Dual boot access windows partition through virtual box

Question

So I have a dual-boot system running windows 10 and Ubuntu 16.04. I have separated them by partitioning.

I have certain programs and files on the windows partition that I need from time to time and it's a hassle to shut down Ubuntu and reboot into windows, especially if i have terminals and programs open with states I don't want to close and re-open.

So my question is: Is it possible to boot the windows partition in a VBox while using Ubuntu? And if it is, how do I do this?

Answer 1

Actually, I did not know, but it seems to be possible to do this in VirtualBox as well:

You'll first want to create a virtual machine within the VirtualBox GUI. Choose all options like normal, but when asked about the virtual hard drive, select Do not add a virtual hard drive.

Issue fdisk to list the partitions and find the Windows partition:

sudo fdisk -l

Assuming /dev/sda

VBoxManage internalcommands createrawvmdk -filename "</path/to/file>.vmdk" -rawdisk /dev/sda1

WARNING: do not attempt to boot your host OS or mount its partition in the VM or bad things will happen!

Answer 2

It is indeed possible with KVM (reproduced below). You will need an UEFI implementation which you can download and there are a bunch of options you need to set for qemu. The following should work on Intel chipsets with sound. You probably want to test without sound and networking first.

WARNING: do not attempt to boot your host OS or its drive in the VM or bad things will happen!

sudo qemu-system-x86_64 --enable-kvm -cpu host -m 2048 -smp 3 -mem-path /dev/hugepages \
-display sdl -vga qxl \
-device qemu-xhci,id=xhci \
-device virtio-tablet,wheel-axis=true \
-soundhw hda \
-netdev user,id=vmnic,smb=/temp \
-device virtio-net,netdev=vmnic \
-drive file=/usr/share/ovmf/x64/OVMF_CODE.fd,if=pflash,format=raw,unit=0,readonly=on \
-drive file=$HOME/.config/qemu-windows.nvram,if=pflash,format=raw,unit=1 \
-drive file=/dev/sdb,index=0,media=disk,driver=raw \
-cdrom /opt/UefiShell.iso

For now I use sudo, because QEMU needs to access raw partitions from /dev/sdb. The other, better way would be assigning a group to /dev/sdb, setting up proper group permissions and adding me to that group.

-m 2048 -smp 3 says to allocate 2GB of RAM for the guest and use 3 CPU cores

-mem-path /dev/hugepages is better described in Arch wiki.

-display sdl -vga qxl Use SDL for rendering and window management in the host and QXL GPU device in the guest (there are QXL drivers for Windows).

-device qemu-xhci,id=xhci Enable USB3 support by emulating an XHCI controller

-device virtio-tablet,wheel-axis=true Emulate a tablet pointing device with mouse scroll support

-soundhw hda Emulate Intel HD Audio

netdev stuff Is for setting up network interface

-drive file=/usr/share/ovmf/x64/OVMF_CODE.fd,if=pflash,format=raw,unit=0,readonly=on This is a very important part. It loads OVMF UEFI firmware read-only as the first Flash device. This firmware implements a UEFI bios and allows running UEFI Shell or booting .efi bootloader for Windows (bootmgfw.efi). This OVMF can be downloaded directly from the OVMF project repo or if you are using Arch Linux, just install ovmf package.

-drive file=$HOME/.config/qemu-windows.nvram,if=pflash,format=raw,unit=1 this loads a read-write NVRam flash image as the second virtual flash chip. OVMF firmware uses this to store UEFI variables, .efi boot order, etc. The default image can be copied from the OVMF setup (at /usr/share/ovmf/x64/OVMF_VARS.fd in ovmf Arch linux package). It must be a writable copy.

-drive file=/dev/sdb,index=0,media=disk,driver=raw Attaches my raw sdb block device to the virtual machine. That is used as a HDD for the guest, it has Windows pre-installed there together with EFI partition.

-cdrom /opt/UefiShell.iso UEFI shell iso as a CDROM. Before OVMF nvram is properly configured to boot Windows by default, this will result in booting into the EFI shell which allows to run .efi executables manually. Windows can be run by just navigating into the EFI partition and running the Windows efi loader – blkX:\EFI\Microsoft\Boot\bootmgfw.efi.

I don’t know how to force Windows to write UEFI boot order. There doesn’t seem to be a tool like efibootmgr on Windows. :D Windows would set the UEFI boot order up randomly during some Windows Updates (mostly when you don’t want it to touch your EFI setup). It eventually set the EFI config up for me itself quite quickly. But if it fails, you can try pressing ESC during TianoCore EFI boot to get to boot menu. Or you can always boot Linux using the -cdrom command and use efibootmgr to force the OVMF to boot the Windows loader entry for this virtual machine by default. Usage of the efibootmgr command is out of scope of this article and can be found in many online resources elsewhere.