Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263455AbUCTQCv (ORCPT ); Sat, 20 Mar 2004 11:02:51 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263456AbUCTQCv (ORCPT ); Sat, 20 Mar 2004 11:02:51 -0500 Received: from 194.149.109.108.adsl.nextra.cz ([194.149.109.108]:27028 "EHLO gate2.perex.cz") by vger.kernel.org with ESMTP id S263455AbUCTQCt (ORCPT ); Sat, 20 Mar 2004 11:02:49 -0500 Date: Sat, 20 Mar 2004 16:58:21 +0100 (CET) From: Jaroslav Kysela X-X-Sender: perex@pnote.perex-int.cz To: Russell King Cc: Andrea Arcangeli , William Lee Irwin III , linux-kernel@vger.kernel.org, Andrew Morton , Linus Torvalds Subject: Re: can device drivers return non-ram via vm_ops->nopage? In-Reply-To: <20040320154419.A6726@flint.arm.linux.org.uk> Message-ID: References: <20040320133025.GH9009@dualathlon.random> <20040320144022.GC2045@holomorphy.com> <20040320150621.GO9009@dualathlon.random> <20040320154419.A6726@flint.arm.linux.org.uk> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1073 Lines: 30 On Sat, 20 Mar 2004, Russell King wrote: > Actually, ALSA is broken in that respect - it isn't portable as it > stands. It isn't the API which is broken - it's ALSA which is broken. > Performing virt_to_page() on any non-direct mapped RAM page (which > means the value returned from dma_alloc_coherent or pci_alloc_consistent) > is undefined. > > One of my current projects is fixing this crap in ALSA. Yes, but if there's no API in the kernel code allowing to obtain page pointers using any value returned from dma_alloc_coherent(), then we cannot fix this problem. So, it's not much subsystem (ALSA) problem, but kernel core is not matured enough. The same problem is for the cache coherency for mmaped pages. Jaroslav ----- Jaroslav Kysela Linux Kernel Sound Maintainer ALSA Project, SuSE Labs - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/