qemu-img cannot create fixed vhdx When trying to create a fixed vhdx image, qemu-img fails with the following error: qemu-img: test.vhdx: Could not create image: Cannot allocate memory This happens because of a incorrect check in vhdx.c Works for me on 07e2863d0271ac6c05206d8ce9e4f4c39b25d3ea: $ uname -a Linux 3.16.2-200.fc20.x86_64 #1 SMP Mon Sep 8 11:54:45 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux $ ./qemu-img create -f vhdx -o subformat=fixed test.vhdx 10G Formatting 'test.vhdx', fmt=vhdx size=10737418240 log_size=1048576 block_size=0 subformat='fixed' Please include the command-line needed to reproduce this bug. You also mentioned an "incorrect check in vhdx.c". What exactly is wrong? If you have a patch, please send it to