From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-out.m-online.net (mail-out.m-online.net [212.18.0.10]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 341842C00F8 for ; Sun, 27 Oct 2013 21:26:22 +1100 (EST) To: Kumar Gala From: Wolfgang Denk Subject: Re: [PATCH] [RFC] Emulate "lwsync" to run standard user land on e500 cores MIME-Version: 1.0 Content-type: text/plain; charset=UTF-8 In-reply-to: <6BFC8EB0-1A75-41C3-985A-E3ED14846710@kernel.crashing.org> References: <1382081880-6666-1-git-send-email-wd@denx.de> <39CCEB38-1D9B-4918-B8F4-148D4E90FE21@kernel.crashing.org> <1382523314.3926.21.camel@aoeu.buserror.net> <1382607919.9395.56.camel@pasglop> <6BFC8EB0-1A75-41C3-985A-E3ED14846710@kernel.crashing.org> Date: Sun, 27 Oct 2013 11:25:53 +0100 Message-Id: <20131027102554.06B313811DD@gemini.denx.de> Cc: Scott Wood , linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Dear Kumar, In message <6BFC8EB0-1A75-41C3-985A-E3ED14846710@kernel.crashing.org> you wrote: > > Fair enough > > > > I'm not too worried as long as we warn and account them. > > Than, I'd ask this be under a Kconfig option that is disabled by > default. Users should have to explicitly enable this so they know what > they are doing. Is this really worth the effort? Under normal situations (users are using a user space environment that has been properly buiult for the processor variant they are using) nobody should ever run into this situation. It happens only if you are already doing something wrong - like using user space that has not been built for an E500 core on such a machine. In this situation, it seems more useful to me if a "standard" kernel just works with a "standard" user space environment, even if this includes some performance penalty - which actually should be neglibale. In my tests (when running standard Debian for PPC on a E500 only very few programs actually triggered this situation, and none of them in a time-critical way. I doubt I would even be able to measure the performance impact. Best regards, Wolfgang Denk -- DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd@denx.de "...all the good computer designs are bootlegged; the formally planned products, if they are built at all, are dogs!" - David E. Lundstrom, "A Few Good Men From Univac", MIT Press, 1987