From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by lists.ozlabs.org (Postfix) with ESMTP id 3s9pMv21sCzDr1m for ; Sat, 13 Aug 2016 01:14:50 +1000 (AEST) Subject: Re: debug problems on ppc 83xx target due to changed struct task_struct To: Holger Brunck , linuxppc-dev@lists.ozlabs.org References: Cc: mingo@kernel.org From: Dave Hansen Message-ID: <57ADE7E6.9030900@linux.intel.com> Date: Fri, 12 Aug 2016 08:14:46 -0700 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 08/12/2016 07:50 AM, Holger Brunck wrote: > When I try to debug our multithreaded userspace application with gdb I get > stuck when trying to single step code. Can you clarify "stuck"? Like the instructions don't advance? Have you been able to find a root cause for this? > Does anyone have an idea why the change in sched.h break my debug > usecase? Anyone out here who is debugging ppc83xx targets flawlessly > with a recent kernel? Thanks for going to the trouble of bisecting this, btw! I'd _suspect_ something very specific to your platform since this doesn't appear to affect even other ppc variants. I wonder if making it cross a page boundary from some other structure causes this, or moving it relative to something else. Could you try moving it to a few more places, or padding it by, say PAGE_SIZE on either side makes a difference? Is there some assembly involved in your single-stepping, or some other code that assumes relative offsets between two pieces of 'task_struct'?