Other Root on hammer2

[Annalesa]

It's in a bhyve guest:
I installed hammer2 by pkg install hammer2.
Then
kldload hammer2
newfs_hammer2 /dev/nda1
mount -t hammer -o hflags=0 /dev/nda1 /mnt
and installed FreeBSD-15.1-RELEASE on /mnt.
I use a separate /boot because the efi loader dose not support hammer2.
It's my /boot/loader.conf
root@anna:~ # cat /mnt/boot/loader.conf
zfs_load="YES"
hammer2_load="YES"
vfs.root.mountfrom="hammer2:/dev/nda1"
vfs.root.mountfrom.options="hflags=0"
But other PFS like /dev/nda1@AAA cannot be mounted in the mountroot phase in this way.
And I'm trying to find a workable method
root@anna:~ # hammer2 stat /
PATH ncp data-use inode-use comp check quota
/ 0 469.22MB 10598 lz4:default xxhash64
root@anna:~ # mount
/dev/nda1 on / (hammer2, local)
devfs on /dev (devfs)
zroot/var/log on /var/log (zfs, local, noatime, noexec, nosuid, nfsv4acls)
zroot/ROOT/test on /mnt (zfs, local, noatime, nfsv4acls)

 

[covacat]

i tried it but it insta panics on write
newfs, mount, pfs-create works but a write will cause a panic
i tried on 14.5 on arm64. im not sure what causes the problem version or arch

 

[T-Daemon]

But other PFS like /dev/nda1@AAA cannot be mounted in the mountroot phase in this way.
And I'm trying to find a workable method

Why not mount PFSs via /etc/fstab as described in the DragonFly BSD handbook, chapter Manual Installation with an Extended HAMMER2 Disk Layout? Scroll down to "Describe all mounts in fstab:".

 

[covacat]

if i disable lz4 with hammer2(8) works a bit better like it not panics but hangs on umount
seems broken on arm because upgrading to 15.1 did not change anything to the better