From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 3339 invoked by alias); 26 Oct 2007 01:51:22 -0000 Received: (qmail 3327 invoked by uid 22791); 26 Oct 2007 01:51:21 -0000 X-Spam-Check-By: sourceware.org Received: from gate.crashing.org (HELO gate.crashing.org) (63.228.1.57) by sourceware.org (qpsmtpd/0.31) with ESMTP; Fri, 26 Oct 2007 01:51:20 +0000 Received: from [127.0.0.1] (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.13.8/8.13.8) with ESMTP id l9Q1ouHH001380; Thu, 25 Oct 2007 20:50:57 -0500 Subject: Re: Apparent kernel bug with GDB on ppc405 From: Benjamin Herrenschmidt Reply-To: benh@kernel.crashing.org To: Grant Likely Cc: Matt Mackall , gdb@sourceware.org, linuxppc-embedded@ozlabs.org In-Reply-To: References: <20071024194640.GB19691@waste.org> <20071024204215.GC19691@waste.org> <20071024215421.GF19691@waste.org> <20071024223250.GI19691@waste.org> Content-Type: text/plain Date: Fri, 26 Oct 2007 01:51:00 -0000 Message-Id: <1193363453.7018.38.camel@pasglop> Mime-Version: 1.0 X-Mailer: Evolution 2.12.0 Content-Transfer-Encoding: 7bit Mailing-List: contact gdb-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-owner@sourceware.org X-SW-Source: 2007-10/txt/msg00251.txt.bz2 On Wed, 2007-10-24 at 16:40 -0600, Grant Likely wrote: > On 10/24/07, Grant Likely wrote: > > > Not completely implausible, but a) why isn't this seen on basically > > > every machine with software TLB? b) why does -local- GDB, which is > > > presumably doing much less work than gdbserver + network stack, not fail? > > > > a) I don't know.... very odd. > > > > b) gdb is big. It probably touches far more pages (via library calls) > > than gdbserver. The network stack is also big, but it's probably more > > localized too. > > > > Niceing down the host also makes sense because if the PC is being slow > > then the target may go off and run other things while between setting > > the breakpoint and getting the 'go' command. > > > > Can you grab a snapshot of the TLB before and after setting the breakpoint? > > Or; probably more relevant, before and after the page copy? COW does ptep_clear_flush before setting the new TLB which does a flush_tlb_page() so that should work. Ben.