From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andreas Schwab Subject: Re: m68k, signals and single-stepping Date: Thu, 30 Sep 2010 10:21:47 +0200 Message-ID: References: <20100930055823.GK19804@ZenIV.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-out.m-online.net ([212.18.0.10]:47640 "EHLO mail-out.m-online.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750972Ab0I3IVu (ORCPT ); Thu, 30 Sep 2010 04:21:50 -0400 In-Reply-To: (Geert Uytterhoeven's message of "Thu, 30 Sep 2010 08:07:05 +0200") Sender: linux-m68k-owner@vger.kernel.org List-Id: linux-m68k@vger.kernel.org To: Geert Uytterhoeven Cc: Al Viro , Linux/m68k Geert Uytterhoeven writes: >> So what's that SIGTRAP on exit from syscall in single-stepping mode for? The trace exception is low priority exception that is executed after all other exceptions are processed. So if the cpu single steps over a trap insns, the trace exception processing is started when the trap exception processing is complete, which is just before the cpu starts executing the trap exception handler in the kernel. You want the SIGTRAP to be sent to the user process, so you have to delay sending it until the kernel returns to user space. Andreas. -- Andreas Schwab, schwab@linux-m68k.org GPG Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5 "And now for something completely different."