Query about changes to GRUB 2 for booting a physical machine using a virtual image

Query about changes to GRUB 2 for booting a physical machine using a virtual image

[Swapnesh Chaubal]

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Hello,

My name is Swapnesh Chaubal. I am a graduate student in Computer Science at
Clemson University. We are working on a project in which we would like to
boot physical machines using virtual images stored on a server (via a
network boot). I came across a tool called VBoot that manages to do this.
It works perfectly in conjunction with the windows bootloader, however, when
I try it on linux (ext2/3 file system)  and make changes to the grub as it
suggests on their website, it fails to load.

The following entry needs to be added in GRUB2 (according to their website).

menuentry "VHD Mint 9, Linux 2.6.32-21-generic" {
	linux (hd0,1)/mint-9/vmlinuz-2.6.32-21-generic root=/dev/sda1
vloop=/mint-9/mint-9-gnome-i386.vhd vlooppart=p1 quiet splash
	initrd (hd0,1)/mint-9/initrd.img-2.6.32-21-generic
}

The thing which has got me perplexed is, how do they manage to make GRUB2
understand the 'vloop' and 'vlooppart' command? Is there a way that this can
be achieved? (They do have a GRUB module called vboot.mod in thier grub
folder).

Thank you,
Swapnesh

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Re: Query about changes to GRUB 2 for booting a physical machine using a virtual image

[Colin Watson]

On Thu, Mar 24, 2011 at 03:58:08PM -0400, Swapnesh Chaubal wrote:
> The following entry needs to be added in GRUB2 (according to their website).
> 
> menuentry "VHD Mint 9, Linux 2.6.32-21-generic" {
> 	linux (hd0,1)/mint-9/vmlinuz-2.6.32-21-generic root=/dev/sda1
> vloop=/mint-9/mint-9-gnome-i386.vhd vlooppart=p1 quiet splash
> 	initrd (hd0,1)/mint-9/initrd.img-2.6.32-21-generic
> }
> 
> The thing which has got me perplexed is, how do they manage to make GRUB2
> understand the 'vloop' and 'vlooppart' command?

Those are not GRUB commands; they're parameters to the Linux kernel,
which GRUB just passes through as a string.  (The line-wrapping above
makes me wonder whether you made sure to put "vloop=..." on the same
line as "linux".)

> Is there a way that this can be achieved? (They do have a GRUB module
> called vboot.mod in thier grub folder).

It would be interesting to know what that does; I imagine that it's a
disk driver that causes the virtual disk image to be visible as a disk
in GRUB.  You probably need to invoke it somehow before the menuentry is
executed.

Unfortunately, as far as I can tell from
http://www.vmlite.com/index.php?option=com_content&view=article&id=51&Itemid=148,
they do not provide source code for their modifications to GRUB; all I
can find is
http://www.vmlite.com/index.php?option=com_content&view=article&id=65&Itemid=175,
which says "Coming soon, you can download our modified open source GRUB2
and VirtualBox source code that VBoot have used."  I don't think that's
good enough since they're distributing the binaries now, and are
therefore bound by the terms of the GNU General Public License.

I will contact them and ask that they remedy this situation.

-- 
Colin Watson                                       [cjwatson@ubuntu.com]

Re: Query about changes to GRUB 2 for booting a physical machine using a virtual image

[Phillip Susi]

You may be interested in this:

http://etherboot.org/wiki/start

There is a very nice video of a conference google hosted on the subject
of network booting there.  It's a bit long, but worth the watch.