From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 10595 invoked by alias); 12 May 2015 15:14:33 -0000 Mailing-List: contact binutils-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: binutils-owner@sourceware.org Received: (qmail 10512 invoked by uid 89); 12 May 2015 15:14:32 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.4 required=5.0 tests=AWL,BAYES_00,KAM_LAZY_DOMAIN_SECURITY,T_RP_MATCHES_RCVD autolearn=no version=3.3.2 X-HELO: mx2.suse.de Received: from cantor2.suse.de (HELO mx2.suse.de) (195.135.220.15) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (CAMELLIA256-SHA encrypted) ESMTPS; Tue, 12 May 2015 15:14:31 +0000 Received: from relay1.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 469AAAAF2; Tue, 12 May 2015 15:14:28 +0000 (UTC) Date: Tue, 12 May 2015 15:14:00 -0000 From: Michael Matz To: "H.J. Lu" cc: Jan Beulich , Binutils Subject: Re: [committed, PATCH] Remove Disp16|Disp32 from 64-bit direct branches In-Reply-To: Message-ID: References: <20150511212331.GA1838@intel.com> <5551F4E70200007800079575@mail.emea.novell.com> <55520C440200007800079718@mail.emea.novell.com> <555216370200007800079773@mail.emea.novell.com> User-Agent: Alpine 2.20 (LSU 67 2015-01-07) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-IsSubscribed: yes X-SW-Source: 2015-05/txt/msg00093.txt.bz2 Hi, On Tue, 12 May 2015, H.J. Lu wrote: > >> 2. Can you speculate what > >> > >> " jmpw 4" > >> > >> does? > > > > It should do a jump to $nextip+offset, of course, just like a 32bit > > jump. The disassembly is correct, because with a zero offset, that's > > indeed '4'. > > I thought it did jump to "(nextip + offset) & 0xffff" on AMD. Can you > verify if it is true? Sorry, yes, this is true, the 16bit operand size prefix truncates RIP to 16 bit. Nevertheless it's a valid instruction and works as documented. Ciao, Michael.