Don't use the block device to read crashdumps, if possible.

sbin/savecore/savecore.c

@@ -1,4 +1,4 @@
-/*	$NetBSD: savecore.c,v 1.71 2007/11/12 16:04:55 pooka Exp $	*/
+/*	$NetBSD: savecore.c,v 1.72 2008/01/15 14:26:42 ad Exp $	*/
 
 /*-
  * Copyright (c) 1986, 1992, 1993
@@ -39,7 +39,7 @@ __COPYRIGHT("@(#) Copyright (c) 1986, 1992, 1993\n\
 #if 0
 static char sccsid[] = "@(#)savecore.c	8.5 (Berkeley) 4/28/95";
 #else
-__RCSID("$NetBSD: savecore.c,v 1.71 2007/11/12 16:04:55 pooka Exp $");
+__RCSID("$NetBSD: savecore.c,v 1.72 2008/01/15 14:26:42 ad Exp $");
 #endif
 #endif /* not lint */
 
@@ -93,11 +93,13 @@ struct nlist current_nl[] = {	/* Namelist for currently running system. */
 	{ .n_name = "_panicend" },
 #define	X_MSGBUF	10
 	{ .n_name = "_msgbufp" },
+#define	X_DUMPCDEV	11
+	{ .n_name = "_dumpcdev" },
 	{ .n_name = NULL },
 };
-int cursyms[] = { X_DUMPDEV, X_DUMPLO, X_VERSION, X_DUMPMAG, -1 };
+int cursyms[] = { X_DUMPDEV, X_DUMPLO, X_VERSION, X_DUMPMAG, X_DUMPCDEV, -1 };
-int dumpsyms[] = { X_TIME_SECOND, X_TIME, X_DUMPSIZE, X_VERSION, X_PANICSTR, X_DUMPMAG,
+int dumpsyms[] = { X_TIME_SECOND, X_TIME, X_DUMPSIZE, X_VERSION, X_PANICSTR,
-    -1 };
+    X_DUMPMAG, -1 };
 
 struct nlist dump_nl[] = {	/* Name list for dumped system. */
 	{ .n_name = "_dumpdev" },	/* Entries MUST be the same as */
@@ -111,6 +113,7 @@ struct nlist dump_nl[] = {	/* Name list for dumped system. */
 	{ .n_name = "_panicstart" },
 	{ .n_name = "_panicend" },
 	{ .n_name = "_msgbufp" },
+	{ .n_name = "_dumpcdev" },
 	{ .n_name = NULL },
 };
 
@@ -124,8 +127,9 @@ const char	*kernel;		/* name of used kernel */
 char	*dirname;			/* directory to save dumps in */
 char	*ddname;			/* name of dump device */
 dev_t	dumpdev;			/* dump device */
-int	dumpfd;				/* read/write descriptor on block dev */
+dev_t	dumpcdev = NODEV;		/* dump device (char equivalent) */
-kvm_t	*kd_dump;			/* kvm descriptor on block dev	*/
+int	dumpfd;				/* read/write descriptor on dev */
+kvm_t	*kd_dump;			/* kvm descriptor on dev	*/
 time_t	now;				/* current date */
 char	panic_mesg[1024];
 long	panicstr;
@@ -266,14 +270,20 @@ kmem_setup(void)
 		syslog(LOG_ERR, "%s: kvm_nlist: %s", kernel,
 		    kvm_geterr(kd_kern));
 	
-	for (i = 0; cursyms[i] != -1; i++)
+	for (i = 0; cursyms[i] != -1; i++) {
-		if (current_nl[cursyms[i]].n_value == 0 &&
+		if (current_nl[cursyms[i]].n_value != 0)
-			cursyms[i] != X_TIME_SECOND &&
+			continue;
-		        cursyms[i] != X_TIME) {
+		switch (cursyms[i]) {
+		case X_TIME_SECOND:
+		case X_TIME:
+		case X_DUMPCDEV:
+			break;
+		default:
 			syslog(LOG_ERR, "%s: %s not in namelist",
 			    kernel, current_nl[cursyms[i]].n_name);
 			exit(1);
 		}
+	}
 
 	if (KREAD(kd_kern, current_nl[X_DUMPDEV].n_value, &dumpdev) != 0) {
 		if (verbose)
@@ -312,7 +322,17 @@ kmem_setup(void)
 	    sizeof(vers));
 	vers[sizeof(vers) - 1] = '\0';
 
-	ddname = find_dev(dumpdev, S_IFBLK);
+	if (current_nl[X_DUMPCDEV].n_value != 0) {
+		if (KREAD(kd_kern, current_nl[X_DUMPCDEV].n_value,
+		    &dumpcdev) != 0) {
+			if (verbose)
+				syslog(LOG_WARNING, "kvm_read: %s",
+			            kvm_geterr(kd_kern));
+			exit(1);
+		}
+		ddname = find_dev(dumpcdev, S_IFCHR);
+	} else
+		ddname = find_dev(dumpdev, S_IFBLK);
 	dumpfd = Open(ddname, O_RDWR);
 
 	kd_dump = kvm_openfiles(kernel, ddname, NULL, O_RDWR, errbuf);
@@ -489,7 +509,7 @@ void
 clear_dump(void)
 {
 	if (kvm_dump_inval(kd_dump) == -1)
-		syslog(LOG_ERR, "%s: kvm_clear_dump: %s", ddname,
+		syslog(LOG_ERR, "%s: kvm_dump_inval: %s", ddname,
 		    kvm_geterr(kd_dump));
 
 }
@@ -544,10 +564,16 @@ err1:			syslog(LOG_WARNING, "%s: %m", path);
 		}
 	}
 
-	/* Open the raw device. */
+	if (dumpcdev == NODEV) {
-	rawp = rawname(ddname);
+		/* Open the raw device. */
-	if ((ifd = open(rawp, O_RDONLY)) == -1) {
+		rawp = rawname(ddname);
-		syslog(LOG_WARNING, "%s: %m; using block device", rawp);
+		if ((ifd = open(rawp, O_RDONLY)) == -1) {
+			syslog(LOG_WARNING, "%s: %m; using block device",
+			    rawp);
+			ifd = dumpfd;
+		}
+	} else {
+		rawp = ddname;
 		ifd = dumpfd;
 	}
 
@@ -587,7 +613,8 @@ err2:			syslog(LOG_WARNING,
 			exit(1);
 		}
 	}
-	(void)close(ifd);
+	if (dumpcdev == NODEV)
+		(void)close(ifd);
 	(void)fclose(fp);
 
 	/* Copy the kernel. */

sys/kern/kern_subr.c

@@ -1,4 +1,4 @@
-/*	$NetBSD: kern_subr.c,v 1.174 2008/01/10 16:29:17 ad Exp $	*/
+/*	$NetBSD: kern_subr.c,v 1.175 2008/01/15 14:26:42 ad Exp $	*/
 
 /*-
  * Copyright (c) 1997, 1998, 1999, 2002, 2007, 2006 The NetBSD Foundation, Inc.
@@ -86,7 +86,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_subr.c,v 1.174 2008/01/10 16:29:17 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_subr.c,v 1.175 2008/01/15 14:26:42 ad Exp $");
 
 #include "opt_ddb.h"
 #include "opt_md.h"
@@ -142,6 +142,8 @@ MALLOC_DEFINE(M_IOV, "iov", "large iov's");
 int tftproot_dhcpboot(struct device *);
 #endif
 
+dev_t	dumpcdev;	/* for savecore */
+
 void
 uio_setup_sysspace(struct uio *uio)
 {
@@ -1099,6 +1101,7 @@ setroot(struct device *bootdv, int bootpartition)
 		}
 	}
 
+	dumpcdev = devsw_blk2chr(dumpdev);
 	aprint_normal(" dumps on %s", dumpdv->dv_xname);
 	if (DEV_USES_PARTITIONS(dumpdv))
 		aprint_normal("%c", DISKPART(dumpdev) + 'a');
@@ -1107,6 +1110,7 @@ setroot(struct device *bootdv, int bootpartition)
 
  nodumpdev:
 	dumpdev = NODEV;
+	dumpcdev = NODEV;
 	aprint_normal("\n");
 }
 

sys/sys/systm.h

@@ -1,4 +1,4 @@
-/*	$NetBSD: systm.h,v 1.211 2008/01/14 22:47:22 yamt Exp $	*/
+/*	$NetBSD: systm.h,v 1.212 2008/01/15 14:26:41 ad Exp $	*/
 
 /*-
  * Copyright (c) 1982, 1988, 1991, 1993
@@ -81,6 +81,7 @@ extern int maxmem;		/* max memory per process */
 extern int physmem;		/* physical memory */
 
 extern dev_t dumpdev;		/* dump device */
+extern dev_t dumpcdev;		/* dump device (character equivalent) */
 extern long dumplo;		/* offset into dumpdev */
 extern int dumpsize;		/* size of dump in pages */
 extern const char *dumpspec;	/* how dump device was specified */