From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTP id 13A54679E0 for ; Sat, 11 Mar 2006 10:12:43 +1100 (EST) Subject: Re: Unmapping pages from the linear addressing without HIGHMEM support From: Benjamin Herrenschmidt To: Dan Malek In-Reply-To: <051c9d8f422b0e5289b7083367cf44ca@embeddedalley.com> References: <1141942301.3603.12.camel@localhost.localdomain> <22544.1141981797@www088.gmx.net> <051c9d8f422b0e5289b7083367cf44ca@embeddedalley.com> Content-Type: text/plain Date: Sat, 11 Mar 2006 10:12:31 +1100 Message-Id: <1142032351.4057.29.camel@localhost.localdomain> Mime-Version: 1.0 Cc: debian-powerpc@lists.debian.org, linuxppc-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Fri, 2006-03-10 at 07:59 -0500, Dan Malek wrote: > On Mar 10, 2006, at 4:09 AM, Gerhard Pircher wrote: > > > That would mean I cannot reuse the code in dma-mapping.c, right? > > Sure you can. All you need to do is turn of BAT mapping, which > is as easy as using the 'nobats' command line parameter and > all of this code should just work for you. And the kernel will blow up in flames under various funny circumstances and you'll lose a fair amount of performances. The 6xx kernel requires at least the IBAT mapping the kernel text. Some of the exception handling code path can't deal with getting a hash fault at critical locations (they can mostly deal with data hash misses nowadays, but the code has to be accessible at all times). > > ... but I guess I have to setup my own page table for the reserved > > DMA memory area and implement my own alloc_pages() function!? > > No, that's already done for you behind all of these functions. > > Thanks. > > -- Dan > >