kern/subr_log.c
index 5d247ead19f..00eb5a93bc9 100644
--- a/sys/kern/subr_log.c
+++ b/sys/kern/subr_log.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: subr_log.c,v 1.5 1997/09/18 13:23:26 deraadt Exp $	*/
+/*	$OpenBSD: subr_log.c,v 1.6 2000/02/22 19:28:03 deraadt Exp $	*/
 /*	$NetBSD: subr_log.c,v 1.11 1996/03/30 22:24:44 christos Exp $	*/
 
 /*
@@ -65,6 +65,44 @@ struct logsoftc {
 } logsoftc;
 
 int	log_open;			/* also used in log() */
+int	msgbufmapped;			/* is the message buffer mapped */
+int	msgbufenabled;			/* is logging to the buffer enabled */
+struct	msgbuf *msgbufp;		/* the mapped buffer, itself. */
+
+#define offsetof(type, member) ((size_t)(&((type *)0)->member))
+
+void
+initmsgbuf(buf, bufsize)
+	caddr_t buf;
+	size_t bufsize;
+{
+	register struct msgbuf *mbp;
+	long new_bufs;
+
+	/* Sanity-check the given size. */
+	if (bufsize < sizeof(struct msgbuf))
+		return;
+
+	mbp = msgbufp = (struct msgbuf *)buf;
+
+	new_bufs = bufsize - offsetof(struct msgbuf, msg_bufc);
+	if ((mbp->msg_magic != MSG_MAGIC) || (mbp->msg_bufs != new_bufs) ||
+	    (mbp->msg_bufr < 0) || (mbp->msg_bufr >= mbp->msg_bufs) ||
+	    (mbp->msg_bufx < 0) || (mbp->msg_bufx >= mbp->msg_bufs)) {
+		/*
+		 * If the buffer magic number is wrong, has changed
+		 * size (which shouldn't happen often), or is
+		 * internally inconsistent, initialize it.
+		 */
+
+		bzero(buf, bufsize);
+		mbp->msg_magic = MSG_MAGIC;
+		mbp->msg_bufs = new_bufs;
+	}
+
+	/* mark it as ready for use. */
+	msgbufmapped = msgbufenabled = 1;
+}
 
 /*ARGSUSED*/
 int
@@ -73,24 +111,9 @@ logopen(dev, flags, mode, p)
 	int flags, mode;
 	struct proc *p;
 {
-	register struct msgbuf *mbp = msgbufp;
-
 	if (log_open)
 		return (EBUSY);
 	log_open = 1;
-	/*
-	 * Potential race here with putchar() but since putchar should be
-	 * called by autoconf, msg_magic should be initialized by the time
-	 * we get here.
-	 */
-	if (mbp->msg_magic != MSG_MAGIC) {
-		register int i;
-
-		mbp->msg_magic = MSG_MAGIC;
-		mbp->msg_bufx = mbp->msg_bufr = 0;
-		for (i=0; i < MSG_BSIZE; i++)
-			mbp->msg_bufc[i] = 0;
-	}
 	return (0);
 }
 
@@ -139,7 +162,7 @@ logread(dev, uio, flag)
 	while (uio->uio_resid > 0) {
 		l = mbp->msg_bufx - mbp->msg_bufr;
 		if (l < 0)
-			l = MSG_BSIZE - mbp->msg_bufr;
+			l = mbp->msg_bufs - mbp->msg_bufr;
 		l = min(l, uio->uio_resid);
 		if (l == 0)
 			break;
@@ -148,7 +171,7 @@ logread(dev, uio, flag)
 		if (error)
 			break;
 		mbp->msg_bufr += l;
-		if (mbp->msg_bufr < 0 || mbp->msg_bufr >= MSG_BSIZE)
+		if (mbp->msg_bufr < 0 || mbp->msg_bufr >= mbp->msg_bufs)
 			mbp->msg_bufr = 0;
 	}
 	return (error);
@@ -212,7 +235,7 @@ logioctl(dev, com, data, flag, p)
 		l = msgbufp->msg_bufx - msgbufp->msg_bufr;
 		splx(s);
 		if (l < 0)
-			l += MSG_BSIZE;
+			l += msgbufp->msg_bufs;
 		*(int *)data = l;
 		break;
 
diff --git a/sys/kern/subr_prf.c b/sys/kern/subr_prf.c
index 5b6eb3fd762..0ec990f67a9 100644
--- a/sys/kern/subr_prf.c
+++ b/sys/kern/subr_prf.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: subr_prf.c,v 1.26 1999/12/02 00:23:35 deraadt Exp $	*/
+/*	$OpenBSD: subr_prf.c,v 1.27 2000/02/22 19:28:04 deraadt Exp $	*/
 /*	$NetBSD: subr_prf.c,v 1.45 1997/10/24 18:14:25 chuck Exp $	*/
 
 /*-
@@ -317,12 +317,16 @@ putchar(c, flags, tp)
 	    c != '\0' && c != '\r' && c != 0177 && msgbufmapped) {
 		mbp = msgbufp;
 		if (mbp->msg_magic != MSG_MAGIC) {
-			bzero((caddr_t) mbp, sizeof(*mbp));
-			mbp->msg_magic = MSG_MAGIC;
+			/* Nothing we can do */
 		}
 		mbp->msg_bufc[mbp->msg_bufx++] = c;
-		if (mbp->msg_bufx < 0 || mbp->msg_bufx >= MSG_BSIZE)
+		if (mbp->msg_bufx < 0 || mbp->msg_bufx >= mbp->msg_bufs)
 			mbp->msg_bufx = 0;
+                /* If the buffer is full, keep the most recent data. */
+                if (mbp->msg_bufr == mbp->msg_bufx) {
+                         if (++mbp->msg_bufr >= mbp->msg_bufs)
+                                mbp->msg_bufr = 0;
+                }
 	}
 	if ((flags & TOCONS) && constty == NULL && c != '\0')
 		(*v_putc)(c);
diff --git a/sys/miscfs/kernfs/kernfs_vnops.c b/sys/miscfs/kernfs/kernfs_vnops.c
index 7af09c11138..23922ae3343 100644
--- a/sys/miscfs/kernfs/kernfs_vnops.c
+++ b/sys/miscfs/kernfs/kernfs_vnops.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kernfs_vnops.c,v 1.17 1999/11/10 23:17:39 csapuntz Exp $	*/
+/*	$OpenBSD: kernfs_vnops.c,v 1.18 2000/02/22 19:28:06 deraadt Exp $	*/
 /*	$NetBSD: kernfs_vnops.c,v 1.43 1996/03/16 23:52:47 christos Exp $	*/
 
 /*
@@ -257,12 +257,24 @@ kernfs_xread(kt, off, bufp, len)
 		extern struct msgbuf *msgbufp;
 		long n;
 
-		if (off >= MSG_BSIZE)
+		if (msgbufp == NULL || msgbufp->msg_magic != MSG_MAGIC)
+			return (ENXIO);
+
+		/*
+		 * Note that reads of /kern/msgbuf won't necessarily yield
+		 * consistent results, if the message buffer is modified
+		 * while the read is in progress.  The worst that can happen
+		 * is that incorrect data will be read.  There's no way
+		 * that this can crash the system unless the values in the
+		 * message buffer header are corrupted, but that'll cause
+		 * the system to die anyway.
+		 */
+		if (off >= msgbufp->msg_bufs)
 			return (0);
 		n = msgbufp->msg_bufx + off;
-		if (n >= MSG_BSIZE)
-			n -= MSG_BSIZE;
-		len = min(MSG_BSIZE - n, MSG_BSIZE - off);
+		if (n >= msgbufp->msg_bufs)
+			n -= msgbufp->msg_bufs;
+		len = min(msgbufp->msg_bufs - n, msgbufp->msg_bufs - off);
 		*bufp = msgbufp->msg_bufc + n;
 		return (len);
 	}
@@ -308,8 +320,8 @@ kernfs_xread(kt, off, bufp, len)
 #endif
 		break;
 #ifdef IPSEC
-        case KTT_IPSECSPI:
-                return(ipsp_kern(off, bufp, len));
+	case KTT_IPSECSPI:
+		return(ipsp_kern(off, bufp, len));
 #endif
 	default:
 		return (0);
diff --git a/sys/sys/msgbuf.h b/sys/sys/msgbuf.h
index 728a768b605..1214c4cbc8d 100644
--- a/sys/sys/msgbuf.h
+++ b/sys/sys/msgbuf.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: msgbuf.h,v 1.2 1996/03/03 12:12:03 niklas Exp $	*/
+/*	$OpenBSD: msgbuf.h,v 1.3 2000/02/22 19:28:05 deraadt Exp $	*/
 /*	$NetBSD: msgbuf.h,v 1.8 1995/03/26 20:24:27 jtc Exp $	*/
 
 /*
@@ -36,14 +36,16 @@
  *	@(#)msgbuf.h	8.1 (Berkeley) 6/2/93
  */
 
-#define	MSG_BSIZE	(4096 - 3 * sizeof(long))
 struct	msgbuf {
 #define	MSG_MAGIC	0x063061
 	long	msg_magic;
 	long	msg_bufx;		/* write pointer */
 	long	msg_bufr;		/* read pointer */
-	char	msg_bufc[MSG_BSIZE];	/* buffer */
+	long	msg_bufs;		/* real msg_bufc size (bytes) */
+	char	msg_bufc[1];		/* buffer */
 };
 #ifdef _KERNEL
 struct	msgbuf *msgbufp;
+
+void	initmsgbuf __P((caddr_t buf, size_t bufsize));
 #endif
diff --git a/sys/sys/sysctl.h b/sys/sys/sysctl.h
index 54634643e11..4f170c19ba0 100644
--- a/sys/sys/sysctl.h
+++ b/sys/sys/sysctl.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: sysctl.h,v 1.28 1999/06/29 23:52:00 provos Exp $	*/
+/*	$OpenBSD: sysctl.h,v 1.29 2000/02/22 19:28:05 deraadt Exp $	*/
 /*	$NetBSD: sysctl.h,v 1.16 1996/04/09 20:55:36 cgd Exp $	*/
 
 /*
@@ -151,7 +151,8 @@ struct ctlname {
 #define	KERN_SYSVSEM		35      /* int: SysV semaphore support */
 #define	KERN_SYSVSHM		36      /* int: SysV shared memory support */
 #define	KERN_ARND		37	/* int: random integer from arc4rnd */
-#define	KERN_MAXID		38	/* number of valid kern ids */
+#define	KERN_MSGBUFSIZE		38	/* int: size of message buffer */
+#define	KERN_MAXID		39	/* number of valid kern ids */
 
 #define CTL_KERN_NAMES { \
 	{ 0, 0 }, \
@@ -192,6 +193,7 @@ struct ctlname {
 	{ "sysvsem", CTLTYPE_INT }, \
 	{ "sysvshm", CTLTYPE_INT }, \
 	{ "arandom", CTLTYPE_INT }, \
+	{ "msgbufsize", CTLTYPE_INT }, \
 }
 
 /*
diff --git a/usr.sbin/syslogd/syslogd.c b/usr.sbin/syslogd/syslogd.c
index 5e1292eadff..13032c06ce5 100644
--- a/usr.sbin/syslogd/syslogd.c
+++ b/usr.sbin/syslogd/syslogd.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: syslogd.c,v 1.33 1999/07/06 10:07:03 millert Exp $	*/
+/*	$OpenBSD: syslogd.c,v 1.34 2000/02/22 19:28:06 deraadt Exp $	*/
 
 /*
  * Copyright (c) 1983, 1988, 1993, 1994
@@ -43,7 +43,7 @@ static char copyright[] =
 #if 0
 static char sccsid[] = "@(#)syslogd.c	8.3 (Berkeley) 4/4/94";
 #else
-static char rcsid[] = "$OpenBSD: syslogd.c,v 1.33 1999/07/06 10:07:03 millert Exp $";
+static char rcsid[] = "$OpenBSD: syslogd.c,v 1.34 2000/02/22 19:28:06 deraadt Exp $";
 #endif
 #endif /* not lint */
 
@@ -83,6 +83,7 @@ static char rcsid[] = "$OpenBSD: syslogd.c,v 1.33 1999/07/06 10:07:03 millert Ex
 #include <sys/socket.h>
 #include <sys/msgbuf.h>
 #include <sys/uio.h>
+#include <sys/sysctl.h>
 #include <sys/un.h>
 #include <sys/time.h>
 #include <sys/resource.h>
@@ -219,11 +220,11 @@ main(argc, argv)
 	int argc;
 	char *argv[];
 {
-	int ch, i, fklog, len;
+	int ch, i, fklog, len, linesize;
 	struct sockaddr_un sunx, fromunix;
 	struct sockaddr_in sin, frominet;
 	FILE *fp;
-	char *p, line[MSG_BSIZE + 1];
+	char *p, *line;
 
 	while ((ch = getopt(argc, argv, "duf:m:p:a:")) != -1)
 		switch (ch) {
@@ -274,6 +275,13 @@ main(argc, argv)
 		LocalDomain = p;
 	} else
 		LocalDomain = "";
+
+	linesize = getmsgbufsize();
+	if (linesize < MAXLINE)
+		linesize = MAXLINE;
+	linesize++;
+	line = malloc(linesize);
+
 	(void)signal(SIGTERM, die);
 	(void)signal(SIGINT, Debug ? die : SIG_IGN);
 	(void)signal(SIGQUIT, Debug ? die : SIG_IGN);
@@ -376,7 +384,7 @@ main(argc, argv)
 		}
 		/*dprintf("got a message (%d, %#x)\n", nfds, readfds);*/
 		if (fklog != -1 && FD_ISSET(fklog, &readfds)) {
-			i = read(fklog, line, sizeof(line) - 1);
+			i = read(fklog, line, linesize - 1);
 			if (i > 0) {
 				line[i] = '\0';
 				printsys(line);
@@ -1245,6 +1253,25 @@ cfline(line, f, prog)
 
 
 /*
+ * Retrieve the size of the kernel message buffer, via sysctl.
+ */
+int
+getmsgbufsize()
+{
+	int msgbufsize, mib[2];
+	size_t size;
+
+	mib[0] = CTL_KERN;
+	mib[1] = KERN_MSGBUFSIZE;
+	size = sizeof msgbufsize;
+	if (sysctl(mib, 2, &msgbufsize, &size, NULL, 0) == -1) {
+		dprintf("couldn't get kern.msgbufsize\n");
+		return (0);
+	}
+	return (msgbufsize);
+}
+
+/*
  *  Decode a symbolic name to a numeric value
  */
 int