boot error mount:unknown filesystem type 'ext4'

[vinvishwa]

hi
i am trying to compile kernel 2.6.23 on Fedora 12
After fixing a few bugs (getline error, %dil ,etc) i was able to compile the kernel
made initramfs img using dracut
updated grub and then booted up the new kernel 2.6.23

but it fails to boot with following error
mount: unknown filesystem type 'ext4'

plz help
thanx,
vinvishwa

[scathefire]

perhaps the kernel was not compiled with ext4 support?

[Rubberman]

perhaps the kernel was not compiled with ext4 support?

As said, you probably didn't include ext4 support in the kernel. It was not standard/stable until the 2.6.28 kernel. It is also recommended that you get the most recent patch sets for the kernel you are installing it on.

That said, you are probably going to need to boot a live/recovery CD/DVD/USB drive with a distribution that includes ext4 support in order to access the drive to change the kernel back to fix this, unless the /boot partition is either ext2 or ext3 in which case any recent CD/DVD should work. Alternatively, your grub menu might have your previous kernel listed, in which case you should be able to boot that directly.

Good luck.

[vinvishwa]

thnx for quick replies.
ya i m able to boot back to the original kernel (2.6.31(fedora 12 default))
but i want to boot thru the new kernel(2.6.23)
so how do i add the ext 4 support to it

or
boot without ext4 support

thanx

[coopstah13]

you would have to edit fstab and not mount any partition that uses ext4, this will be a problem if it is any of the system partitions though

it will probably be very difficult to get ext4 backported in a stable state to an older kernel, is there any particular reason for running this kernel?

[Rubberman]

you would have to edit fstab and not mount any partition that uses ext4, this will be a problem if it is any of the system partitions though

it will probably be very difficult to get ext4 backported in a stable state to an older kernel, is there any particular reason for running this kernel?

Indeed. If you need to run this kernel for testing purposes, do it in a virtual machine.

[vinvishwa]

ya i m doing it in virtual machine in sun virtual box
i need this kernel as part of my acad project
coz the module i m using has been written for older kernels prior to 2.6.26

as i m not very proficient in linux
i need help tried google not useful at the moment
thanx

[Rubberman]

Ok. Do you have to use Fedora 12? FC 10 should be the correct choice for you, though you might have to do a bit of a back-step since I think it might be up to 2.6.27. But, that's a much simpler proposition I believe. Also, when you install it, you should use the ext3 file system instead of ext4. FYI, back-stepping to a pre-2.6.30 kernel has other issues as well, as there were major changes in some of the driver interfaces.

In the final analysis, install FC 10 on your virtual machine using ext3 file systems, and see what the default kernel is when you do. You might not need to back-step at all.

[Rubberman]

BTW, if you do end up building your own kernel, when you run the command "make config" at the root of the kernel souce tree, you should find some lines like this (a long way down):

The Extended 4 (ext4) filesystem (EXT4_FS) [M/n/y/?]
  Enable ext4dev compatibility (EXT4DEV_COMPAT) [Y/n/?]
  Ext4 extended attributes (EXT4_FS_XATTR) [Y/n/?]
    Ext4 POSIX Access Control Lists (EXT4_FS_POSIX_ACL) [Y/n/?]
    Ext4 Security Labels (EXT4_FS_SECURITY) [Y/n/?]

Note that this example is from my CentOS/RHEL 5.4 system, so yours might vary. In this case, ext4 support is enabled by default. If you don't run "make config" first, I don't know what the results will be.