From c9bc6f3a9abaf17422a7cefaad26b3680094b5f6 Mon Sep 17 00:00:00 2001
From: simonb <simonb@NetBSD.org>
Date: Wed, 2 Jul 2003 07:05:29 +0000
Subject: [PATCH] Allow the dmesg command to show the last N bytes of the
 kernel message buffer.

---
 sys/ddb/db_xxx.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/sys/ddb/db_xxx.c b/sys/ddb/db_xxx.c
index 81870d4fc79a..e5b6e7b370a5 100644
--- a/sys/ddb/db_xxx.c
+++ b/sys/ddb/db_xxx.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: db_xxx.c,v 1.24 2003/06/29 22:29:55 fvdl Exp $	*/
+/*	$NetBSD: db_xxx.c,v 1.25 2003/07/02 07:05:29 simonb Exp $	*/
 
 /*
  * Copyright (c) 1982, 1986, 1989, 1991, 1993
@@ -43,7 +43,7 @@
 #include "opt_kgdb.h"
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: db_xxx.c,v 1.24 2003/06/29 22:29:55 fvdl Exp $");
+__KERNEL_RCSID(0, "$NetBSD: db_xxx.c,v 1.25 2003/07/02 07:05:29 simonb Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -234,6 +234,7 @@ void
 db_dmesg(db_expr_t addr, int haddr, db_expr_t count, char *modif)
 {
 	struct kern_msgbuf *mbp;
+	db_expr_t print;
 	int ch, newl, skip, i;
 	char *p, *bufdata;
 
@@ -245,10 +246,17 @@ db_dmesg(db_expr_t addr, int haddr, db_expr_t count, char *modif)
 	mbp = msgbufp;
 	bufdata = &mbp->msg_bufc[0];
 
+	if (haddr && addr < mbp->msg_bufs)
+		print = addr;
+	else
+		print = mbp->msg_bufs;
+
 	for (newl = skip = i = 0, p = bufdata + mbp->msg_bufx;
 	    i < mbp->msg_bufs; i++, p++) {
 		if (p == bufdata + mbp->msg_bufs)
 			p = bufdata;
+		if (i < mbp->msg_bufs - print)
+			continue;
 		ch = *p;
 		/* Skip "\n<.*>" syslog sequences. */
 		if (skip) {