From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: Arch specific mmap attributes Date: Wed, 07 Apr 2010 00:18:48 -0700 (PDT) Message-ID: <20100407.001848.257489037.davem@davemloft.net> References: <20100407095145.FB70.A69D9226@jp.fujitsu.com> <20100407.000343.181989028.davem@davemloft.net> <20100407161203.FB81.A69D9226@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:33439 "EHLO sunset.davemloft.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932452Ab0DGHSq (ORCPT ); Wed, 7 Apr 2010 03:18:46 -0400 In-Reply-To: <20100407161203.FB81.A69D9226@jp.fujitsu.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: kosaki.motohiro@jp.fujitsu.com Cc: benh@kernel.crashing.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org From: KOSAKI Motohiro Date: Wed, 7 Apr 2010 16:14:29 +0900 (JST) >> From: KOSAKI Motohiro >> Date: Wed, 7 Apr 2010 15:03:45 +0900 (JST) >> >> > I'm not against changing kernel internal. I only disagree mmu >> > attribute fashion will be become used widely. >> >> Desktop already uses similar features via PCI mmap >> attributes and such, not to mention MSR settings on >> x86. > > Probably I haven't catch your mention. Why userland process > need to change PCI mmap attribute by mmap(2)? It seems kernel issue. It uses PCI specific fd ioctls to change the attributes. It's the same thing as extending the mmap() attribute space, but in a device specific way. I think evice and platform specific mmap() attributes are basically inevitable, at any level, embedded or desktop or whatever. The fact that we've hacked around the issue with device specific interfaces like the PCI device ioctls, is no excuse to not tackle the issue directly and come up with something usable.