Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751468AbXBOBBJ (ORCPT ); Wed, 14 Feb 2007 20:01:09 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751475AbXBOBBJ (ORCPT ); Wed, 14 Feb 2007 20:01:09 -0500 Received: from x35.xmailserver.org ([64.71.152.41]:3895 "EHLO x35.xmailserver.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751468AbXBOBBH (ORCPT ); Wed, 14 Feb 2007 20:01:07 -0500 X-AuthUser: davidel@xmailserver.org Date: Wed, 14 Feb 2007 17:01:04 -0800 (PST) From: Davide Libenzi X-X-Sender: davide@alien.or.mcafeemobile.com To: Ingo Molnar cc: Alan , Linus Torvalds , Linux Kernel Mailing List , Arjan van de Ven , Christoph Hellwig , Andrew Morton , Ulrich Drepper , Zach Brown , Evgeniy Polyakov , "David S. Miller" , Benjamin LaHaise , Suparna Bhattacharya , Thomas Gleixner Subject: Re: [patch 05/11] syslets: core code In-Reply-To: <20070214223216.GA7616@elte.hu> Message-ID: References: <20070213142035.GF638@elte.hu> <20070214210251.GA15025@elte.hu> <20070214215613.56d76257@localhost.localdomain> <20070214223216.GA7616@elte.hu> X-GPG-FINGRPRINT: CFAE 5BEE FD36 F65E E640 56FE 0974 BF23 270F 474E X-GPG-PUBLIC_KEY: http://www.xmailserver.org/davidel.asc MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1227 Lines: 29 On Wed, 14 Feb 2007, Ingo Molnar wrote: > yeah, that's another key thing. I do plan to provide a sys_upcall() > syscall as well which calls a 5-parameter user-space function with a > special stack. (it's like a lightweight signal/event handler, without > any of the signal handler legacies and overhead - it's like a reverse > system call - a "user call". Obviously pure userspace would never use > sys_upcall(), unless as an act of sheer masochism.) That is exactly what I described as clets. Instead of having complex jump and condition interpreters on the kernel (on top of new syscalls to modify/increment userspace variables), you just code it in C and you pass the clet pointer to the kernel. The upcall will setup a frame, execute the clet (where jump/conditions and userspace variable changes happen in machine code - gcc is pretty good in taking care of that for us) on its return, come back through a sys_async_return, and go back to userspace. - Davide - 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/