linux-kernel - Re: [PATCH] x86/mm/init: respect memblock reserved regions when destroying mappings

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Date:	Mon, 7 Feb 2011 18:58:14 +0000
From:	Stefano Stabellini <stefano.stabellini@...citrix.com>
To:	Yinghai Lu <yinghai@...nel.org>
CC:	Stefano Stabellini <Stefano.Stabellini@...citrix.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Jeremy Fitzhardinge <jeremy@...p.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"x86@...nel.org" <x86@...nel.org>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Jan Beulich <JBeulich@...ell.com>
Subject: Re: [PATCH] x86/mm/init: respect memblock reserved regions when
 destroying mappings

On Mon, 7 Feb 2011, Yinghai Lu wrote:
> On 02/07/2011 08:50 AM, Stefano Stabellini wrote:
> > On Sun, 6 Feb 2011, Yinghai Lu wrote:
> >> On 02/05/2011 11:30 PM, H. Peter Anvin wrote:
> >>> On 02/05/2011 11:02 PM, Yinghai Lu wrote:
> >>>> why not just move calling cleanup_highmap down?
> >>>>
> >>>> something like attached patch.
> >>>
> >>> This patch looks very clean and looks on the surface of it like it is
> >>> removing some ugly ad hoc code, but (as always) it needs a description
> >>> about the problem it solves and why it is correct.
> >>
> >> Sure.
> >>
> >>
> >> Jeremy and xen guys, can you please check if it works well with xen ?
> >>
> > 
> > Actually this patch makes things worse on xen, because before
> > cleanup_highmap() wasn't called at all on xen (on purpose) and now it
> > is, fully destroying all the mappings we have at _end.
> > 
> > Can we add a check on memblock reserved regions in cleanup_highmap()?
> > Otherwise could we avoid calling cleanup_highmap() at all on xen?
> 
> why DO xen need over-mapped kernel initial mapping?
> 
> what is in that range after _end to 512M?

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