Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261651AbUCVD3S (ORCPT ); Sun, 21 Mar 2004 22:29:18 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261652AbUCVD3S (ORCPT ); Sun, 21 Mar 2004 22:29:18 -0500 Received: from fw.osdl.org ([65.172.181.6]:63631 "EHLO mail.osdl.org") by vger.kernel.org with ESMTP id S261651AbUCVD3P (ORCPT ); Sun, 21 Mar 2004 22:29:15 -0500 Date: Sun, 21 Mar 2004 19:28:59 -0800 (PST) From: Linus Torvalds To: David Woodhouse cc: Jeff Garzik , Russell King , Christoph Hellwig , William Lee Irwin III , Andrew Morton , Andrea Arcangeli , linux-kernel@vger.kernel.org Subject: Re: can device drivers return non-ram via vm_ops->nopage? In-Reply-To: <1079913775.17681.499.camel@imladris.demon.co.uk> Message-ID: References: <20040320121345.2a80e6a0.akpm@osdl.org> <20040320205053.GJ2045@holomorphy.com> <20040320222639.K6726@flint.arm.linux.org.uk> <20040320224500.GP2045@holomorphy.com> <1079901914.17681.317.camel@imladris.demon.co.uk> <20040321204931.A11519@infradead.org> <1079902670.17681.324.camel@imladris.demon.co.uk> <20040321222327.D26708@flint.arm.linux.org.uk> <405E1859.5030906@pobox.com> <20040321225117.F26708@flint.arm.linux.org.uk> <405E23A5.7080903@pobox.com> <1079913775.17681.499.camel@imladris.demon.co.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: 1014 Lines: 24 On Mon, 22 Mar 2004, David Woodhouse wrote: > > You are assuming that dma_alloc_coherent() will always return memory of > that second kind -- host-side RAM, not PCI-side. That hasn't previously > been a requirement, and there are machines out there on which it makes a > lot more sense for dma_alloc_coherent() to use some SRAM which happens > to be hanging off the I/O bus than it does to use host RAM. So? Those architectures can just allocate "struct page" entries for that memory too. There is a point where we should not care about idiotic architectures any more. We should care about what happens in 99% of all architectures, and the rest get to work around their _own_ quirks. We do not make the VM uglier for some insane "it can happen" case. Linus - 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/