Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935353AbZLQBj3 (ORCPT ); Wed, 16 Dec 2009 20:39:29 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S936063AbZLQBiO (ORCPT ); Wed, 16 Dec 2009 20:38:14 -0500 Received: from e31.co.us.ibm.com ([32.97.110.149]:58404 "EHLO e31.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935126AbZLQBiA (ORCPT ); Wed, 16 Dec 2009 20:38:00 -0500 Subject: Re: [RFC][Patch] IBM Real-Time "SMI Free" mode drive -v2 From: john stultz To: Peter Zijlstra Cc: Keith Mannthey , lkml In-Reply-To: <1261004964.21028.521.camel@laptop> References: <1260907788.6521.10.camel@keith-laptop> <1261004964.21028.521.camel@laptop> Content-Type: text/plain; charset="UTF-8" Date: Wed, 16 Dec 2009 17:37:51 -0800 Message-ID: <1261013871.7245.21.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.28.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1976 Lines: 45 On Thu, 2009-12-17 at 00:09 +0100, Peter Zijlstra wrote: > On Tue, 2009-12-15 at 12:09 -0800, Keith Mannthey wrote: > > This driver supports the Real-Time Linux (RTL) BIOS feature. The RTL > > feature allows non-fatal System Management Interrupts (SMIs) to be > > disabled on supported IBM platforms. > > > > > > The Device is presented as a special "_rtl_" table to the OS in the > > Extended BIOS Data Area. There is a simple protocol for entering and > > exiting the mode at runtime. This driver creates a simple sysfs > > interface to allow a simple entry and exit from RTL mode in the > > UFI/BIOS. > > Why not simply always run with these non-fatal SMIs disabled and provide > their function through the OS proper? > > That way you don't need no silly switches and gain consistent platform > behaviour. Keith can probably correct me here if I'm wrong, but my understanding is that the SMIs provide hardware error detection, that while non-fatal are still important to the management of the system. The hardware may be used with other OSes or older Linux distros that do not provide a replacement for the SMI functionality. Further, disabling the SMIs can limit other features like power-throttling by the hardware, so its not something that can be always disabled in the hardware. So this driver provides a switch to allow the System to notify the hardware that the OS is capable of providing the error detection and is taking that responsibility over. The second piece required, which uses this interface to notify the BIOS its taking over this responsibility, is the ibm-prtmd daemon. This is the userland app that monitors the edac driver and sends the ipmi messages to the management module. thanks -john -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/