device: 0.789 mistranslation: 0.726 other: 0.707 semantic: 0.705 network: 0.626 vnc: 0.615 socket: 0.540 boot: 0.523 instruction: 0.516 graphic: 0.429 KVM: 0.123 assembly: 0.108 UEFI firmware can't write to "fake" FAT hard disk Using the Tianocore OVMF UEFI firmware, a UEFI application cannot write to the emulated fat disk (-hda fat:rw:path/here). A file will get created or written, but will be corrupted. Looking through old bug tickets ... When reporting issues, please provide proper information on the versions that you were using (QEMU, OVMF, ...) and complete information about which command line parameters you used to start QEMU. Out of scope; please see my (independent, more recent) replies here: [edk2-devel] OVMF/QEMU shell based unit tests and writing to a virtual disk https://edk2.groups.io/g/devel/message/66655 https://edk2.groups.io/g/devel/message/66656 (alternative links: https://www.redhat.com/archives/edk2-devel-archive/2020-October/msg00877.html https://www.redhat.com/archives/edk2-devel-archive/2020-October/msg00878.html )