Booting your usb stick using Virtual Box on a Linux host
November 16th, 2012
During the development of my Linux From Scratch I was searching for a way to test the boot process using Virtual Box instead of rebooting my development computer again and again. I found some articles on how to achive this using Windows, but I use Linux on my computer. Finally I did it 
using VBoxManage internalcommands. Here comes a short howto:
1. Plug in your usb stick. The usb stick MUST contain a bootable operating system. This can be anything that boots from an usb stick.
2. Open a terminal to find out how the kernel named your usb device. (Or more accurat, its partion(s))
/dev/sdb2 on / type ext3 (rw,relatime,errors=remount-ro)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw,noexec,nosuid,nodev)
none on /sys/fs/fuse/connections type fusectl (rw)
none on /sys/kernel/debug type debugfs (rw)
none on /sys/kernel/security type securityfs (rw)
udev on /dev type devtmpfs (rw,mode=0755)
devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620)
tmpfs on /run type tmpfs (rw,noexec,nosuid,size=10%,mode=0755)
none on /run/lock type tmpfs (rw,noexec,nosuid,nodev,size=5242880)
none on /run/shm type tmpfs (rw,nosuid,nodev)
/dev/sdb5 on /tmp type ext3 (rw,relatime)
/dev/sdb7 on /usr type ext3 (rw,relatime)
/dev/sdb8 on /var type ext3 (rw,relatime)
binfmt_misc on /proc/sys/fs/binfmt_misc type binfmt_misc (rw,noexec,nosuid,nodev)
/dev/md_d0 on /home type ext3 (rw)
gvfs-fuse-daemon on /home/thorsten/.gvfs type fuse.gvfs-fuse-daemon (rw,nosuid,nodev,user=thorsten)
/dev/sdd1 on /home/thorsten/lfs type ext3 (rw)
thorsten@home:~$
Your output will look different from mine, but you should be able to find the partition(s). In my case it is /dev/sdd1.
3. Unmount all partitions of the usb stick. (This may require root privileges, depending on your system and settings). In my case it is only one partition /dev/sdd1
4. Now comes the interesting part – creating the vmdk file. To achive this I’ll use VBoxManage the console interface provided by VirtualBox. The internalcommands providing a command called createdrawvmdk. The command creates a .vmdk file using a raw disk from the host system. This file can be used later as a *harddisk* for a virtual machine. Yes!, that’s exactly what I want, the raw host disk in this case should be my usb stick.
/dev/sdd and not /dev/sdd1.internalcommands createrawvmdk \
-rawdisk /dev/sdd \
-filename my_usb_stick.vmdk
RAW host disk access VMDK file /home/thorsten/Desktop/lfs.vmdk created successfully.
root@home:/home/thorsten#
5. Create a new virtual machine that uses the my_usb_stick.vmdk as harddisk. This can be done on command line too, sure. To not confuse readers I’ll use the more regular graphical interface.
5a. Start Virtualbox
/dev/sdd, in my case)5b. Click the ‚New‘ button.
5b. Click ‚Next‘ and choose a name for the virtual machine. I used ‚Boot From Stick‘, as it can be everything that is installed on stick (and this may change).
5c. Click ‚Next‘ and select the memory size for the virtual machine. I selected 1024MB / 1GB in this example.
5d. Click ‚Next‘ and choose ‚Use existing harddisk‘
5e. Click the folder item next to the list box with images. Then select the vmdk file created before.
5f. Click ‚Open‘
5g. Click ‚Create‘ to finish the process.
6. Start the Virtual Machine. It should boot from the usb stick
Conclusion: VBoxManage internalcommands createrawvmdk is a nice tool when debugging boot problems or just run your portable usb stick linux in parallel with your home system – maybe be in order to transfer files. In addition createrawvmdk works with regular harddisks or other mediums too. So it might not ever beeing requested to boot from that media but to mount it during runtime – no problem.
You can access the help for this command by typing :
You’ll find options to in/exclude partitions from being visible to the Virtual Machine, but you’ll find the alert on end of this output too:
WARNING: This is a development tool and shall only be used to analyse
problems. It is completely unsupported and will change in
incompatible ways without warning.
I hope they will not remove this feature in upcoming versions.
cu.
Dezember 17th, 2013 at 21:55
When I attempt this I get an INT18 BOOT FAILURE. Has anyone else made this work?
(VBox 4.2.18)
Dezember 18th, 2013 at 23:22
Does VBoxManage outputs this in terminal? Which guest OS do you use?
Thorsten
März 8th, 2014 at 12:01
Thanks a ton.. for nice article..
@smerry : sudo virtualbox
März 8th, 2014 at 18:22
Nice to see that it was helpful for you
Thorsten
März 20th, 2014 at 13:44
Hi Thorsten,
Nice piece of work! It looks reasonable to me.
Unfortunately I hit – maybe – two problems:
(1) Your output of VBoxManage looks like this
„RAW host disk access VMDK file /home/thorsten/Desktop/lfs.vmdk created successfully.“
My output ays
„RAW host disk access VMDK file my_usb_stick.vmdk created successfully.“
which is probably fine as well (?).
(2) But when I assign „my_usb_stick.vmdk“ to my VM it complains about not sufficient permissions.
„chown“ to myuser:mygroup on my_usb_stick.vmdk does not help. Neither does a „chown“ on /dev/sdg (which is generally a bad thing anyway).
I’m using VirtualBox 4.3.8 on a Ubuntu host with an USB-Live-System of SliTaz as guest.
Do you have any clue about what is going wrong?
Thanks in advance and cheers!
Joerg
März 20th, 2014 at 13:49
… @Gagandeep: OK. It works if you have sudo permissions. But in my opinion it should be possible as „normal“ vboxuser als well.
Cheers!
Joerg
März 20th, 2014 at 18:50
Hi Jörg,
yeah, this are reasonable concerns. I’ll review this. Many thanks for your feedback!
Thorsten
April 26th, 2014 at 04:55
This helped a bunch, thanks! What permissions to I need to change in Debian for my sudo user to be able to use the vmdk instead of just root?
Juni 26th, 2014 at 18:28
@Joerg:
I had the same problem, and found the solution at ubuntuforums: your user needs to be member of the groups ‚vboxusers‘ and ‚disk‘. My user was a member of ‚vboxusers‘ but not of ‚disk‘.
I used ‚vigr‘, and ‚vigr -s‘ to append my username to those groups, but you can also do it using the GUI: from the dash, search ‚Users and Groups‘:
Select your username, click on ‚Advanced Settings‘.
On the ‚User Privileges‘ tab, make sure that you have
Access external storage devices automatically
Use VirtualBox virtualisation solution
Log out, log back in and you should not get the error any longer.
HTH
Januar 14th, 2015 at 01:42
all OK till I try to boot – comes up with
This kernel requires the following features not present on the CPU:
pae
Unable to boot – please use a kernel appropriate for your CPU
What is a kernel?
How can I fix this problem?
Februar 9th, 2015 at 15:41
Hi,
which operating system do you have installed on your usb stick? What ist your host operating system? (The system where Virtual Box is installed on)
Thorsten
Mai 9th, 2016 at 21:24
I did not want to run Virtualbox as root.
I did not want my user to be of the disk group, having full permissions to all disks.
So here is what I got to work:
Find out what sd the memory stick is. In the following instrucions it’s sdc
Unmount memory Stick
su
chmod 666 /dev/sdc1
chmod 666 /dev/sdc
VBoxManage internalcommands createrawvmdk -filename usb.vmdk -rawdisk /dev/sdc
chmod 777 usb.vmdk
chmod 666 /dev/sdc
Attach usb.vmdk virtualbox machine
chmod 666 /dev/sdc
Start virtualbox machine
After done, reset sdc1 permission for security:
chmod 660 /dev/sdc1
In the above you can see that I had to reset the permissions for the memory stick a few times, because it would get set back to root each time.
Wayne Sallee
Wayne@WayneSallee.com