From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr1-x435.google.com (mail-wr1-x435.google.com [IPv6:2a00:1450:4864:20::435]) by sourceware.org (Postfix) with ESMTPS id 368663858D39 for ; Sat, 27 Nov 2021 06:45:37 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 368663858D39 Received: by mail-wr1-x435.google.com with SMTP id s13so23382516wrb.3 for ; Fri, 26 Nov 2021 22:45:37 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=6+SsbLuwe/J2oZRCV3uG4KK9OJRcGatohNqceo6jSVs=; b=kpEeyQqZl4K4bt4anC+KhhLsnsqr3b75ZLfkih2h3jreHX9cRsextXG+l9LW/Jyv02 gy5i8RVHQri9VkyNaxJuSv3j9HNrMfAY5bOGbVmErhj3zM/MHm4JOP1r/6s/XGvBxekk mq1zn3UEPntEdqLSP+ymv5oVOVlFgL0VeyCgGWjps0FVmG1eBWrzEOexgbBdQUWXWlsA r4iA7i+BO2SmIxmKpML7C79UJn80KxhXRr/CN1Qz6hY/WrfgOOKrgOPgL/NAXktEFx/z tGRMdJz3Jd/n05CjXGT2EKqiIjrFRjYTIiAQecnYfkdVb5mxaNMlmRpN3IqUagzUm9GX 16OA== X-Gm-Message-State: AOAM533Ha2p1A7cHL2j0LGSCkD+BoL3a007SXcU/ojpld7rjLwXId61O 6zVL/6UU7GDYWm4DClJNKTnA X-Google-Smtp-Source: ABdhPJySc7ogg6jyv0uoHoEnp3ySFbNYXCHp0cAS/7c0qmCGWjicPe0ToknQm0qAq88TR42y0BVOjA== X-Received: by 2002:a05:6000:cd:: with SMTP id q13mr18961272wrx.488.1637995536256; Fri, 26 Nov 2021 22:45:36 -0800 (PST) Received: from takamaka.home ([2a01:cb22:1d5:1100:9ab1:6bb6:4b72:e905]) by smtp.gmail.com with ESMTPSA id h17sm13256004wmb.44.2021.11.26.22.45.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 26 Nov 2021 22:45:35 -0800 (PST) Received: by takamaka.home (Postfix, from userid 1000) id 0930EA4A80; Sat, 27 Nov 2021 10:45:33 +0400 (+04) Date: Sat, 27 Nov 2021 10:45:33 +0400 From: Joel Brobecker To: Jan Vrany via Gdb-patches Cc: lsix@lancelotsix.com, Jan Vrany , Joel Brobecker Subject: Re: [PATCH v2 1/2] ppc: use 'trap' ('tw, 31, 0, 0', 0x7fe00008) as breakpoint instruction Message-ID: References: <20211123154237.2335848-1-jan.vrany@labware.com> <20211124130926.2412617-1-jan.vrany@labware.com> <20211124130926.2412617-2-jan.vrany@labware.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211124130926.2412617-2-jan.vrany@labware.com> X-Spam-Status: No, score=-11.2 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 27 Nov 2021 06:45:38 -0000 Hi Jan, On Wed, Nov 24, 2021 at 01:09:25PM +0000, Jan Vrany via Gdb-patches wrote: > GDB used to use "tw 12, r2, r2" as a breakpoint instruction. While it > works, the PowerPC specifies 'tw, 31, 0, 0' (0x7fe00008) as the > canonical unconditional trap. > --- > gdb/rs6000-tdep.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/gdb/rs6000-tdep.c b/gdb/rs6000-tdep.c > index 87a494e0bb8..43880fa4426 100644 > --- a/gdb/rs6000-tdep.c > +++ b/gdb/rs6000-tdep.c > @@ -824,8 +824,8 @@ rs6000_fetch_pointer_argument (struct frame_info *frame, int argi, > > /* Sequence of bytes for breakpoint instruction. */ > > -constexpr gdb_byte big_breakpoint[] = { 0x7d, 0x82, 0x10, 0x08 }; > -constexpr gdb_byte little_breakpoint[] = { 0x08, 0x10, 0x82, 0x7d }; > +constexpr gdb_byte big_breakpoint[] = { 0x7f, 0xe0, 0x00, 0x08 }; > +constexpr gdb_byte little_breakpoint[] = { 0x08, 0x00, 0xe0, 0x7f }; > > typedef BP_MANIPULATION_ENDIAN (little_breakpoint, big_breakpoint) > rs6000_breakpoint; I'm going to say OK, but I'd like to know what your source is for this, so we can document that change. Part of me wonders why we're making a change like this one on some code which works, which is always a risk, no matter how small, unless we have enough evidence that this is going to be helpful in practice. Thank you, -- Joel