From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.gmx.net (mail.gmx.net [213.165.64.20]) by ozlabs.org (Postfix) with SMTP id 668ADDE0BB for ; Sat, 19 Apr 2008 21:07:42 +1000 (EST) Content-Type: text/plain; charset="us-ascii" Date: Sat, 19 Apr 2008 13:07:40 +0200 From: "Gerhard Pircher" In-Reply-To: Message-ID: <20080419110740.107700@gmx.net> MIME-Version: 1.0 References: Subject: Re: [PATCH] [POWERPC] Port fixmap from x86 and use for kmap_atomic To: Kumar Gala Cc: linuxppc-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , -------- Original-Nachricht -------- > Datum: Thu, 17 Apr 2008 21:57:05 -0500 (CDT) > Von: Kumar Gala > An: Paul Mackerras > CC: linuxppc-dev@ozlabs.org > Betreff: [PATCH] [POWERPC] Port fixmap from x86 and use for kmap_atomic > The fixmap code from x86 allows us to have compile time virtual addresses > that we change the physical addresses of at run time. ... > +/* > + * Here we define all the compile-time 'special' virtual > + * addresses. The point is to have a constant address at > + * compile time, but to set the physical address only > + * in the boot process. We allocate these special addresses > + * from the end of virtual memory (0xfffff000) backwards. > + * Also this lets us do fail-safe vmalloc(), we > + * can guarantee that these special addresses and > + * vmalloc()-ed addresses never overlap. I don't understand how highmem works, but I'm just interested to know, if this implementation could conflict somehow with the non coherent DMA implementation in dma-noncoherent.c (which uses address space from 0xff100000 to 0xff300000 for DMA memory). On the other side could dma-noncoherent.c benefit from fixmaps so that it isn't necessary to configure a start address for DMA allocations? Thanks! best regards, Gerhard -- Psst! Geheimtipp: Online Games kostenlos spielen bei den GMX Free Games! http://games.entertainment.gmx.net/de/entertainment/games/free