From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: AHCI problem with hotplug Date: Fri, 02 Jan 2009 12:12:06 +0900 Message-ID: <495D8606.5070807@kernel.org> References: <494178E3.6030305@cybernetics.com> <49588784.4020808@kernel.org> <4958E3DC.7080009@cybernetics.com> <49591710.7040102@shaw.ca> <49596D9E.3040904@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from hera.kernel.org ([140.211.167.34]:35875 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751702AbZABDMV (ORCPT ); Thu, 1 Jan 2009 22:12:21 -0500 In-Reply-To: <49596D9E.3040904@kernel.org> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Robert Hancock Cc: Tony Battersby , Jeff Garzik , IDE/ATA development list Hello, Tejun Heo wrote: > This is consistent with the BIOS tristating those ports. I don't > remember the name of the register. I'll look it up later. Yeah, the PCS register. From ICH8 datasheet (ICH7 datasheet doesn't have the following paragraph but it's what the BIOS is supposed to do all the same). If an AHCI-aware or RAID enabled operating system is being booted then system BIOS shall insure that all supported SATA ports are enabled prior to passing control to the OS. Once the AHCI aware OS is booted it becomes the enabling/disabling policy owner for the individual SATA ports. This is accomplished by manipulating a port=E2= =80=99s PxSCTL and PxCMD fields. Because an AHCI or RAID aware OS will typically not have knowledge of the PxE bits and because the PxE bits act as master on/off switches for the ports, pre- boot software must insure that these bits are set to =E2=80=981=E2=80=99 prior to b= ooting the OS, regardless as to whether or not a device is currently on the port. Can you please post the output of "lpsci -nnvvvxxx"? --=20 tejun