From owner-freebsd-ppc@FreeBSD.ORG Fri May 1 01:11:39 2009 Return-Path: Delivered-To: freebsd-ppc@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 4BC98106566C for ; Fri, 1 May 2009 01:11:39 +0000 (UTC) (envelope-from xcllnt@mac.com) Received: from asmtpout017.mac.com (asmtpout017.mac.com [17.148.16.92]) by mx1.freebsd.org (Postfix) with ESMTP id 36C128FC1A for ; Fri, 1 May 2009 01:11:39 +0000 (UTC) (envelope-from xcllnt@mac.com) MIME-version: 1.0 Content-transfer-encoding: 7BIT Content-type: text/plain; charset=us-ascii; format=flowed; delsp=yes Received: from [10.80.166.237] (mobile-032-152-155-038.mycingular.net [32.152.155.38]) by asmtp017.mac.com (Sun Java(tm) System Messaging Server 6.3-8.01 (built Dec 16 2008; 32bit)) with ESMTPSA id <0KIX005APXZ7AJ40@asmtp017.mac.com> for freebsd-ppc@freebsd.org; Thu, 30 Apr 2009 18:11:39 -0700 (PDT) References: <36D74D0F-DB5D-4B3D-8A34-2AC72A5209AF@semihalf.com> Message-id: <9904FBD1-F01A-4E7C-9E71-6C2D544352F8@mac.com> From: Marcel Moolenaar To: Rafal Jaworowski In-reply-to: Date: Thu, 30 Apr 2009 18:09:59 -0700 X-Mailer: iPhone Mail (5H11) Cc: "freebsd-ppc@freebsd.org" Subject: Re: Single stepping through atomic ops X-BeenThere: freebsd-ppc@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Porting FreeBSD to the PowerPC List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 01 May 2009 01:11:39 -0000 Sorry for the delay... There's an effort to import GDB 6.4 I think. What's the version of GDB that is fixed? -- Marcel On Apr 30, 2009, at 2:01 AM, Rafal Jaworowski wrote: > > On 2009-04-21, at 19:57, Rafal Jaworowski wrote: > >> Hi Marcel, >> I'm writing to you primarily as the gdb maintainer :-) There's a >> problem with current gdb in base when single stepping through >> atomic sequences on PowerPC (and presumably other archs with the >> load + conditional store approach for atomic ops). The effect is a >> hang because we endlessly loop due to the [always] lost reservation >> at the time of a closing stwcx. >> >> This is a known problem with gdb and it's fixed with newer >> versions, but the patches are not applicable to our gdb due to some >> infrastructure changes. The quick fix for 6.1.1 is here: >> http://people.freebsd.org/~raj/patches/powerpc/gdb-ppc-single-step.diff >> >> It's mainly a transplant of two fixes from the gdb repository >> (1.275, 1.276, deal_with_atomic_sequence) adjusted to our older gdb >> code, but it's ugly #ifdef'ed __ppc__. In order to do it cleanly we >> would need to change the signature of the SOFTWARE_SINGLE_STEP >> method so it returns a value (this is how newer gdb works), but it >> would affect gdb for all architectures. Do you see any objections >> for growing a return value here? >> >> Another direction would be importing a newer gdb code base, and be >> able to apply the fixes directly and cleanly (if at all required), >> but am not sure if there are any plans to upgrade gdb in base? Let >> me know your comments. > > Have you got any comments to this? Should I move on and commit this > as ugly as is, or would reworking SOFTWARE_SINGLE_STEP be more > desired? Any thoughts about newer gdb versions coming to the tree? > > Rafal >