Date: Tue, 11 Jul 2000 11:36:49 +0200 (CEST) From: Udo Erdelhoff <ue@nathan.ruhr.de> To: FreeBSD-gnats-submit@freebsd.org Subject: docs/19848: dumpon(8) needs to be updated [patch] Message-ID: <200007110936.LAA16205@nathan.ruhr.de>
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>Number: 19848
>Category: docs
>Synopsis: dumpon(8) needs to be updated [patch included]
>Confidential: no
>Severity: non-critical
>Priority: medium
>Responsible: freebsd-doc
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: doc-bug
>Submitter-Id: current-users
>Arrival-Date: Tue Jul 11 03:00:02 PDT 2000
>Closed-Date:
>Last-Modified:
>Originator: Udo Erdelhoff
>Release: FreeBSD 5.0-CURRENT i386
>Organization:
>Environment:
FreeBSD 5.0-current as of 08-JUL-2000
src/sbin/dumpon/dumpon.8 v1.13
>Description:
The bugs section of dumpon(8) states:
Dumpon currently allows only devices with minor number 1 to be used as
dump devices.
This is obviously no longer true. Various messages on the mailing lists
show that people have been dumping to /dev/da0s1b (minor 0x20001) with
good effect.
The bugs section does not mention that setting DUMPDEV in rc.conf causes
dumpon to be called during the transition from single-user to multi-user.
This means that it's close to impossible to capture dumps caused by
problem during boot. There was a discussion on -current about this
problem in March 2000 (see revision 1.12 of this file). The problem
has not been resolved yet (AFAIK), so bugs should warn about it.
Additionally, a part of the notes section should be changed.
Old version:
One of the system swap devices is usually chosen as the dump device, as
swap devices are the most likely to have the required space at dump time.
New version:
One of the system swap devices should be used as the dump device. Devices
used for regular filesystems will probably lack sufficent space to store the
dump.
[And that's the polite version - I was tempted to write to something
to the effect of "using anything but a swap device is suicidal"]
>How-To-Repeat:
man 8 dumpon
dumpon /dev/any-swap-device
put DUMPEV=above-device in rc.conf
panic the system, reboot
=> core is saved in /var/crash
>Fix:
The patch implements the changes outlined above. The changes should be
MFCed to RELENG_4 before 4.1-RELEASE.
Index: dumpon.8
===================================================================
RCS file: /home/ncvs/src/sbin/dumpon/dumpon.8,v
retrieving revision 1.13
diff -u -r1.13 dumpon.8
--- dumpon.8 2000/03/28 15:54:32 1.13
+++ dumpon.8 2000/07/11 09:10:57
@@ -68,8 +68,9 @@
.Nm
to be verbose about its activity.
.Sh NOTES
-One of the system swap devices is usually chosen as the dump device, as
-swap devices are the most likely to have the required space at dump time.
+One of the system swap devices should be used as the dump device. Devices
+used for regular filesystems will probably lack sufficent space to store the
+dump.
.Pp
The
.Nm
@@ -106,9 +107,13 @@
Because the filesystem layer is already dead by the time a crash dump
is taken, it is not possible to send crash dumps directly to a file.
.Pp
-.Nm Dumpon
-currently allows only devices with minor number 1 to be used as dump
-devices.
+Since
+.Nm dumpon
+is called from
+.Pa /etc/rc ,
+system panics during kernel initialisation or single-user mode will NOT
+cause a dump. Currently, there is no safe or reliable way to enforce
+the creation of dumps in these cases.
.Sh HISTORY
The
.Nm
>Release-Note:
>Audit-Trail:
>Unformatted:
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