From mboxrd@z Thu Jan 1 00:00:00 1970 From: "M. Koehrer" Subject: Triggering UserCode from KernelModule (IRQ) Date: Wed, 22 Apr 2009 16:14:48 +0200 (CEST) Message-ID: <6669682.1240409688443.JavaMail.ngmail@webmail19.ha2.local> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE To: linux-rt-users@vger.kernel.org Return-path: Received: from mail-in-04.arcor-online.net ([151.189.21.44]:45129 "EHLO mail-in-04.arcor-online.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750991AbZDVOOu convert rfc822-to-8bit (ORCPT ); Wed, 22 Apr 2009 10:14:50 -0400 Received: from mail-in-06-z2.arcor-online.net (mail-in-06-z2.arcor-online.net [151.189.8.18]) by mx.arcor.de (Postfix) with ESMTP id CD71E33AB13 for ; Wed, 22 Apr 2009 16:14:48 +0200 (CEST) Received: from mail-in-05.arcor-online.net (mail-in-05.arcor-online.net [151.189.21.45]) by mail-in-06-z2.arcor-online.net (Postfix) with ESMTP id C70E3ABAA8 for ; Wed, 22 Apr 2009 16:14:48 +0200 (CEST) Received: from webmail19.ha2.local (webmail19.arcor-online.net [151.189.8.77]) by mail-in-05.arcor-online.net (Postfix) with ESMTP id 73664332B7A for ; Wed, 22 Apr 2009 16:14:48 +0200 (CEST) Sender: linux-rt-users-owner@vger.kernel.org List-ID: Hi all! I am currently evaluting the RT_PREEMPT kernel as a replacement for a X= enomai based real time application. (Intel Core2Duo PCs). So far, everything works really fine and the performance is about the s= ame as with Xenomai. Great work! However, I have one question: I have a PCI hardware I/O board that exchanges data with the user mode=20 directly (by using mmap), this works fine. However, there is one operation mode that uses interrupts to signal inc= oming data. The interrupt handler is realized as a tiny kernel module (that one tha= t provides also=20 the mmap for the user mode application). Now I am not sure how the signalling of the IRQ from kernel to user mod= e could be realized=20 best (in terms of low latency). The "classical" approach for this task is to provide a character driver= with a .poll file operation. In Xenomai I could use a semaphore that was accessible from kernel and = user space for this. What is the best way in the RT_PREEMPT "world"?=20 Thanks a lot for all feedback on this question. Regards Mathias --=20 Mathias Koehrer mathias_koehrer@arcor.de Arcor.de Gaming Area - kostenfrei daddeln bis der Arzt kommt! Jetzt checken und aus =FCber 80 Spielen w=E4hlen! http://www.arcor.de/footer-gaming/ -- To unsubscribe from this list: send the line "unsubscribe linux-rt-user= s" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html