ZFS built into kernel - mount bootfs

[furbyhaxx]

Hi everybody,
If ZFS 2.2.2 is built into the kernel, is it able to mount the dataset with the bootfs flag automatically to root /?
Or do I still need an initrd?
I only found this discussion with the associated issue #4300 which seems to be still not implemented.

[IvanVolosyuk]

I have ZFS compiled into kernel. I wasn't been able to boot kernel without initrd. It contains zpool and zfs command line utilities for mounting and it seems root=ZFS=zpool/ROOT is not recognised without initrd. It seems ZFS relies on udev to find all relevant devices as well as the cache file.

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On Thu, Feb 8, 2024, 22:27 Furby Haxx ***@***.***> wrote: Hi everybody, If ZFS 2.2.2 is built into the kernel, is it able to mount the dataset with the bootfs flag automatically to root /? Or do I still need an initrd? I only found this discussion with the associated issue #4300 <#4300> which seems to be still not implemented. — Reply to this email directly, view it on GitHub <#15865>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABXQ6HPWS2BVIZLSSSGPX3TYSSZB5AVCNFSM6AAAAABC7R56UWVHI2DSMVQWIX3LMV43ERDJONRXK43TNFXW4OZWGE4TKMJWHA> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

[rincebrain]

root=ZFS is parsed out in the initrd, I believe, yes, so that wouldn't help you here.

Conceivably you could have some zfs.import_on_boot= module parameter that triggers the "import pools on module init" logic for a specific pool name or GUID or w/e, I imagine, but I don't actually know enough about how the dataset mount process works to guess if there's something in userspace it needs for that to be sufficient on its own...

Someone could try implementing it and see.

(The other problem becomes that then you might need a lot more than just "import pool X at this location" to handle things like the systemd mount dependency parameters and all the fun that you usually use those and/or fstab for...but in the kernel.)