Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sat, 7 Jul 2001 08:21:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sat, 7 Jul 2001 08:21:46 -0400 Received: from router-100M.swansea.linux.org.uk ([194.168.151.17]:5386 "EHLO the-village.bc.nu") by vger.kernel.org with ESMTP id ; Sat, 7 Jul 2001 08:21:36 -0400 Subject: Re: (reposting) how to get DMA'able memory within 4GB on 64-bit m To: jgarzik@mandrakesoft.com (Jeff Garzik) Date: Sat, 7 Jul 2001 13:21:25 +0100 (BST) Cc: alan@lxorguk.ukuu.org.uk (Alan Cox), davem@redhat.com (David S. Miller), bcrl@redhat.com (Ben LaHaise), jes@sunsite.dk (Jes Sorensen), hiren_mehta@agilent.com ("MEHTA,HIREN (A-SanJose,ex1)"), linux-kernel@vger.kernel.org ('linux-kernel@vger.kernel.org') In-Reply-To: <3B46FDF1.A38E5BB6@mandrakesoft.com> from "Jeff Garzik" at Jul 07, 2001 08:17:53 AM X-Mailer: ELM [version 2.5 PL3] MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-Id: From: Alan Cox Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org > > So add another seven or eight years to your estimate > > Given a little more context, I thought we were talking specifically > about 64bit-PCI-on-32bit-machines? > > Assuming that, AFAICS Ben's statement seems more correct. > > And IMHO we definitely should not optimize for 64-bit-on-32-bit case. > Let CONFIG_HIGHMEM grow dma_addr_t to 64-bits, for that case only... I see no good way to optimise for 64bit dma on a 32bit box. The existing API is extremely clean, easy to understand and I don't agree with Dave's desire to write another whole concoction. We do need pci_set_dma_mask_bits(), which in itself lets drivers indicate SAC/DAC capable. We do want a way for nosey or fine tuned drivers to query SAC/DAC properties, but most drivers should be letting arch code make arch policy. Alan - 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/