From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 2 May 2002 16:21:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 2 May 2002 16:21:43 -0400 Received: from dsl-213-023-038-046.arcor-ip.net ([213.23.38.46]:56225 "EHLO starship") by vger.kernel.org with ESMTP id ; Thu, 2 May 2002 16:21:41 -0400 Content-Type: text/plain; charset=US-ASCII From: Daniel Phillips To: Roman Zippel Subject: Re: discontiguous memory platforms Date: Thu, 2 May 2002 22:14:02 +0200 X-Mailer: KMail [version 1.3.2] Cc: Andrea Arcangeli , Ralf Baechle , Russell King , linux-kernel@vger.kernel.org In-Reply-To: <3CD19640.3B85BF76@linux-m68k.org> MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Message-Id: Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thursday 02 May 2002 21:40, Roman Zippel wrote: > Daniel Phillips wrote: > > > Patching the kernel how, and where? > > Check for example in asm-ppc/page.h the __va/__pa functions. OK, by 'patching the kernel' you must mean 'initialize the m68k_memory array'. The loop you use does have one advantage: it can handle size variation vs a shift-lookup strategy. It's a lot more expensive though, and these are heavily used operations. > > > Anyway, I agree with Andrea, that another mapping isn't really needed. > > > Clever use of the mmu should give you almost the same result. > > > > We *are* making clever use of the mmu in config_nonlinear, it is doing the > > nonlinear kernel virtual mapping for us. Did you have something more clever > > in mind? > > I mean to map the memory where you need it. The physical<->virtual > mapping won't be one to one, but you won't need another abstraction and > the current vm is already basically able to handle it. I'll accept 'not needed for 68K', though I guess config_nonlinear will work perfectly well for you and be faster than the loops. However, some of the problems that config_nonlinear solves cannot be solved by any existing kernel mechanism. We've been over the NUMA-Q and mips32 cases in detail, so I won't reiterate. Thanks for your input. -- Daniel