From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264955AbUFRCYQ (ORCPT ); Thu, 17 Jun 2004 22:24:16 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264961AbUFRCYQ (ORCPT ); Thu, 17 Jun 2004 22:24:16 -0400 Received: from ns1.lanforge.com ([66.165.47.210]:57294 "EHLO www.lanforge.com") by vger.kernel.org with ESMTP id S264955AbUFRCYO (ORCPT ); Thu, 17 Jun 2004 22:24:14 -0400 Message-ID: <40D25247.3050509@candelatech.com> Date: Thu, 17 Jun 2004 19:24:07 -0700 From: Ben Greear Organization: Candela Technologies User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.6) Gecko/20040113 X-Accept-Language: en-us, en MIME-Version: 1.0 To: root@chaos.analogic.com CC: Linux kernel Subject: Re: poll References: <40D21C8E.4040500@candelatech.com> In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Richard B. Johnson wrote: > On Thu, 17 Jun 2004, Ben Greear wrote: > > >>Richard B. Johnson wrote: >> >>>Hello, >>>Is it okay to use the 'extra' bits in the poll return value for >>>something? In other words, is the kernel going to allow a user-space >>>program to define some poll-bits that it waits for, these bits >>>having been used in the driver? >> >>Can't you just do a read and determine from the results of the read >>what you actually got? If not, add framing to your message so that >>you *CAN* determine one message type from another... >> >>Ben >> > > > The mailbox read(s) is/are 32-bit int(s). There is no way to identify > it as being "new" or something that was written two weeks ago. > That's why we use poll. Poll says 'I got something new for you'. Then use 3 different file descriptors to poll/read. That seems more efficient anyway as it doesn't wake the folks who don't care. Ben -- Ben Greear Candela Technologies Inc http://www.candelatech.com