我正在尝试使用guestmount它来检查/修改 FreeBSD .qcow2 图像（我在这里看到了几个答案，但我发现没有任何东西可以真正解决我的问题）。
我在 Debian Sid 下工作。
显然图像被正确识别：
mcon@cinderella:~/projects/LXD$ guestfish -a /home/mcon/VirtualBox\ VMs/FreeBSD-13.2-RELEASE-amd64.qcow2
Welcome to guestfish, the guest filesystem shell for
editing virtual machine filesystems and disk images.
Type: ‘help’ for help on commands
‘man’ to read the manual
‘quit’ to quit the shell
><fs> run
><fs> list-filesystems
/dev/sda1: unknown
/dev/sda2: vfat
/dev/sda3: unknown
/dev/sda4: ufs
><fs>
但挂载严重失败：
mcon@cinderella:~/projects/LXD$ guestmount -a /home/mcon/VirtualBox\ VMs/FreeBSD-13.2-RELEASE-amd64.qcow2 -m /dev/sda4 --rw -o subtype=ufs2 /mnt
libguestfs: error: mount_options: mount exited with status 32: mount: /sysroot: wrong fs type, bad option, bad superblock on /dev/sda4, missing codepage or helper program, or other error.
dmesg(1) may have more information after failed mount system call.
guestmount: ‘/dev/sda4’ could not be mounted.
guestmount: Did you mean to mount one of these filesystems?
guestmount: /dev/sda1 (unknown)
guestmount: /dev/sda2 (vfat)
guestmount: /dev/sda3 (unknown)
guestmount: /dev/sda4 (ufs)
我做了一些变化，也尝试从源代码重新编译整个包，但结果是相同的。
我缺少什么？
注意：我无法使用qemu-nbdandsudo mount -t ufs -o ufstype=ufs2 /dev/nbd0p4 /mnt/因为ufs.ko内核模块是在没有写入支持的情况下编译的。