From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matt Sealey Subject: Re: Read Prefetch, Post Write on IDE chipsets Date: Sun, 02 Sep 2007 15:04:22 +0100 Message-ID: <46DAC2E6.6070102@genesi-usa.com> References: <46DAB1DF.5050109@genesi-usa.com> <20070902150034.7a6713f5@the-village.bc.nu> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mithrandir.softwarenexus.net ([66.98.186.96]:3697 "EHLO mail.genesi-usa.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756344AbXIBOCu (ORCPT ); Sun, 2 Sep 2007 10:02:50 -0400 In-Reply-To: <20070902150034.7a6713f5@the-village.bc.nu> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Alan Cox Cc: linux-ide@vger.kernel.org Alan Cox wrote: > On Sun, 02 Sep 2007 13:51:43 +0100 > Matt Sealey wrote: > >> But, what is it? I've never seen any documentation but which register to use >> to toggle it.. no vendor recommendations to turn it on, it seems like a rather >> secret feature..? > > Chipset specific. Some public documentation discusses it for certain > chips (eg the Intel ATA tuning guidelines). For others you may need the > BIOS vendor manual or similar. All I see is.. that if you want to turn it on, you must make sure of a few things. There is no discussion on what it DOES, I assume it simply buffers a little more somewhere (somehow?) inside the chipset, for the purpose of allowing more streamlined PIO access. But it has some awesome limitations.. Is it even relevant anymore? Does anyone even notice if these features are turned off? -- Matt Sealey Genesi, Manager, Developer Relations