The important fixes for qemu are in comment 8: --- FWIW the following 2 commits in qemu master resolve the issue for qemu-img. http://git.qemu.org/?p=qemu.git;a=commit;h=38c4d0aea3e1264c86e282d99560330adf2b6e25 http://git.qemu.org/?p=qemu.git;a=commit;h=7c15903789953ead14a417882657d52dc0c19a24 If possible they should be back ported to trusty and utopic. You'll also need something like: http://git.qemu.org/?p=qemu.git;a=commit;h=4f11aa8a40351b28c0e67c7276e0003b38cc46ac before my 2 patches. ---