From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steven Scholz Subject: Impact of no_lba48{_dma} = 1 ? Date: Wed, 07 Feb 2007 10:56:14 +0100 Message-ID: <45C9A23E.3030201@imc-berlin.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from mail.imc-berlin.de ([217.110.46.186]:47900 "EHLO mx1.imc-berlin.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030616AbXBGJ4R (ORCPT ); Wed, 7 Feb 2007 04:56:17 -0500 Received: from localhost (localhost [127.0.0.1]) by mx1.imc-berlin.de (Postfix) with ESMTP id 01CD71457B for ; Wed, 7 Feb 2007 10:56:16 +0100 (CET) Received: from mx1.imc-berlin.de ([127.0.0.1]) by localhost (mx1.imc-berlin.de [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 9Xznx5h7fkbv for ; Wed, 7 Feb 2007 10:56:15 +0100 (CET) Received: from mailserver.berlin.imc-berlin.de (mailserver.berlin.imc-berlin.de [10.0.0.19]) by mx1.imc-berlin.de (Postfix) with ESMTP id E11DD1457A for ; Wed, 7 Feb 2007 10:56:15 +0100 (CET) Received: from localhost (localhost [127.0.0.1]) by mailserver.berlin.imc-berlin.de (Postfix) with ESMTP id D476410B07 for ; Wed, 7 Feb 2007 10:56:15 +0100 (CET) Received: from [10.0.2.10] (scholz.berlin.imc-berlin.de [10.0.2.10]) by mailserver.berlin.imc-berlin.de (Postfix) with ESMTP id E7A87A071 for ; Wed, 7 Feb 2007 10:56:14 +0100 (CET) Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: linux-ide@vger.kernel.org Hi all, on our embedded system we connected a HDD via FPGA driectly to the CPU. And wrote a evry simple IDE driver for it. BAsicly the HDD internbal registers are just memory mapped. No DMA is supported by the hardware. But I think it would be capable of 48bit LBA mode (which just means setting the HOB bit in the device control register of the HDD correctly?) Now I wonder what the impact of setting hwif->no_lba48 = 1; /* 1 = cannot do LBA48 */ hwif->no_lba48_dma = 1; /* 1 = cannot do LBA48 DMA */ would be. IIUC then no_lba48 would limit the useable size to 130GB? Will every HDD work with no_lba48 set to 1? Even those which actually support 48bit LBA? How about performance impact of if (hwif->no_lba48 || hwif->no_lba48_dma) hwif->rqsize = 256; else hwif->rqsize = 65536; in ide-probe.c ? Thanks a million for any pointers! Steven