I'm attempting to set up a ZFS root system and am using genkernel. I've got the zfs-0.8.0-rc3 build for ZFS installed which has the proper initrd scripts to do encrypted datasets. I installed ZFS in the chroot environment and installed genkernel-next, ran genkernel --bootloader=grub --zfs all and after all was built, rebooted. I was then prompted with initramfs exiting that it couldn't load the ZFS modules with the error "Invalid Module Format"
The original system I used for the install was the Ubuntu server CD, because it lets me install a build environment to compile ZFS in order to create/import the pool with version 0.8.0-rc3.
This is basically how I did this (from the Ubuntu install CD), these more more notes than actual step by step instructions:
#Setup build environment for ZFS
sudo apt-get install build-essential autoconf libtool gawk alien fakeroot zlib1g-dev uuid-dev libattr1-dev libblkid-dev libselinux-dev libudev-dev parted lsscsi ksh libssl-dev libelf-dev linux-headers-$(uname -r)
#Copy modules to tmp and do a bind, this is to allow writing to /lib/modules which is needed for the install of the ZFS modules for the initial boot env
cp -R /lib/modules /tmp/
mount --bind /tmp/modules /lib/modules
#Get specifically 0.8.0-rc3, which incorporates dataset encryption
git clone -b 'zfs-0.8.0-rc3' https://github.com/zfsonlinux/zfs
make -s -j$(nproc)
I then did the appropriate mounts and chroot and from there I installed the 0.8.0-rc3 ZFS package (keywords updates required, since it's not stable), grub, genkernel.
I plan to tar this installation up and move it to a server host when I'm done, it's in a VM for now.
Errors also include "spl: disagrees about version of symbol module_layout" and "modprobe: can't load module spl extra/spl/spl.ko): invalid module format"
While I await someone who might have some answers, I'm working on building a custom Funtoo LiveCD with the ZFS modules built in. I'm using the guide from https://www.funtoo.org/Make_your_own_LiveCD_using_Funtoo_Linux
During my build of the LiveCD, I came across the "emerge -C sys-kernel/debian-sources-lts" command and it's been ages since I worked with Gentoo/Funtoo, but it reminded me that maybe I need to adjust/check my kernel sources (I had deleted the kernels/initrd images from the debain sources in /boot, but I didn't unmerge the packages) - so I removed them and am now installing gentoo-sources, to then re-compile zfs and re-run genkernel against this. Hopefully this proves fruitful.
Ok, with gentoo-sources and a clean /usr/src with proper linux symlink and a re-compile/reinstall of zfs and a fresh run of genkernel --bootloader=grub --zfs all - I am now missing the ZFS modules (in initramfs), I run modprobe zfs and I get module zfs not found in modules.dep when I try modprobe zfs (and I searched /lib/modules and found no zfs modules). Grrr.... maybe this is because it's been so long since I used Gentoo/Funtoo, maybe I'm missing something basic and stupid.