From mboxrd@z Thu Jan  1 00:00:00 1970
Date: Mon, 5 May 2008 00:08:25 +0200
From: Andrea Arcangeli <andrea@qumranet.com>
Subject: Re: [PATCH 01 of 11] mmu-notifier-core
Message-ID: <20080504220824.GA21051@duo.random>
References: <patchbomb.1209740703@duo.random> <1489529e7b53d3f2dab8.1209740704@duo.random> <20080504191345.GD18857@sgi.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20080504191345.GD18857@sgi.com>
Sender: owner-linux-mm@kvack.org
Return-Path: <owner-linux-mm@kvack.org>
To: Robin Holt <holt@sgi.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, Christoph Lameter <clameter@sgi.com>, Jack Steiner <steiner@sgi.com>, Nick Piggin <npiggin@suse.de>, Peter Zijlstra <a.p.zijlstra@chello.nl>, kvm-devel@lists.sourceforge.net, Kanoj Sarcar <kanojsarcar@yahoo.com>, Roland Dreier <rdreier@cisco.com>, Steve Wise <swise@opengridcomputing.com>, linux-kernel@vger.kernel.org, Avi Kivity <avi@qumranet.com>, linux-mm@kvack.org, general@lists.openfabrics.org, Hugh Dickins <hugh@veritas.com>, Rusty Russell <rusty@rustcorp.com.au>, Anthony Liguori <aliguori@us.ibm.com>, Chris Wright <chrisw@redhat.com>, Marcelo Tosatti <marcelo@kvack.org>, Eric Dumazet <dada1@cosmosbay.com>, "Paul E. McKenney" <paulmck@us.ibm.com>
List-ID: <linux-mm.kvack.org>

On Sun, May 04, 2008 at 02:13:45PM -0500, Robin Holt wrote:
> > diff --git a/mm/Kconfig b/mm/Kconfig
> > --- a/mm/Kconfig
> > +++ b/mm/Kconfig
> > @@ -205,3 +205,6 @@ config VIRT_TO_BUS
> >  config VIRT_TO_BUS
> >  	def_bool y
> >  	depends on !ARCH_NO_VIRT_TO_BUS
> > +
> > +config MMU_NOTIFIER
> > +	bool
> 
> Without some text following the bool keyword, I am not even asked for
> this config setting on my ia64 build.

Yes, this was explicitly asked by Andrew after his review. This is the
explanation pasted from the changelog.

3) It'd be a waste to add branches in the VM if nobody could possibly
   run KVM/GRU/XPMEM on the kernel, so mmu notifiers will only enabled
   if CONFIG_KVM=m/y. In the current kernel kvm won't yet take
   advantage of mmu notifiers, but this already allows to compile a
   KVM external module against a kernel with mmu notifiers enabled and
   from the next pull from kvm.git we'll start using them. And
   GRU/XPMEM will also be able to continue the development by enabling
   KVM=m in their config, until they submit all GRU/XPMEM GPLv2 code
   to the mainline kernel. Then they can also enable MMU_NOTIFIERS in
   the same way KVM does it (even if KVM=n). This guarantees nobody
   selects MMU_NOTIFIER=y if KVM and GRU and XPMEM are all =n.

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>