Date: Mon, 20 Jul 1998 15:13:26 -0700 (PDT) From: dwhite@resnet.uoregon.edu To: freebsd-gnats-submit@FreeBSD.ORG Subject: docs/7336: Add FAQ entry for ''Can't mount root'' panic Message-ID: <199807202213.PAA25257@hub.freebsd.org>
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>Number: 7336
>Category: docs
>Synopsis: Add FAQ entry for ''Can't mount root'' panic
>Confidential: no
>Severity: non-critical
>Priority: high
>Responsible: freebsd-doc
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: doc-bug
>Submitter-Id: current-users
>Arrival-Date: Mon Jul 20 15:20:00 PDT 1998
>Last-Modified:
>Originator: Doug White
>Organization:
UO CIS
>Release: N/A
>Environment:
N/A
>Description:
Patch to add the FAQ question that should have been there years ago.
It's amazing what deadlines do to you :)
Could someone please expedite this it'll make it into 2.2.7? I realize
it's last second but ...
>How-To-Repeat:
>Fix:
Index: install.sgml
===================================================================
RCS file: /usr/local/cvs/doc/FAQ/install.sgml,v
retrieving revision 1.6
diff -u -r1.6 install.sgml
--- install.sgml 1998/07/13 07:48:07 1.6
+++ install.sgml 1998/07/20 22:07:43
@@ -490,5 +490,50 @@
After the system is installed you can reconnect the drive. Hopefully
this will be fixed in a later release.
+ <sect1>
+ <heading>I get a ``panic: cant mount root'' error when rebooting the system
after installation.</heading>
+
+ <p>This error comes from confusion between the boot block's and the
+ kernel's understanding of the disk devices. The error usually
+ manifests on two-disk IDE systems, with the hard disks arranged as the
+ master or single device on separate IDE controllers, with FreeBSD
+ installed on the secondary IDE controller. The boot blocks think
+ the system is installed on wd1 (the second BIOS disk) while the kernel
+ assigns the first disk on the secondary controller device wd2. After
+ the device probing, the kernel tries to mount what the boot blocks
+ think is the boot disk, wd1, while it is really wd2, and fails.
+
+ <p>To fix the problem, do one of the following:
+
+ <enum>
+ <item>At the Boot: prompt, enter
+ <tt>1:wd(0,a)/kernel</tt> and press Enter. If the system starts, then
+ run the command
+<verb>
+echo "1:wd(0,a)/kernel" > /boot.config
+</verb>
+ to make it the default boot string.
+ <item>Move the FreeBSD disk onto the primary IDE controller, so the
+ hard disks are consecutive.
+ <item><url url="../handbook/kernelconfig.html" name="Rebuild your kernel,"
>
+ modify the wd configuration lines to read:
+
+<verb>
+controller wdc0 at isa? port "IO_WD1" bio irq 14 vector wdintr
+disk wd0 at wdc0 drive 0
+# disk wd1 at wdc0 drive 1 # comment out this line
+
+controller wdc1 at isa? port "IO_WD2" bio irq 15 vector wdintr
+disk wd1 at wdc1 drive 0 # change from wd2 to wd1
+disk wd2 at wdc1 drive 1 # change from wd3 to wd2
+</verb>
+
+ Install the new kernel.
+ If you moved your disks and wish to restore the previous
+ configuration, replace the disks in the desired configuration and reboot.
+ Your system should boot successfully.
+
+ </enum>
+
</sect>
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