linux-kernel - Re: [PATCH v12 10/18] xen/pvh: Update E820 to work with PVH (v2)

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Message-ID: <20140104022526.GA14630@pegasus.dumpdata.com>
Date:	Fri, 3 Jan 2014 21:25:30 -0500
From:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:	Mukesh Rathor <mukesh.rathor@...cle.com>
Cc:	David Vrabel <david.vrabel@...rix.com>,
	linux-kernel@...r.kernel.org, xen-devel@...ts.xenproject.org,
	boris.ostrovsky@...cle.com, stefano.stabellini@...citrix.com
Subject: Re: [PATCH v12 10/18] xen/pvh: Update E820 to work with PVH (v2)

On Fri, Jan 03, 2014 at 05:23:37PM -0800, Mukesh Rathor wrote:
> On Thu, 2 Jan 2014 13:41:34 -0500
> Konrad Rzeszutek Wilk <konrad.wilk@...cle.com> wrote:
> 
> > On Thu, Jan 02, 2014 at 04:14:32PM +0000, David Vrabel wrote:
> > > On 01/01/14 04:35, Konrad Rzeszutek Wilk wrote:
> > > > From: Mukesh Rathor <mukesh.rathor@...cle.com>
> > > > 
> > > > In xen_add_extra_mem() we can skip updating P2M as it's managed
> > > > by Xen. PVH maps the entire IO space, but only RAM pages need
> > > > to be repopulated.
> > > 
> > > So this looks minimal but I can't work out what PVH actually needs
> > > to do here.  This code really doesn't need to be made any more
> > > confusing.
> > 
> > I gather you prefer Mukesh's original version?
> 
> I think Konrad thats easier to follow as one can quickly spot
> the PVH difference... but your call.

I prefer the one that re-uses the existing logic. That has been - both
in the hypervisor and in the Linux kernel for PVH - the path - just do
nice little one-offs that do something simpler and easier than the
old PV path.

That way one can easily spot how PV vs PVH works for certain operations.

It also from a testing coverage perspective means we end up using the
same codepath for both PV and PVH - so we do get more testing exposure
for different modes.

> 
> thanks
> mukesh
> 
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