From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 17126 invoked by alias); 10 Sep 2012 16:56:07 -0000 Received: (qmail 17112 invoked by uid 22791); 10 Sep 2012 16:56:04 -0000 X-SWARE-Spam-Status: No, hits=-5.1 required=5.0 tests=AWL,BAYES_00,DKIM_SIGNED,DKIM_VALID,FREEMAIL_FROM,KHOP_RCVD_TRUST,KHOP_THREADED,RCVD_IN_DNSWL_LOW,RCVD_IN_HOSTKARMA_YE X-Spam-Check-By: sourceware.org Received: from mail-vc0-f169.google.com (HELO mail-vc0-f169.google.com) (209.85.220.169) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Mon, 10 Sep 2012 16:55:50 +0000 Received: by vcbfl13 with SMTP id fl13so2051217vcb.0 for ; Mon, 10 Sep 2012 09:55:49 -0700 (PDT) Received: by 10.220.107.146 with SMTP id b18mr13447273vcp.48.1347296149718; Mon, 10 Sep 2012 09:55:49 -0700 (PDT) MIME-Version: 1.0 Received: by 10.58.164.66 with HTTP; Mon, 10 Sep 2012 09:55:29 -0700 (PDT) In-Reply-To: <504E0877.2040202@redhat.com> References: <87zk4yxjyr.fsf@redhat.com> <504E0877.2040202@redhat.com> From: Mike Frysinger Date: Mon, 10 Sep 2012 16:56:00 -0000 Message-ID: Subject: Re: RFA: V850 sim: various fixes. To: nick clifton Cc: dj@redhat.com, gdb-patches@sourceware.org Content-Type: text/plain; charset=ISO-8859-1 X-IsSubscribed: yes Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org X-SW-Source: 2012-09/txt/msg00123.txt.bz2 On Mon, Sep 10, 2012 at 8:34 AM, nick clifton wrote: >>> It also adds a snippet of code to catch attempts to >>> execute code via a NULL pointer. >> >> usually the simulator represents the hardware. so if the hardware has >> memory at address 0 and someone were to load up an image with code >> there, there's nothing invalid when it comes to jumping there. > > Personally I see the simulator as more of a testing and debugging tool. It > does not try to be hardware accurate - it does not model the cache for > example - so adding a feature that helps catch program errors, even if it > not strictly modelling the hardware, seems OK to me. well, you're talking about cycle accurate simulators vs functional accurate simulators. yes, many sims don't model down to the cache level (although that functionality is available), nor things like the pipeline, but at a functional level, those don't matter. being able to read/write/execute address 0 is a functional aspect. i'm not against adding a flag to control this, but in general i don't think completely blocking a functional aspect is correct ... although DJ is the v850 guy, and i certainly won't force this policy on every sim since not everyone uses the sim as a generically as i do. -mike