Description of problem: $ virt-make-fs --type=fat . /tmp/test.img 'mkfs' (create filesystem) operation failed. Instead of 'fat', try 'vfat' (long filenames) or 'msdos' (short filenames). mkfs: fat: /dev/sda: mkfs.fat: Device partition expected, not making filesystem on entire device '/dev/sda' (use -I to override) at /usr/bin/virt-make-fs line 508, <PIPE> line 1. ...propagated at /usr/bin/virt-make-fs line 518, <PIPE> line 1. It looks as if the 'mkfs' command requires -I when the filesystem type is fat/vfat/etc to force it to work. Version-Release number of selected component (if applicable): libguestfs 1.25.8 How reproducible: 100% Steps to Reproduce: See command above.
Patch posted: https://www.redhat.com/archives/libguestfs/2013-December/msg00058.html
This is fixed upstream: https://github.com/libguestfs/libguestfs/commit/b1210152217b35f52f204a1d92ee988ca713949c The fix should appear in libguestfs >= 1.25.14 and >= 1.24.3.