From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753112Ab1HQKh0 (ORCPT ); Wed, 17 Aug 2011 06:37:26 -0400 Received: from mail.skyhub.de ([78.46.96.112]:55908 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752919Ab1HQKhX (ORCPT ); Wed, 17 Aug 2011 06:37:23 -0400 Date: Wed, 17 Aug 2011 12:37:17 +0200 From: Borislav Petkov To: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, rientjes@google.com, hpa@linux.intel.com Cc: linux-tip-commits@vger.kernel.org Subject: Re: [tip:x86/mm] x86, mm: Allow ZONE_DMA to be configurable Message-ID: <20110817103717.GA5172@liondog.tnic> Mail-Followup-To: Borislav Petkov , mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, rientjes@google.com, hpa@linux.intel.com, linux-tip-commits@vger.kernel.org References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, May 16, 2011 at 11:13:07PM +0000, tip-bot for David Rientjes wrote: > Commit-ID: dc382fd5bcca7098a984705ed6ac880f539d068e > Gitweb: http://git.kernel.org/tip/dc382fd5bcca7098a984705ed6ac880f539d068e > Author: David Rientjes > AuthorDate: Mon, 16 May 2011 13:54:10 -0700 > Committer: H. Peter Anvin > CommitDate: Mon, 16 May 2011 14:03:28 -0700 > > x86, mm: Allow ZONE_DMA to be configurable > > ZONE_DMA is unnecessary for a large number of machines that do not > require less than 32-bit DMA addressing, e.g. ISA legacy DMA or PCI > cards with a restricted DMA address mask. > > This patch allows users to disable ZONE_DMA for x86 if they know they > will not be using such devices with their kernel. > > This prevents the VM from unnecessarily reserving a ratio of memory > (defaulting to 1/256th of system capacity) with lowmem_reserve_ratio > for such allocations when it will never be used. > > Signed-off-by: David Rientjes > Link: http://lkml.kernel.org/r/alpine.DEB.2.00.1105161353560.4353@chino.kir.corp.google.com > Signed-off-by: H. Peter Anvin This causes the ZONE_DMA menu option to appear in the toplevel menu of the kernel configurator instead of under EXPERT, where it should belong IMO. > --- > arch/x86/Kconfig | 9 ++++++++- > arch/x86/mm/init_32.c | 2 ++ > arch/x86/mm/init_64.c | 2 ++ > 3 files changed, 12 insertions(+), 1 deletions(-) > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index 648fca4..0eb801a 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -112,7 +112,14 @@ config MMU > def_bool y > > config ZONE_DMA > - def_bool y > + bool "DMA memory allocation support" if EXPERT > + default y > + help > + DMA memory allocation support allows devices with less than 32-bit > + addressing to allocate within the first 16MB of address space. > + Disable if no such devices will be used. > + > + If unsure, say Y. maybe this should go into init/Kconfig ? Thanks. -- Regards/Gruss, Boris.