Re: [PATCH] tools/hvmloader: move shared_info to reserved memory area

[Olaf Hering <olaf@aepfle.de>]

On Fri, Oct 26, Konrad Rzeszutek Wilk wrote:

> On Thu, Oct 25, 2012 at 01:46:45PM +0200, Olaf Hering wrote:
> > On Thu, Oct 25, Keir Fraser wrote:
> > 
> > > To be honest, given that the XenPVHVM extensions to Linux won't have been
> > > tested on such old hypervisors, it wouldn't be a bad thing to bail on
> > > setting up the extensions when you detect running on a really old Xen
> > > version (e.g., earlier than 3.4.0) anyway. There's a fair chance of doing
> > > more harm than good?
> > 
> > I could stick such a check into
> > arch/x86/xen/enlighten.c:x86_hyper_xen_hvm->detect, by rearranging the
> > code of xen_hvm_platform and init_hvm_pv_info.  Konrad, what do you
> > think about that? Recent changes indicate that you did some testing on
> > 3.4 based hosts.
> 
> Sure. It might make sense to streamline this a bit. Meaning after the
> version check, have an int (or function) called 'xen_old_hypervisor()'
> which your code and the XenBus code could call?

Oh, my take would be to return false in xen_hvm_platform if the
hypervisor is 3.3 or older, so that the guest does not use the PVonHVM
extensions.

Olaf