Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261216AbVEIK6i (ORCPT ); Mon, 9 May 2005 06:58:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261238AbVEIK6i (ORCPT ); Mon, 9 May 2005 06:58:38 -0400 Received: from general.keba.co.at ([193.154.24.243]:54743 "EHLO helga.keba.co.at") by vger.kernel.org with ESMTP id S261216AbVEIK6g convert rfc822-to-8bit (ORCPT ); Mon, 9 May 2005 06:58:36 -0400 X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 Content-class: urn:content-classes:message MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 8BIT Subject: Real-Time Preemption: Magic Sysrq p doesn't work Date: Mon, 9 May 2005 12:58:34 +0200 Message-ID: X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: Real-Time Preemption: Magic Sysrq p doesn't work Thread-Index: AcVUd/147/EWgvWnQiax74qDHXJcJwAC5w8w From: "kus Kusche Klaus" To: "Ingo Molnar" Cc: , Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1400 Lines: 33 While testing, I noticed that Sysrq p is silently ignored on current RT kernels with RT preemption: The syslog contains a message that Sysrq p was pressed, but no registers are printed. A vanilla 2.6.11 with the same config (except for the RT-specific settings) on the same hardware (i386) gives correct Sysrq p output. The keyboard is connected via USB. I checked the code: The sysrq p function is passed a "struct pt_regs *" arg, and only produces output if this pointer is non-NULL. For RT kernels, it is always NULL (I added a printk). This "struct pt_regs *" travels all the way from the actual keyboard interrupt handler (it is passed as an arg to "usb_kbd_irq"), but I was not able to trace it back any further in the source. Is this a known problem? Is there any workaround? (Sysrq p would be very helpful for debugging!) Thanks in advance for any hints! -- Klaus Kusche (Software Development - Control Systems) KEBA AG Gewerbepark Urfahr, A-4041 Linz, Austria (Europe) Tel: +43 / 732 / 7090-3120 Fax: +43 / 732 / 7090-6301 E-Mail: kus@keba.com WWW: www.keba.com - 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/