Bug#500336: patch for grub detection

[Ian Campbell]

On Thu, 2008-10-30 at 16:45 +0100, Raphael Hertzog wrote:
> On Thu, 30 Oct 2008, Ian Campbell wrote:
> > This means that if I am running a pv ops kernel and I install a
> > non-pvops kernel for whatever reason then my menu.lst will omit it.
> 
> Sure. 
> 
> Let's come back to the root of this bug report, the problem is that
> 2.6.26-1-686-bigmem has CONFIG_XEN and CONFIG_PARAVIRT and is considered
> to be a suitable dom0 kernel when in fact it's not.
> 
> They are added to xen0Kernels by the second loop:
> # Second new style CONFIG_PARAVIRT kernels with xen support. There is
> # no distinction between xen0 and xenU in these kernels.
> for ver in `grep -l CONFIG_PARAVIRT=y /boot/config* | sed -e s%/boot/config-%%`; do
>   if ! grep -q CONFIG_XEN=y /boot/config-$ver ; then
>       continue
>   fi
> [...]
> 
> What's the reasoning behind this loop ? All the suitable kernels are already selected
> by the first loot that matches CONFIG_XEN + CONFIG_XEN_PRIVILEGED_GUEST.
> 
> Can't we simply drop this loop and be done with it ? What do I miss ?

Current paravirt ops kernels cannot be booted as a dom0 but future ones
will be. Currently there is no way to tell them apart, there may or may
not be a variable similar to CONFIG_XEN_PRIVILEGED_GUEST for those
kernels when dom0 support goes upstream. However we have no way of
knowing what will happen here.

(I may have been mistakenly thought we were discussing that a "native
style" entry was being created for the -xen-686 kernel (in addition to
one which specified a hypervisor).)

> All the kernels are still listed individually but that category of kernel is no
> more combined with the hypervisor if it's available.
> 
> We at least reduce the number of bad combinations without dropping any good
> combination if I trust the table given in
> http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=500336#25

But this table *does* drop a good combination, which is a CONFIG_XEN +
no CONFIG_PARAVIRT when used inside a domU.

Ian.

-- 
Ian Campbell
Current Noise: Sabbat - The Clerical Conspiracy (Live)

You're almost as happy as you think you are.