Unable to mount root fs on unknown-block(202,3)

[Denys Vlasenko]

On Friday 12 October 2007 07:23, Rajeev Bansal wrote:
> Hello All,
>  
> I am trying to build a custom initrd using the busybox. In my initrd I 
> have modified the /sbin/init to a init script which I am mentioning below,
> 
> #!/bin/sh -e
> # Set up filesystem as root and pivot into it.
...

It's nice that you are using busybox, but not relevant to
your current problem. Problem happens before execution
reaches your custom /sbin/init. Read below.

> I burnt an ISO image in a CD with this initrd and Kernel image, when I 
> tries to boot using the CD I am getting the following logs on the kernel 
> and in last my Kernel gives the Panic.
> 
> ISOLINUX 3.51 2007-06-10  Copyright (C) 1994-2007 H. Peter Anvin
> boot:
> Loading /install.386/vmlinuz.................................
> Loading 
> /install.386/initrd.gz..................................................
> ................................................................................
> ...................................................................
> Ready.
> Linux version 2.6.21-1.3194.fc7 
> (kojibuilder at xenbuilder4.fedora.phx.redhat.com)
...
> NET: Registered protocol family 17
> Using IPI No-Shortcut mode
>   Magic number: 11:520:13
> drivers/rtc/hctosys.c: unable to open rtc device (rtc0)
> md: Autodetecting RAID arrays.
> md: autorun ...
> md: ... autorun DONE.
> VFS: Cannot open root device "<NULL>" or unknown-block(202,3)
> Please append a correct "root=" boot option
> Kernel panic - not syncing: VFS: Unable to mount root fs on 
> unknown-block(202,3)
> 
> Please let me know what I am missing in the configuration.

Kernel didn't use your initrd. There is only one message
related to it in kernel log:

"Freeing initrd memory: 12436k freed"

IIRC, in order to mount initrd image as a root fs, you need to pass
root=/dev/ram parameter to kernel. Currently you are not doing this:

"Kernel command line: vga=normal initrd=/install.386/initrd.gz console=ttyS0,9600 BOOT_IMAGE=/install.386/vmlinuz"

--
vda