Re: [Xen-users] xen in in the stock linux kernel...

[Tom Brown <xensource.com@xxxxxxxxxxxxxxxxxxx>]

On Fri, 19 Oct 2007, Mark Williamson wrote:

> The XenLinux in the XenSource repositority is currently a separate codebase
> from the mainline Linux Xen support (although code flows between the two) and
> it does have support for x86_64, which I assume you've tried?
no. I just ran into a situation where I needed a modern linux kernel so I 
could get a more current CIFS implimentation... moving the cifs directory 
between linux versions does not work :(  This didn't start as a XEN study, 
so I haven't poked deeply at the XEN options... if I was that much of a 
keener I probably wouldn't still be running close to a dozen 3.0.x xen 
hosts... :) :(
> > I poked around on the wiki and in google, but I can't find
> > anything about getting a stock linux kernel to run... It seems
> > you want to copy the vmlinux file out of the top of the kernel
> > source tree, strip it, and gzip it ... that APPEARS to get the
> > right format of file that the xen tools will try to load... but
> > at that point I'm hosed... with the xen_guest message.
> Yeah.  It's not possible to boot bzImage kernels directly under Xen at all;
> that requires an update of the bzImage format, which has to be made without
> breaking buggy bootloaders - so that part of the effort is going slow.
>
> The vmlinux from the source tree should load on its own; stripping it and
> gzipping it to get a small vmlinuz helps keep the size down a lot though!
At this point I don't care much, if vmlinux is good enough, that should be 
fine. I couldn't find _any_ docs on this process ... I was just trying to 
match what the domU and dom0 kernels looked like.
> What Xen were you running this on?  I've had a mainline kernel boot
> successfully on the Xen 3.0.3 shipped with CentOS / RHEL 5.  Are you sure
> that paravirt_ops support *and* the specific Xen support were both compiled
> into the kernel?
AFAIK, You can't get xen support without the paravirt options... and I did 
look at the system-map for my kernel, and it was full of xen symbols, it 
just didn't have __xen_guest in it ... Hhmm, a quick grep of the the 
linux.2.6.23.1 tree only shows xen_guest in 
include/xen/interface/elfnote.h ... and event that is only in the 
comments...
from xm info...

xen_major              : 3
xen_minor              : 0
xen_extra              : .2-2
xen_caps               : xen-3.0-x86_32

That's just what's on the i386 box... From where I sit, it looks like my 
issues are a consequence of not keeping up to date.
can you tell me more about "32-bit PAE compatibility mode on an x64 Xen 
host"? I'd never heard of that. I've also trying to get hvm working on one 
of the x86_64 machines ... I had a corrupted rpm database that slowed 
things down a bit, and since my overall goal is win2003 <-> Linux file 
access I've spent a fair bit of the day on other topics.
The 3.0.2 i386 box is at a state where I have both remote power and remote 
serial console control... (just tested)... it's a drbd secondary so I 
don't really want to trash it, but rebooting it isn't a big deal as long 
as I'm darn sure it's going to come back.
THANKS for the info, you've given me more than a few things to look into.

-Tom

> Cheers,
> Mrak
Gotta like it when people typo their own names :)

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