id = 2840
title = "After converting the Windows 10 system disk from qcow2 to LUKS format with pre-allocated space, the system fails to boot"
state = "opened"
created_at = "2025-02-25T09:14:57.193Z"
closed_at = "n/a"
labels = ["Storage"]
url = "https://gitlab.com/qemu-project/qemu/-/issues/2840"
host-os = "linux"
host-arch = "x86"
qemu-version = "QEMU 9.2.50"
guest-os = "windows10"
guest-arch = "x86"
description = """When converting a qcow2 file containing an installed Windows 10 system to LUKS format, using the --target-is-zero parameter in the conversion command prevents the LUKS image from shrinking. However, when attempting to boot the virtual machine with the converted LUKS file, VNC login shows a black screen, and the system fails to start. If the conversion is performed without the --target-is-zero parameter, the system boots up normally"""
reproduce = """1. create a luks image
qemu-img create -f qcow2 --object secret,data=123,id=sec0 -o preallocation=full,encrypt.format=luks,encrypt.key-secret=sec0 encry_ok.qcow2 50G
2.
qemu-img convert -t none -T none --object secret,id=sec0,data=123 -f qcow2 ./windows10.qcow2  -n -m 1 --target-image-opts driver=qcow2,encrypt.key-secret=sec0,file.filename=encry_ok.qcow2 --target-is-zero

windows10.qcow2 container windows20 system and  it can be booted
3.
./qemu-system-x86_64  -accel kvm -cpu SandyBridge  -object memory-backend-memfd,id=mem1,size=4G -machine memory-backend=mem1  -smp 4  -object secret,id=sec0,data=123,format=raw -drive if=none,driver=qcow2,file.filename=/sdc1/luzhipeng/encry_ok.qcow2,encrypt.key-secret=sec0,id=drive0,cache=none  -device virtio-blk,drive=drive0,bootindex=1  -monitor stdio -vnc :4

4. vnc shows a black screen, and the system fails to start

5. if use convert command:
qemu-img convert -t none -T none --object secret,id=sec0,data=123 -f qcow2 ./windows10.qcow2  -n -m 1 --target-image-opts driver=qcow2,encrypt.key-secret=sec0,file.filename=encry_ok.qcow2

6. the windows10 system can start successful"""
additional = """"""