Kernel Panic - not syncing: VFS: Unable to mount root fs after new kernel compile

Question

So I've been at this for a while and have been poking around for an answer for a few days, and figure it's about time to ask for help. I am running Ubuntu 10.10 in VMWare Fusion, and have downloaded a copy of the 3.2 kernel and built it with all default settings. When I try to boot into the new kernel after a call to make install, I get the following message:

[    1.581916] Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
[    1.582260] Pid: 1, comm: swapper/0 Not tainted 3.2.4 #1
[    1.582444] Call Trace:
[    1.582552]  [<ffffffff815e7447>] panic+0x91/0x1a7
[    1.582666]  [<ffffffff815e75c5>] ? printk+0x68/0x6b
[    1.582799]  [<ffffffff81ad2152>] mount_block_root+0x1ea/0x29e
[    1.582929]  [<ffffffff81ad225c>] mount_root+0x56/0x5a
[    1.583047]  [<ffffffff81ad23d0>] prepare_namespace+0x170/0x1a9
[    1.583178]  [<ffffffff81ad16f7>] kernel_init+0x144/0x153
[    1.583304]  [<ffffffff815f45f4>] kernel_thread_helper+0x4/0x10
[    1.583436]  [<ffffffff81ad15b3>] ? parse_early_options+0x20/0x20
[    1.583570]  [<ffffffff815f45f0>] ? gs_change+0x13/0x13

Which used to appear on every reboot. I found that if I changed the VM's harddrive type, I could get GRUB to boot at least, but the message above comes up if I try to load the newly compiled kernel. The old kernel works as before. I have checked and I have compiled in support for ext4, which is the fs my root is running. I have also tried generating an initrd file with a call to "sudo update-initramfs -c -k 3.2.4", but to no avail.

The compilation, I think, was pretty standard:

make menuconfig
make
make modules_install
make install
update-grub
reboot

Were the general steps. In terms of options, I basically took the default on everything. In case it's pertinent, my fstab looks like this:

proc            /proc           proc    nodev,noexec,nosuid 0       0
#UUID=c75eddd9-f4fa-49be-927b-8c2da7074135 /               ext4    errors=remount-ro 0       1                                                                                                                                                                                                                                                  
/dev/sda1                                  /               ext4    defaults          0       1
#UUID=5bc6915e-fdfa-479a-885f-ea03cb14f9cd none            swap    sw              0       0                                                                                                                                                                                                                                                    
/dev/sda5                                  none            swap    sw              0       0
/dev/fd0        /media/floppy0  auto    rw,user,noauto,exec,utf8 0       0

Where I've tried it with both UUID's and /dev/sd* notation. Any help or advice would be much appreciated, as it's gotten quite frustrating.

Thank you.

Solution 1

You forgot to build your initrd that goes with the kernel. Run update-initramfs -c -k kernelversion and then update-grub to find it and add it to the grub menu.

Solution 2

Did you built in all the drivers required to mount the root partition? I mean, the I/O controller driver, the filesystem driver, and so on?

The error means what it means, the kernel is unable to mount the root filesystem.

I don't recall what exactly should unknown block be, but I guess that means it is lacking the I/O controller driver.

Please note that the drivers have to be built into the kernel, modules won't work (as you need to mount the filesystem to get access to the modules).

Comments

[fromClouds]

Well that was simple enough. This was all it took. I actually ran update-initramfs -c -k previously, but didn't think to re-update grub afterward. Thanks much.

[Luka]

Sorry to comment for such an old post, but I have/had same problem. I just updated my fresh install of centos with yum update and then i can't boot it... When i click something before automatic start i have 2 centos to choose, i am assuming it's 2 centos kernels... and it works with second option. what should i do? thanks. Update grub maybe?