From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Wed, 17 Oct 2007 18:23:48 +0100 (BST) Received: from localhost.localdomain ([127.0.0.1]:41368 "EHLO dl5rb.ham-radio-op.net") by ftp.linux-mips.org with ESMTP id S20038915AbXJQRXq (ORCPT ); Wed, 17 Oct 2007 18:23:46 +0100 Received: from denk.linux-mips.net (denk.linux-mips.net [127.0.0.1]) by dl5rb.ham-radio-op.net (8.14.1/8.13.8) with ESMTP id l9HHNj0s008858; Wed, 17 Oct 2007 18:23:45 +0100 Received: (from ralf@localhost) by denk.linux-mips.net (8.14.1/8.14.1/Submit) id l9HHNjoP008857; Wed, 17 Oct 2007 18:23:45 +0100 Date: Wed, 17 Oct 2007 18:23:45 +0100 From: Ralf Baechle To: "Maciej W. Rozycki" Cc: Atsushi Nemoto , linux-mips@linux-mips.org Subject: Re: [MIPS] Probe for usability of cp0 compare interrupt. Message-ID: <20071017172345.GA7313@linux-mips.org> References: <20071018.011033.115643462.anemo@mba.ocn.ne.jp> <20071017164636.GC5491@linux-mips.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.14 (2007-02-12) Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 17102 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: ralf@linux-mips.org Precedence: bulk X-list: linux-mips On Wed, Oct 17, 2007 at 06:03:35PM +0100, Maciej W. Rozycki wrote: > > The two things are a know lose end. There is a bug in some old MIPS > > processors where reading one of the compare or count registers in exactly > > the moment when both have identical values in the interrupt getting lost. > > > > Will have to dig up the details on that one again before I can implement > > a proper workaround ... > > This is the erratum #53 of the R4000PC/SC processor and it triggers if > the Count register is read. Conveniently, in the errata sheet as > distributed, the text is covered by a figure (Figure 1a on page 13), so > you can only reach the page with some PostScript magic. I did it a while > ago and now have a separate document available which provides the text of > page 13 with the figure removed. I can provide it if there is interest. Ah. I noticed there was something like white writing on white background matching when I searched the PDF for keywords. So I guess it would be nice if somebody could regenerate a PS or PDF file. I also seem to be missing information on the later R4400 versions. Ralf