Bug#414471: [Pkg-xen-devel] Bug#414471: xen-hypervisor-3.0.3-1-i386-pae: small bug in package description

[Ralph Passgang]

Am Montag, 12. März 2007 02:06 schrieb Roberto C. Sanchez:
> On Mon, Mar 12, 2007 at 01:51:43AM +0100, Sander Marechal wrote:
> > Package: xen-hypervisor-3.0.3-1-i386-pae
> > Version: 3.0.3-0-2
> > Severity: minor
> >
> >
> > The package description reads:
> >
> >   This version of the hypervisor is built with PAE enabled, in order to
> >   support systems with more than 4GB of memory.  If you have less than
> >   that you should probably choose the non -pae version.
> >
> > That's not entirely true. I tried installing the non-pae version on my
> > ProLiant server. The server supports up to 24 Gb RAM but only 1 Gb is
> > actually installed. The non-pae version does not run and complains that
> > the OS cannot be setup as dom0.
> >
> > I think the package description should be amended so it clearly states
> > that the -pae version is needed if the system *supports* more than 4Gb
> > RAM.
>
> Strange.  My system supports only 3 GB RAM, but the CPU has PAE enabled:

There might be a difference what your board supports (for example the amount 
of ram sockets) and what your bios/chipset and cpu supports.

It's possible that you can only install 3gb of ram, but your system will most 
likely support pae anyways.

> $ cpuid |grep -i pae
> PAE - Page Address Extensions
>
> Could it be that the behavior is more a function of the chipset than of
> the CPU itself?

All you hardware must support it. Try to take a look in your bios settings. A 
lot of servers have a kind of bios where you can enable or disable pae alias 
48bit addressing. On intel boars this can often be found in a submenu 
called "memory management".

But PAE doesn't bring you anything if you have less than at least 3,5gb 
installed. 

On the other hand, the most recent debian kernel are pae kernels and so you 
have to use the pae hypervisor to use xen. If you want to use a non-pae 
hypervisor & kernel, you have to compile it yourself (or switch back to 
2.6.18-3).

> Regards,
>
> -Roberto