zfs-9999 + genkernel-3.5.0.5/9999 - block device mypool/ds is not a valid block device

[bunder2015]

could not boot latest head (as of 09/27) with newer genkernel (which should have the fix for the libgcc_s bug). pool gets imported but doesn't get mounted anywhere.

Importing ZFS pool mypool
Import of mypool succeeded
Determining block device

Block device mypool/ds is not a valid block device
Could not find the root block device in . 
Please specify a new value (blah blah blah)

[GregorKopka]

This looks like gentoo and from my experience is very likely related to a wrong grub configuration or a zpool.cache file that made it into the initramfs.

Did your ZFS root before (re)emerging zfs-9999, if so with what version?

[bunder2015]

Yes, this is on gentoo. Boot works just fine on an older git version from June-ish (0.6.5-329_g5c27b29 is what is reported from "modinfo zfs").

[GregorKopka]

Working entry in my grub.cfg:

menuentry 'Gentoo GNU/Linux' --class gentoo --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-simple-4512c8b427c4d8ff' {
        load_video
        if [ "x$grub_platform" = xefi ]; then
                set gfxpayload=keep
        fi
        insmod gzio
        insmod part_gpt
        insmod part_gpt
        insmod zfs
        echo    'Loading Linux x86_64-4.4.6-gentoo ...'
        linux   /ROOT/gentoo@/boot/kernel-genkernel-x86_64-4.4.6-gentoo root=ZFS=boot/ROOT/gentoo ro
        echo    'Loading initial ramdisk ...'
        initrd  /ROOT/gentoo@/boot/initramfs-genkernel-x86_64-4.4.6-gentoo
}

From memory what I have done to get it booting:

Removed this block

                set root='hd0,gpt1'
                if [ x$feature_platform_search_hint = xy ]; then
                  search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt1 --hint-efi=hd0,gpt1 --hint-baremetal=ahci0,gpt1  --hint-bios=hd3,gpt1 --hint-efi=hd3,gpt1 --hint-baremetal=ahci3,gpt1  4512c8b427c4d8ff
                else
                  search --no-floppy --fs-uuid --set=root 4512c8b427c4d8ff
                fi

from the grub menu entry since it seems to interfere in locating root

Also quite important was to rename /etc/zfs/zpool.cache prior to creating the initramfs with

genkernel all --clean --no-mountboot --zfs --bootloader=grub2 --callback="emerge @module-rebuild spl zfs-kmod zfs"

(extra --callback list to have zfs-kmod recompile). My guess is the zpool.cache in the initrd fucked it up pretty good, since every time I forgot to move it away I had to recover.

Hope this helps.

[markwright]

I think it is a Gentoo genkernel bug, so I raised a bug report and proposed a patch for you to please try here:

https://bugs.gentoo.org/show_bug.cgi?id=597154

If you agree please continue the discussion in the above Gentoo bug report, thanks.

[GregorKopka]

Gentoo patch looks reasonable: a ZFS filesystem isn't a block device by definition.
As it dosn't seem to be a bug in ZoL I think you can close this one here.

[behlendorf]

Agreed, I'm closing this.