1QA output created by 114 2Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 backing_file=TEST_DIR/t.IMGFMT.orig backing_fmt=raw 3Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=67108864 4qemu-img: Use of backing file requires explicit backing format 5Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=IMGFMT 6Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=IMGFMT 7image: TEST_DIR/t.IMGFMT 8file format: IMGFMT 9virtual size: 64 MiB (67108864 bytes) 10cluster_size: 65536 11backing file: TEST_DIR/t.IMGFMT.base 12backing file format: foo 13qemu-io: can't open device TEST_DIR/t.qcow2: Could not open backing file: Unknown driver 'foo' 14no file open, try 'help open' 15read 4096/4096 bytes at offset 0 164 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) 17qemu-img: Could not change the backing file to 'TEST_DIR/t.qcow2.base': backing format must be specified 18read 4096/4096 bytes at offset 0 194 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) 20*** done 21