Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932741AbXBONfp (ORCPT ); Thu, 15 Feb 2007 08:35:45 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932750AbXBONfp (ORCPT ); Thu, 15 Feb 2007 08:35:45 -0500 Received: from nf-out-0910.google.com ([64.233.182.189]:64111 "EHLO nf-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932741AbXBONfo (ORCPT ); Thu, 15 Feb 2007 08:35:44 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=SrG7Jh9xJ41mowv47VO3nen2WCesEKw3uaSnOva3LABOvQxJjG9ThknYEkH5Zuf23LiRwNXA+hYcQVAOx0hWtt7OvQ7diMfctinGIyEeje4eJg4lYRmG9mbTU+J6vTiH+ldbgZbTblzB98lkkaF+XT6oD1N1eByvIPN3a/49Te8= Message-ID: Date: Thu, 15 Feb 2007 08:35:42 -0500 From: "Dmitry Torokhov" To: "Rusty Russell" Subject: Re: [PATCH 9/11] Panic delay fix Cc: "Zachary Amsden" , "Linux Kernel Mailing List" , "Andrew Morton" , "Andi Kleen" , "Jeremy Fitzhardinge" , "Chris Wright" , Alan In-Reply-To: <1171493506.19842.179.camel@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <200702060353.l163rUmj000771@zach-dev.vmware.com> <1171493506.19842.179.camel@localhost.localdomain> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1231 Lines: 26 On 2/14/07, Rusty Russell wrote: > On Mon, 2007-02-05 at 19:53 -0800, Zachary Amsden wrote: > > Failure to use real-time delay here causes the keyboard to become demonically > > possessed in the event of a kernel crash, with wildly blinking lights and > > unpredictable behavior. This has resulted in several injuries. > > The problem is the normal one when we introduce a new concept into the > kernel; there are two kinds of udelay, and they've been conflated. The > most common case is a delay for real hardware devices; this can be > eliminated for paravirtualization. The other cases, the tiny minority, > are visible delays (keyboard leds), not knowing if they're necessary > (very early boot), and async events (other CPUs coming up): ie. > everything else. > Just for the record - I believe that i8042 is fine as is now. The only place where real delay needs to be enforced is panic.c - it should call panic blink routine once every 1 ms. -- Dmitry - 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/