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

[Mark Williamson <mark.williamson@xxxxxxxxxxxx>]

> > You can grab it from Linus' git tree, or you can probably download a
> > snapshot of that tree.  Remember that you need to set your architecture
> > to be PPro or newer, otherwise the Xen option won't show up - that
> > confused me for some time a couple of days ago ;-)
>
> Finally got around to trying this... but it looks like the kernel config
> options for XEN (and PARAVIRT) only exist in the arch/i386 tree :( ...
> I've been trying to use x86_64 for the year or more, but it sure seems to
> be an uphill path :(

Yep, the mainline support is x86_64 only for the moment (though it ought to 
run in 32-bit PAE compatibility mode on an x64 Xen host).

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?

> So, I've found one small machine of mine that is an i386 build, but I
> can't seem to get the new kernel packaged up correctly... or maybe this
> only works with newer hypervisors? None of the boxes I currently have
> access to are running anything more current than 3.0.4
>
> ERROR: Kernel image does not have a a.out9 header.
> ERROR: Unrecognized image format
> ERROR: Error constructing guest OS
>
> and after monkeying around:
>
> ERROR: Not a Xen-ELF image: '__xen_guest' section not found.
> ERROR: Error constructing guest OS
>
> 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!

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?

Cheers,
Mrak

> I'll try upgrading to a more current version of xen, but did not
> like the 3.1.0 build procedures the last time I tried them ...
>
>
> -Tom
>
>
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-- 
Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!

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