`No filesystem could mount root` when following README

[pchaigno]

I built the base images as per the README, but I'm failing to boot them:

$ go run ./cmd/lvh run --image _data/images/k8s.qcow2 --kernel bpf-next-20250310.013008/boot/vmlinuz-6.14.0-rc3-gf28214603dc6
[...]
[    1.083892] List of all partitions:
[    1.085998] fe00         8388608 vda 
[    1.086006]  driver: virtio_blk
[    1.089747] No filesystem could mount root, tried: 
[    1.089750]  ext3
[    1.092772]  ext2
[    1.093895]  ext4
[    1.094954]  vfat
[    1.096147]  msdos
[    1.097327]  iso9660
[    1.098653]  fuseblk
[    1.099974] 
[    1.102318] Kernel panic - not syncing: VFS: Unable to mount root fs on "/dev/vda" or unknown-block(254,0)
[    1.106796] CPU: 1 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.14.0-rc3-gf28214603dc6 #1
[    1.109395] Hardware name: QEMU Ubuntu 24.04 PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
[    1.112236] Call Trace:
[    1.112934]  <TASK>
[    1.113561]  panic+0x32b/0x390
[    1.114416]  mount_root_generic+0x254/0x310
[    1.115604]  prepare_namespace+0x64/0x280
[    1.116601]  kernel_init_freeable+0x28b/0x2d0
[    1.117628]  ? __pfx_kernel_init+0x10/0x10
[    1.118513]  kernel_init+0x1a/0x1c0
[    1.119225]  ret_from_fork+0x34/0x50
[    1.120000]  ? __pfx_kernel_init+0x10/0x10
[    1.120877]  ret_from_fork_asm+0x1a/0x30
[    1.121608]  </TASK>
[    1.122418] Kernel Offset: disabled