Hello! I’ve reworked this patch series a bit, but now I’m stuck on this: Danny Milosavljevic skribis: > ERROR: In procedure network-interface-flags: > In procedure network-interface-flags: No such device When than happens, our modprobe gets called with the “netdev-eth0” alias, which it cannot handle, leading to this error. By explicitly loading “virtio_net” and sleeping a bit, we get past that point, but fail later on: --8<---------------cut here---------------start------------->8--- loading '/gnu/store/n2zvdxp25kvg7wy5xr1y5n9r4502fw80-linux-vm-loader'... environment variable `PATH' set to `/gnu/store/vxl918zb9brnrgaipzsykpy3mzcafvcr-qemu-minimal-2.11.1/bin:/gnu/store/lvkaf3xlvy57bvap51xlzb209ilbkgcv-parted-3.2/sbin:/gnu/store/nm305rpb2mvridkyj4l3636nc9ql4lf9-e2fsprogs-1.43.6/bin:/gnu/store/nm305rpb2mvridkyj4l3636nc9ql4lf9-e2fsprogs-1.43.6/sbin:/gnu/store/0sq2nflm42x0znkv44add0gk82khkcb6-dosfstools-4.1/sbin:/gnu/store/0hl513mnpkhszm2hjai2w9cxmpxs0vgq-sed-4.4/bin:/gnu/store/1h44pkgdd7n6s3i2vjh54awsvfmc219j-grep-3.1/bin:/gnu/store/kgzvfby2ggi1xawsh5vjh4s93qk2dp9k-coreutils-8.28/bin:/gnu/store/k7r2m2wgj8x8jjhccwjsiimp0dlzxb7i-findutils-4.6.0/bin:/gnu/store/ahxc89r6npzf2bbl8yg5vdjicskzzjf3-gawk-4.1.4/bin' creating partition table with 2 partitions (20.0 MiB, 40.0 MiB)... Warning: The resulting partition is not properly aligned for best performance. creating ext4 partition... mke2fs 1.43.6 (29-Aug-2017) ext2fs_check_if_mount: Can't check if filesystem is mounted due to missing mtab file while determining whether /dev/vda1 is mounted. Creating filesystem with 20480 1k blocks and 5136 inodes Filesystem UUID: 81a538e9-3efe-406b-bf67-fa153fa3c6a6 Superblock backups stored on blocks: 8193 Allocating group tables: done Writing inode tables: done Creating journal (1024 blocks): done Writing superblocks and filesystem accounting information: done [ 3.190801] EXT4-fs (vda1): mounted filesystem with ordered data mode. Opts: (null) populating... clearing file timestamps... creating FAT partition... mkfs.fat 4.1 (2017-01-24) [ 3.235493] FAT-fs (vda2): IO charset iso8859-1 not found ERROR: In procedure mount: In procedure mount: Invalid argument --8<---------------cut here---------------end--------------->8--- Here the nls_iso8859-1 module doesn’t get loaded and modprobe isn’t even invoked, although my understanding is that it should (per ‘load_nls’ in nls_base.c in the kernel, called from vfat/inode.c). Similarly, it seems that virtio_blk has to be loaded explicitly: is not reported by ‘needed-modules’ (i.e., not listed in /sys/…/modalias), nor do we get a modprobe query for it. All in all on-demand loading seems more complicated that it seemed. What are we missing here? Ludo’.