From mboxrd@z Thu Jan 1 00:00:00 1970 Received: by oss.sgi.com id ; Tue, 9 Jan 2001 10:39:16 -0800 Received: from brutus.conectiva.com.br ([200.250.58.146]:19962 "EHLO lappi.waldorf-gmbh.de") by oss.sgi.com with ESMTP id ; Tue, 9 Jan 2001 10:39:03 -0800 Received: (ralf@lappi.waldorf-gmbh.de) by bacchus.dhis.org id ; Tue, 9 Jan 2001 16:28:35 -0200 Date: Tue, 9 Jan 2001 16:28:35 -0200 From: Ralf Baechle To: Harald Koerfgen Cc: linux-mips@oss.sgi.com Subject: Re: MIPS32 patches breaking DecStation Message-ID: <20010109162835.B4232@bacchus.dhis.org> References: <20010109095438.A10683@paradigm.rfc822.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: ; from Harald.Koerfgen@home.ivm.de on Tue, Jan 09, 2001 at 06:11:00PM +0100 X-Accept-Language: de,en,fr Sender: owner-linux-mips@oss.sgi.com Precedence: bulk Return-Path: X-Orcpt: rfc822;linux-mips-outgoing On Tue, Jan 09, 2001 at 06:11:00PM +0100, Harald Koerfgen wrote: > > No problem - Done - doesnt work > > Same here on my /260 (R4400SC V4.0). Neither inserting four "sll $0,$0,1" nor > four "nop" seem to work. The branch, on the other hand, does. Note the ssnops only make sense on superscalar CPUs, so not on the R4000. Also note that the branch is equivalent to three nops. One for the branch instruction itself, the two more for instructions in the pipeline that get killed. On the R4600 / R500 where the hazard is only a single instruction the branch is equivalent to only a single nop. So while unobvious the branch is a rather neat idea. Ralf