From owner-freebsd-hackers@FreeBSD.ORG Sat May 24 02:05:29 2014 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 9545D8D5 for ; Sat, 24 May 2014 02:05:29 +0000 (UTC) Received: from tds-solutions.net (tds-solutions.net [192.99.32.153]) by mx1.freebsd.org (Postfix) with ESMTP id 6DE172C2F for ; Sat, 24 May 2014 02:05:28 +0000 (UTC) Received: from tds-solutions.net (localhost [127.0.0.1]) by tds-solutions.net (Postfix) with ESMTP id 2F82AFED03 for ; Fri, 23 May 2014 22:05:19 -0400 (EDT) X-Virus-Scanned: amavisd-new at tds-solutions.net Received: from tds-solutions.net ([127.0.0.1]) by tds-solutions.net (tds-solutions.net [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id zBV3oNJWx88t for ; Fri, 23 May 2014 22:05:18 -0400 (EDT) Received: from [192.168.1.35] (24-177-51-95.dhcp.oxfr.ma.charter.com [24.177.51.95]) (Authenticated sender: sorressean) by tds-solutions.net (Postfix) with ESMTPSA id C58AEFECD3 for ; Fri, 23 May 2014 22:05:18 -0400 (EDT) Message-ID: <537FFE81.2080504@tysdomain.com> Date: Fri, 23 May 2014 22:05:53 -0400 From: "Littlefield, Tyler" Reply-To: tyler@tysdomain.com User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 MIME-Version: 1.0 To: "freebsd-hackers@freebsd.org" Subject: no SSE in kernel build? Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 24 May 2014 02:05:29 -0000 Hello all: I had a quick question I was hoping someone could explain for me. I was looking at some of the kernel source, just trying to familiarize myself with it. I notice that SSE, MMX and other such instruction sets are explicitly disabled during kernel compilation--is there any particular reason why? I'm sure it's pretty obvious, but my knowledge of kernel workings is pretty limited. I've seen functions like memset/memcpy that make use of SSE and are incredibly fast; perhaps this could be useful on architectures that support it? Finally, I'm interested in doing some performance work on the kernel--perhaps to help out somewhere. Is there anything at the kernel level a beginner could help out with? Where else might my help be useful? I know -some-, as I've worked a bit on a barebones OS, but I'm no means a kernel hacker. Thanks, -- Take care, Ty http://tds-solutions.net He that will not reason is a bigot; he that cannot reason is a fool; he that dares not reason is a slave.