From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Paul E. McKenney" Subject: Re: [PATCH] x86: PAT: Documentation: update overlapping ioremap hack recommendation Date: Fri, 4 Mar 2016 13:09:00 -0800 Message-ID: <20160304210900.GT3577@linux.vnet.ibm.com> References: <1457040108-27358-1-git-send-email-mcgrof@kernel.org> <20160303214233.GN3577@linux.vnet.ibm.com> <20160304192326.GU25240@wotan.suse.de> Reply-To: paulmck@linux.vnet.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from e18.ny.us.ibm.com ([129.33.205.208]:42087 "EHLO e18.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759668AbcCDVJi (ORCPT ); Fri, 4 Mar 2016 16:09:38 -0500 Received: from localhost by e18.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 4 Mar 2016 16:09:38 -0500 Content-Disposition: inline In-Reply-To: <20160304192326.GU25240@wotan.suse.de> Sender: linux-arch-owner@vger.kernel.org List-ID: To: "Luis R. Rodriguez" Cc: bp@alien8.de, mingo@kernel.org, tglx@linutronix.de, hpa@zytor.com, toshi.kani@hp.com, airlied@redhat.com, benh@kernel.crashing.org, mst@redhat.com, vinod.koul@intel.com, jgross@suse.com, daniel.vetter@ffwll.ch, luto@amacapital.net, linux-fbdev@vger.kernel.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, x86@kernel.org, linux-doc@vger.kernel.org, corbet@lwn.net On Fri, Mar 04, 2016 at 08:23:26PM +0100, Luis R. Rodriguez wrote: > On Thu, Mar 03, 2016 at 01:42:33PM -0800, Paul E. McKenney wrote: > > On Thu, Mar 03, 2016 at 01:21:48PM -0800, Luis R. Rodriguez wrote: > > > The current documentation refers to using set_memor_wc() as a > > > possible hole strategy when you have overlapping ioremap() regions, > > > that's incorrect as set_memory_*() helpers can only be used on RAM, > > > not IO memory. This fixes that, and updates the documention to > > > *strongly* discourage overlapping ioremap() memory uses, but also > > > documents a possible solution should there really be no other > > > option. > > > > > > Signed-off-by: Luis R. Rodriguez > > > > Given an Acked-by or better from the guys on the TO line, I would be > > happy to queue it. > > I'll need to respin as fortunately I ended up actually not needing > to do an overlap on atyfb, and instead just let MTRR be effective > over an entire range that included both write-combining and strong > UC attributes. It was a bit fuzzy as this while ago, and since its > also obscure, its more reason to document now. > > Will spin a v2. Sounds good! Thanx, Paul