From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCH RFC] ahci: implement handoff quirk Date: Tue, 14 Apr 2009 18:16:16 +0900 Message-ID: <49E45460.8010809@kernel.org> References: <485882FE.1060409@kernel.org> <49E0CB5B.3070807@garzik.org> <49E0D8B7.8010206@kernel.org> <49E0DB1E.8070701@garzik.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from hera.kernel.org ([140.211.167.34]:55048 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751166AbZDNJRW (ORCPT ); Tue, 14 Apr 2009 05:17:22 -0400 In-Reply-To: <49E0DB1E.8070701@garzik.org> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Jeff Garzik Cc: IDE/ATA development list , "Zhao, Richard" , shane.huang@amd.com Jeff Garzik wrote: > Tejun Heo wrote: >> Jeff Garzik wrote: >>> We probably need to do this... >>> >>> it's not a controller requirement but a BIOS one, so in theory even an >>> existing, deployed AHCI 1.2 platform could suddenly require BIOS/OS >>> handoff, if a BIOS update suddenly starts doing new and weird stuff >>> in SMI. >>> >>> Note that we need to do BIOS/OS handoff upon resume as well as at boot >>> time. >> >> Yeah, probably. Do you know of any system which makes use of this >> feature? I'm a bit uneasy about committing it without any testing. > > I don't. > > But the purpose of the feature is to tell BIOS to cleanup and stop using > the hardware. It's a dumb feature, because of compatibility realities, > but hey, other network and SCSI drivers have been doing this sort of > synchronization with their on-board firmwares for years. > > IMO the more dangerous route is to continue loading ahci, without first > telling the BIOS to clean up and get out of our way. Hmmm.... yeah, I'm just worried a bit about adding a chunk of completely untested code. How about adding a big fat warning message which gets triggered if the handoff thing seems to be active? Thanks. -- tejun