Re: xen: how does XEN_PRIVILEGED_GUEST work?

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Sat, Mar 23, 2013 at 02:59:35PM +0100, Paul Bolle wrote:
> On Sat, 2013-03-23 at 09:22 -0400, Konrad Rzeszutek Wilk wrote:
> > On Fri, Mar 22, 2013 at 11:37:35PM +0100, Paul Bolle wrote:
> > > 1) Its Kconfig entry is preceded with this comment:
> > >     # Dummy symbol since people have come to rely on the PRIVILEGED_GUEST
> > >     # name in tools.
> > > 
> > > What does that mean?
> > 
> > [root@phenom minutes]# cat /etc/grub.d/20_linux_xen |grep PRIV
> >         if (grep -qx "CONFIG_XEN_DOM0=y" "${config}" 2> /dev/null || grep -qx "CONFIG_XEN_PRIVILEGED_GUEST=y" "${config}" 2> /dev/null); then echo -n "$i " ; fi
> 
> Thanks.
> 
> Can userspace require the build system to keep using some Kconfig symbol
> by doing tests like these? Anyhow, if that's the only tool then

I don't know if there are rules written down for this sort of thing - but
I presume there are some utilities that check the /proc/config.gz to
see if certain options are enabled? This is not that much different from that.

> XEN_PRIVILEGED_GUEST can be dropped. XEN_PRIVILIGED_GUEST should always
> be equal to XEN_DOM0 so this if () test will evaluate identically with
> the sub-test for CONFIG_XEN_PRIVILIGED_GUEST removed.

That is the only tool that I am aware of.

But if we wanted to drop one of those CONFIG_ options I would be more happy
with dropping of the XEN_DOM0. As the initial domain is not that different
from any PV domain - except that it can do ACPI, VGA, and some EFI stuff.
In essence it is a priviliged guest type.

It might make more sense to have the XEN_PRIVILIGED_GUEST be the option
that that would define whether there should be a dependency on the ACPI, VGA, etc
stuff.

Unfortunatly the XEN_DOM0 seems to be so interleaved in the header/source code
that this would take some surgery to get right.

> 
> 
> Paul Bolle
>