Gentoo root-on-lvm boot problem

[leonchik1976]

When i use genkernel it boots fine, but when i use manual kernel (but with the same kernel confiration + manual initrams), i have error "Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block".
I also noticed that with manual kernel, volume groups and pg are not detected at all. i use EXT4 on boot and root, also checked that dm-mod is included. any suggestion, please?

[MikeTbob]

Hello and Welcome
I don't think Gentoo kernel includes ext4 support by default so you need to compile that into your kernel and not as a module.

[leonchik1976]

EXT4 is built in kernel. Device-mapper i tried to compile as separate module and with kernel

[MikeTbob]

Try this link....for LVM.
Gentoo Linux Documentation -- Gentoo LVM2 installation

[leonchik1976]

yep, i use it for building initramfs, also another few guides, problem still exist

[MikeTbob]

Can you post your grub.conf or menu.lst file for us to look at? Also post the output of

fdisk -l

One thing I noticed awhile back is that when I installed Gentoo, it named my partitions hda1, hda 2 and so on, but after I got it installed everything changed to sda1, sda2. Could this be your problem?

[Jonathan183]

One thing I noticed awhile back is that when I installed Gentoo, it named my partitions hda1, hda 2 and so on, but after I got it installed everything changed to sda1, sda2. Could this be your problem?

use uuid to identify correct partitions, at one point when I was running a manually configured kernel and also genkernel one reported hda and the other reported sda ... by using
root=/dev/disk/by-uuid/.... in /boot/grub/grub.conf and
/dev/disk/by-uuid/... in /etc/fstab I was able to boot from either kernel

If this does not cure the issue it will at least allow you to rule this out as the issue ...