Re: Users can provide their own kernels? (Was: Re: [Xen-users] Basic Question)

[Mark Williamson <mark.williamson@xxxxxxxxxxxx>]

> > Yes.  You just stick a grub.conf / menu.lst in the usual place and should
> > Just Work.
>
> Eh, maybe I did not get it completly: You mean I create a config-file using
> disk = [ 'file:/...' ]
> without a kernel= command? And it boots the first sectors like the BIOS
> would do?

To be honest I've not used it so I'm not exactly sure.  Something like that 
should work, but note:
a) PyGrub looks for the grub.conf / menu.lst on the first guest disk (i.e. 
first in the list).  Make sure that file exists on that device.
b) it doesn't boot the first sectors of the disk, PyGrub is part of Xend.  
Therefore you don't need to install a bootloader in the guest, it'll just 
work.

> > We're also working an another bootloader approach based on kexec but the
> > effect will be the same.
>
> Hm can you elaborate that?

PyGrub runs as part of Xend, in dom0.  It accesses guest filesystems without 
mounting them (for security reasons) in order to parse the grub config and 
load the kernel.

Kexec allows a kernel to act as a bootloader and jump into a new kernel 
directly.  It's slated for inclusion in Linux 2.6.13.  This approach would 
boot a special "bootloader" kernel in the guest and run the bootloader in the 
domU instead of dom0.  This is even more paranoid in security terms ;-) and 
also makes it easier to support weird filesystems in the guest.

For most people it will not matter much which approach is used.  I'm 
implementing kexec anyway because it's a cool hack.

More details in my other post ;-)

Cheers,
Mark

> > Cheers,
> > Mark
> >
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