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Re: [Xen-devel] determining if kernel is dom0 kernel or not.

To: xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-devel] determining if kernel is dom0 kernel or not.
From: Mark Williamson <mark.williamson@xxxxxxxxxxxx>
Date: Thu, 12 Jul 2007 14:35:43 +0100
Cc: Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx>, Keir Fraser <keir@xxxxxxxxxxxxx>, jd <jdsw2002@xxxxxxxxx>
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> Optional :
> Any history behind it containing 'control_d' ?
> Control Dom ?

Yeah, I should think that's what it stands for ;-)

Dom0's kernel knows if it's dom0, anyhow - it has to know it's supposed to 
manage various privileged stuff.  The /proc/xen/capabilities interface is 
just a convenient way of it telling userspace (was introduced, IIRC, for 
purposes such as making init scripts do the Right Thing withoout breaking in 
all cases, rather than having to be manually set up differently for native / 
dom0 / domU).

Cheers.
Mark

> Thanks
> /Jd
>
> --- Keir Fraser <keir@xxxxxxxxxxxxx> wrote:
> > On 11/7/07 21:38, "Ian Campbell"
> >
> > <Ian.Campbell@xxxxxxxxxxxxx> wrote:
> > > On Wed, 2007-07-11 at 20:18 +0100, Keir Fraser
> >
> > wrote:
> > >> If you want to detect dom0 specifically then
> >
> > that's trickier --
> >
> > >> /proc/xen/privcmd for example exists even in a
> >
> > domU, if the kernel is
> >
> > >> dom0-capable. You'd have to be root and then try
> >
> > a privileged hypercall. :-)
> >
> > > Doesn't /proc/xen/capabilities contain something
> >
> > different on dom0 vs.
> >
> > > domU?
> >
> > Oh yes, of course. It contains 'control_d' if you
> > are dom0.
> >
> >  -- Keir
> >
> >
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>
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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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