Kernel panic - not syncing: VFS: Unable to mount root fs on unkown-block(3,2)

Rhatlinux · 02-11-2006, 11:24 PM

I am attempting to compile my own Linux 2.6.15-4 kernel on an IBM Thinkpad T23 laptop. I do not know what I am doing wrong. I am only using the ext2 filesystem. I am receiving this error message:

Code:

Kernel panic - not syncing: VFS: Unable to mount root fs on unkown-block(3,2)

Maybe I did not select an option that I should have. I made the required changes to /boot/grub/menu.lst. Here is my .config file: http://pastebin.com/550643

btmiller · 02-12-2006, 12:02 AM

It looks like you don't have any filesystems but ext2 configured. You need to compile support for your root filesystem into te kernel (or as a module and then load it via an initrd -- see mkinitrd for more details).

Rhatlinux · 02-12-2006, 12:26 AM

I am using ext2 for my root filesystem.

schatoor · 02-12-2006, 06:26 AM

Quote:

I am using ext2 for my root filesystem.

Yes, we got that. But are you sure you have compiled ext2 support in to the kernel and NOT as an module? Unless this module is available through an initrd file, you will get an kernel panic.

duffmckagan · 02-12-2006, 06:35 AM

So, recompile your kernel (just make menuconfig) and check you have compiled support for all the file systems you are using.

<M> in front of an option means that it is "Modularized".

So make sure that you have a <*> in front of the option for File Systems.

Rhatlinux · 02-12-2006, 08:25 AM

Code:

#
#
#
# File systems
#
#
#
CONFIG_EXT2_FS=y
#
CONFIG_EXT2_FS_XATTR=y
#
CONFIG_EXT2_FS_POSIX_ACL=y
#
CONFIG_EXT2_FS_SECURITY=y
#
# CONFIG_EXT2_FS_XIP is not set
#
# CONFIG_EXT3_FS is not set
#
# CONFIG_JBD is not set
#
CONFIG_FS_MBCACHE=y
#
# CONFIG_REISERFS_FS is not set
#
# CONFIG_JFS_FS is not set
#
CONFIG_FS_POSIX_ACL=y
#
# CONFIG_XFS_FS is not set
#
# CONFIG_MINIX_FS is not set
#
# CONFIG_ROMFS_FS is not set
#
CONFIG_INOTIFY=y
#
CONFIG_QUOTA=y
#
CONFIG_QFMT_V1=m
#
CONFIG_QFMT_V2=m
#
CONFIG_QUOTACTL=y
#
CONFIG_DNOTIFY=y
#
# CONFIG_AUTOFS_FS is not set
#
CONFIG_AUTOFS4_FS=y
#
CONFIG_FUSE_FS=m

The ext2 is set to be built-in to the kernel.

Rhatlinux · 02-12-2006, 11:48 AM

I put a * for every option in the filesystem section and recompiled my kernel. I am still receiving a kernel panic.

duffmckagan · 02-13-2006, 02:04 AM

Did you copy over the new kernel to your boot directory?

If you haven't done it, you are still booting from your old kernel.

Milesss · 02-13-2006, 07:40 AM

Maybe your kernel looks for root partition in wrong place? Have you tried to pass "root=/dev/hd**" option to kernel at boot?

guysoft · 02-13-2006, 02:21 PM

while i was setting up a RAID array i found out that after kernel 2.6.12 you must use mkinitramfs and not mkinitrd. otherwise you get kernel panic.

Milesss · 02-13-2006, 06:44 PM

I think I have figured out what can cause this. There may be two reasons:
1. You haven't turned on support for IDE in your kernel.
or
2. You haven't selected Dos MBR support under File Systems->Partiton Types->Advance Partition selection (I don't remeber exact name of option).

I've had similar problem with 2.6.15.3 kernel and selecting these options to compile into kernel solved it.

Rhatlinux · 02-14-2006, 11:53 AM

Quote:

I think I have figured out what can cause this. There may be two reasons:
1. You haven't turned on support for IDE in your kernel.
or
2. You haven't selected Dos MBR support under File Systems->Partiton Types->Advance Partition selection (I don't remeber exact name of option).

I've had similar problem with 2.6.15.3 kernel and selecting these options to compile into kernel solved it.

I compiled the kernel about 10 times since I posted. You were absolutely right. I had IDE support complied, but I did not have an option compiled that was related to ATA2. Then I could not enable DMA using "hdparm -d1 /dev/hda." I needed to enable the "Pentium IIX IDE chipset support" for DMA to work. I also enabled the "Use DMA when avaliable" so I did not have to manually enable it using hdparm. I did not have to enable anything under "Partition Types."

duffmckagan · 02-14-2006, 12:04 PM

Knowing your computer inside out is the most important consideration required for *successful* Kernel Compilations.