From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Peer Chen" Subject: Re: Re: [PATCH] sata_nv,ahci: add the ahci legacy mode support to sata_nv Date: Tue, 25 Sep 2007 17:08:23 +0800 Message-ID: <200709251708208579514@gmail.com> References: <200709251323031982245@gmail.com>, <46F8B3F8.1050909@garzik.org>, <200709251552483357334@gmail.com>, <46F8C33A.3060601@garzik.org> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from wa-out-1112.google.com ([209.85.146.183]:35883 "EHLO wa-out-1112.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750864AbXIYJI3 (ORCPT ); Tue, 25 Sep 2007 05:08:29 -0400 Received: by wa-out-1112.google.com with SMTP id v27so2335230wah for ; Tue, 25 Sep 2007 02:08:28 -0700 (PDT) Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: jeff Cc: linux-kernel , linux-ide , akpm Yes,I hear what you are saying but user should know what they are setti= ng in BIOS,there are lots of ways to change the BIOS setting result in = unbootable system not only change AHCI/IDE mode. If they encounter boot= ing failure after changing the BIOS setting,they should restore it. Using legacy driver for legacy mode won't affect user to enjoy the feat= ure of AHCI,just select AHCI/RAID mode will ok. As I know, Intel did it in the same way,and I think it's reasonable. ------------------ =20 Peer Chen 2007-09-25 ------------------------------------------------------------- =B7=A2=BC=FE=C8=CB=A3=BAJeff Garzik =B7=A2=CB=CD=C8=D5=C6=DA=A3=BA2007-09-25 16:13:52 =CA=D5=BC=FE=C8=CB=A3=BAPeer Chen =B3=AD=CB=CD=A3=BAlinux-kernel; linux-ide; akpm =D6=F7=CC=E2=A3=BARe: [PATCH] sata_nv,ahci: add the ahci legacy mode su= pport to sata_nv Peer Chen wrote: > We have three mode for one controller - IDE/RAID/AHCI, we want sata_n= v being load when user select the IDE mode in BIOS, load ahci driver if= RAID/AHCI being selected, which will verify if our legacy mode work we= ll and have additional option if there is any > bug for the ahci mode. I understand that logic, but look at what happens in practice: 1) User installs new OS in AHCI mode. Distro updates initramfs (loaded= =20 at kernel boot time, with boot drivers) to include ahci driver. 2) User reboots into BIOS setup, and switches from AHCI mode to IDE mod= e. 3) BIOS setup reboots computer. 4) OS kernel and initramfs image are loaded. ahci driver load fails. 5) User is left without a bootable system. The same situation happens in reverse, if you install in IDE mode=20 (sata_nv in initramfs), and then switch to AHCI/RAID mode. Additionally, AHCI provides better performance and more direct exposure= =20 to the SATA frames. This is key for supporting many modern SATA=20 features that cannot be accessed via IDE legacy mode. AHCI lacks=20 in-silicon simulation of an IDE interface, which time has shown is a=20 less stable, edge-case-prone approach to SATA. I do not find the "verify nvidia's legacy mode works" argument=20 compelling; that is not the kernel's job, nor the user's. And if there= =20 is an AHCI silicon bug, let us deal with that when such a bug appears. Overall, AFAICS this patch -introduces- new ways for the user to easily= =20 render their systems unbootable. Jeff