From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Tue, 17 Sep 2013 10:42:08 +0200 (CEST) Received: from elvis.franken.de ([193.175.24.41]:44988 "EHLO elvis.franken.de" rhost-flags-OK-OK-OK-OK) by eddie.linux-mips.org with ESMTP id S6816642Ab3IQImEyEUlE (ORCPT ); Tue, 17 Sep 2013 10:42:04 +0200 Received: from uucp (helo=solo.franken.de) by elvis.franken.de with local-bsmtp (Exim 3.36 #1) id 1VLqrE-0006pl-00; Tue, 17 Sep 2013 10:42:04 +0200 Received: by solo.franken.de (Postfix, from userid 1000) id ADFD45B90C7; Tue, 17 Sep 2013 10:41:26 +0200 (CEST) Date: Tue, 17 Sep 2013 10:41:26 +0200 From: Thomas Bogendoerfer To: "Maciej W. Rozycki" Cc: Ralf Baechle , linux-mips@linux-mips.org Subject: Re: [PATCH] MIPS: DECstation HRT calibration bug fixes Message-ID: <20130917084126.GA9785@alpha.franken.de> References: <20130905180825.GB11592@linux-mips.org> <20130907073450.GE11592@linux-mips.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) 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: 37825 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: tsbogend@alpha.franken.de Precedence: bulk List-help: List-unsubscribe: List-software: Ecartis version 1.0.0 List-Id: linux-mips X-List-ID: linux-mips List-subscribe: List-owner: List-post: List-archive: X-list: linux-mips On Mon, Sep 16, 2013 at 06:54:55AM +0100, Maciej W. Rozycki wrote: > Thomas, what was the rationale behind arranging things in this way? Did > you mean to make this code shared among platforms needing it? I would I really can't remember the reasoning any more, but I guess code sharing was a reason. > guess so, but then the copy in arch/mips/dec/prom/ would have to be > removed and macros in adjusted according to the new API > which you didn't do in your change. because I didn't have a running DECstation handy. > Also why the need for stack > switching? It looks like an unnecessary complication to me, any firmware > callbacks exported have to maintain stack integrity or they would be > unusable. Is that to work around some SNI firmware quirk? a 64bit kernel with more than CKSEG0 addressable memory may end up having a stack outside of CKSEG0, which is something the 32bit SNI firmware doesn't like. I guess the same is true for DECstation, if there is a HW config with enough memory. > [And does it work for the SNI in the first place? -- it looks to me like > `o32_stk' has an alignment problem (8 is required for the stack pointer in > the o32 ABI though 4 will often be enough to satisfy hardware); but > perhaps it just happens to get correct alignment by virtue of merely > always following a data object that enforces it, hmm...] it worked, but nevertheless fixing the aligment isn't a bad thing. Thomas. -- Crap can work. Given enough thrust pigs will fly, but it's not necessarily a good idea. [ RFC1925, 2.3 ]