Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751269AbWIYRFp (ORCPT ); Mon, 25 Sep 2006 13:05:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751280AbWIYRFp (ORCPT ); Mon, 25 Sep 2006 13:05:45 -0400 Received: from [212.227.126.187] ([212.227.126.187]:3791 "EHLO moutng.kundenserver.de") by vger.kernel.org with ESMTP id S1751269AbWIYRFo (ORCPT ); Mon, 25 Sep 2006 13:05:44 -0400 From: Arnd Bergmann To: Aubrey Subject: Re: [PATCH 1/4] Blackfin: arch patch for 2.6.18 Date: Mon, 25 Sep 2006 19:05:21 +0200 User-Agent: KMail/1.9.4 Cc: "Luke Yang" , linux-kernel@vger.kernel.org, "Andrew Morton" References: <489ecd0c0609202032l1c5540f7t980244e30d134ca0@mail.gmail.com> <200609251126.17494.arnd@arndb.de> <6d6a94c50609250839y7365e20ale6910e36b0ec9976@mail.gmail.com> In-Reply-To: <6d6a94c50609250839y7365e20ale6910e36b0ec9976@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200609251905.22224.arnd@arndb.de> X-Provags-ID: kundenserver.de abuse@kundenserver.de login:c48f057754fc1b1a557605ab9fa6da41 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1310 Lines: 41 On Monday 25 September 2006 17:39, Aubrey wrote: > 1) Timer interrupt will call do_irq(), then return_from_int(). > > 2) return_from_int() will check if there is interrupt pending or > signal pending, if so, it will call schedule_and_signal_from_int(). > > 3) schedule_and_signal_from_int() will jump to resume_userspace() > > 4) resume_userspace() will call _schedule to run the user task. I have a little trouble reading your assembly code, but your return_from_int() function should normally not call schedule_and_signal_from_int() when the interrupt happened in kernel context (like in the idle function): + /* if not return to user mode, get out */ + p2.l = lo(IPEND); + p2.h = hi(IPEND); + r0 = [p2]; + r1 = 0x17(Z); + r2 = ~r1; + r2.h = 0; + r0 = r2 & r0; + r1 = 1; + r1 = r0 - r1; + r2 = r0 & r1; + cc = r2 == 0; + if !cc jump 2f; This looks a lot like you user_mode() function, so you jump over schedule_and_signal_from_int() here. What you described would be a preemptive kernel (CONFIG_PREEMPT), but you clearly don't have that enabled. Arnd <>< - 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/