[one-users] network boot with xen

[Vivien Bernet-Rollande]

On 19/05/2011 16:02, Michaël Van de Borne wrote:
> Can anyone tell me how to get a DHCP request sent from the booting VM?
>
Hi.

The short answer is "you can't simply do that out of the Box".

The long answer is "you can make it happen if you dig in".

I know a bit about how things work on the Xen side. Not quite sure about 
how it integrates with Open Nebula though. A good starting point is this 
: http://zhigang.org/files/docbook/xen-pxeboot.html

Basically, if you're using Xen for HVM, you may use a boot="n" 
parameter, to tell qemu-dm to perform a PXE boot. I suppose you would 
specify this as a RAW parameter in the VM template.

If you're using PV, things are slightly more complex. First you need to 
get pypxeboot (http://grid.ie/pypxeboot/), which is a pxe bootloader for 
xen. Then you need your VM to use that bootloader. Your domain config 
should contain something like :

bootloader="/usr/bin/pypxeboot"
vif=['mac=AA:00:86:e2:35:72']
bootargs=vif[0]

I'm guessing you could pass something like :
OS = [BOOTLOADER = /usr/bin/pypxeboot]
RAW = [bootarg = 'mac=AA:00:86:e2:35:72' ]

And it should work. Pure speculation though, I haven't tested it.

The even longer answer is a question : "Do you really need this ?". I'm 
not sure what you're trying to do, but it can probably be done using 
template images, contextualisation and maybe a bit of scripting. 
Virtualization is a powerful tool, offering new posibilities, and it's 
worth thinking if we really need to carry those old PXE concepts into IaaS.

-- 
Vivien Bernet-Rollande
Systems&  Networking Engineer
Alter Way Hosting