Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753140Ab0ARHXp (ORCPT ); Mon, 18 Jan 2010 02:23:45 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752151Ab0ARHXo (ORCPT ); Mon, 18 Jan 2010 02:23:44 -0500 Received: from casper.infradead.org ([85.118.1.10]:35900 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751218Ab0ARHXn (ORCPT ); Mon, 18 Jan 2010 02:23:43 -0500 Subject: Re: [RFC] [PATCH 1/7] User Space Breakpoint Assistance Layer (UBP) From: Peter Zijlstra To: Jim Keniston Cc: Srikar Dronamraju , Ingo Molnar , Arnaldo Carvalho de Melo , Ananth N Mavinakayanahalli , utrace-devel , Frederic Weisbecker , Masami Hiramatsu , Maneesh Soni , Mark Wielaard , LKML In-Reply-To: <20100116184833.2s0zihwbggkgccsk@imap.linux.ibm.com> References: <20100116184833.2s0zihwbggkgccsk@imap.linux.ibm.com> Content-Type: text/plain; charset="UTF-8" Date: Mon, 18 Jan 2010 08:23:17 +0100 Message-ID: <1263799397.4283.2.camel@laptop> 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: 1081 Lines: 21 On Sat, 2010-01-16 at 18:48 -0500, Jim Keniston wrote: > As you may have noted before, I think FP would be a special problem > for your approach. I'm not sure how folks would react to the idea of > executing FP instructions in kernel space. But emulating them is also > tough. There's an IEEE FP emulation package somewhere in one of the > Linux arch directories, but I'm not sure how precise it is, and > dropping even 1 bit of precision is unacceptable for many > applications, since such errors tend to grow in complex computations > employing many FP instructions. Well, we have kernel space using FP/MMX/SSE like things, its not hard if you really need it, but in this case I think its easier than normal, because we'll just allow it to change the userspace state because that is exactly what we want it to do. -- 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/