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Re: [Xen-devel] Re: Xen bootloader

To: "Mark Williamson" <mark.williamson@xxxxxxxxxxxx>
Subject: Re: [Xen-devel] Re: Xen bootloader
From: "Jacob Gorm Hansen" <jacobg@xxxxxxx>
Date: Fri, 14 Jul 2006 13:45:14 -0700
Cc: Richard Miller <9xen@xxxxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx, rminnich@xxxxxxxx
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On 7/14/06, Mark Williamson <mark.williamson@xxxxxxxxxxxx> wrote:
> > let's not forget Plan 9, eh? Would this approach support plan 9?
> Sure, as long as the xen binary load file format is still supported.
> We can load out of a FAT partition.

AFAIK it ought to be a case of just making sure the kexec tools can load the
Xenified plan9 kernel - we could always patch them if necessary, I guess.

It seems like the right approach would be to mimic the bios rather
than put yet another Linux kernel in the trusted base. Supposedly this
new bootloader we are talking about would be part of the TCB, and so
shold be small, trustworthy, and stable. Relying on the ability to
patch things later on just to support new formats is going in the
wrong direction IMHO.

I'd opt for porting grub. I already have a format-neutral two-stage
domU bootloader which boots Linux from the ramdisk as well as unrolls
checkpoints, and writing it was not that hard. The only thing that has
kept me from submitting it as a patch* it is the issue of
hypercall-page initialisation, but my emails about this to the list
have gone unanswered lately. Sure it needs block or network drivers,
but starting out with something small rather than the inherently
bloated and buggy Linux code seems a much better idea.

Oh well, at least people seem to have discovered that dom0 domain
building is a dead-end :-)


* The source is here:
http://www.distlab.dk/hg/index.cgi/xen-evilman.hg -- in the
extras/cstrap directory.

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