From owner-svn-src-projects@FreeBSD.ORG Sun Dec 16 17:18:54 2012 Return-Path: <owner-svn-src-projects@FreeBSD.ORG> Delivered-To: svn-src-projects@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 9A053EA1; Sun, 16 Dec 2012 17:18:54 +0000 (UTC) (envelope-from adrian.chadd@gmail.com) Received: from mail-wi0-f174.google.com (mail-wi0-f174.google.com [209.85.212.174]) by mx1.freebsd.org (Postfix) with ESMTP id CFDDF8FC0A; Sun, 16 Dec 2012 17:18:53 +0000 (UTC) Received: by mail-wi0-f174.google.com with SMTP id hm9so1467506wib.13 for <multiple recipients>; Sun, 16 Dec 2012 09:18:52 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type; bh=0LjH8PexIh6W5vQZXvE+AtYONzpXqJOU9zdr91b17fc=; b=WTH6/dzxCH5fi7yD/4vulULBCjnEboJUjIPCcw0/W8uBx/1TUnkNxPgNuAv5TOqx5l zPFuyhR3AGFUt7itZnHnLG+MhaYcQzThzdZ5afpyA9bva+a3y4d2F2EAqn9UbxZ3XjbF LyF/kEXWlwfi0oleX41paq243EhmzMsMA22JkdBVx3+TCwGpLUg/knoqyESpOhkUnynC 9lFnsegavrAe1m534UOOtzkgjfK9pkcqIGILGNz4jzeUij9wrXH87fTUoDhCRrVB1zXB xkLD6fJOjD9Fl22Z7rBammVtIzpJyT+vmfGe1hADMavXDRsTK5hhwZGKvLC+a9cnGDhb R2Yw== MIME-Version: 1.0 Received: by 10.194.179.34 with SMTP id dd2mr12960139wjc.1.1355678330965; Sun, 16 Dec 2012 09:18:50 -0800 (PST) Sender: adrian.chadd@gmail.com Received: by 10.217.57.9 with HTTP; Sun, 16 Dec 2012 09:18:50 -0800 (PST) In-Reply-To: <50CE009B.7010804@FreeBSD.org> References: <201212161116.qBGBGEwn063983@svn.freebsd.org> <CAJ-VmonYuh4dTwY9PjBmE4uOq8nNAL_kDKXpi6knwvc99PqJcw@mail.gmail.com> <50CE009B.7010804@FreeBSD.org> Date: Sun, 16 Dec 2012 09:18:50 -0800 X-Google-Sender-Auth: kg6k0cjK6XZNeq7snQzydF8ZAEE Message-ID: <CAJ-Vmok7rdooCifWmNw2LJ95BSuOwwz6wPeq86x8AcAp7FzuJw@mail.gmail.com> Subject: Re: svn commit: r244287 - projects/calloutng/sys/x86/isa From: Adrian Chadd <adrian@freebsd.org> To: Alexander Motin <mav@freebsd.org> Content-Type: text/plain; charset=ISO-8859-1 Cc: svn-src-projects@freebsd.org, src-committers@freebsd.org X-BeenThere: svn-src-projects@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: "SVN commit messages for the src " projects" tree" <svn-src-projects.freebsd.org> List-Unsubscribe: <http://lists.freebsd.org/mailman/options/svn-src-projects>, <mailto:svn-src-projects-request@freebsd.org?subject=unsubscribe> List-Archive: <http://lists.freebsd.org/pipermail/svn-src-projects> List-Post: <mailto:svn-src-projects@freebsd.org> List-Help: <mailto:svn-src-projects-request@freebsd.org?subject=help> List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/svn-src-projects>, <mailto:svn-src-projects-request@freebsd.org?subject=subscribe> X-List-Received-Date: Sun, 16 Dec 2012 17:18:54 -0000 On 16 December 2012 09:10, Alexander Motin <mav@freebsd.org> wrote: > This change affects only one-shot operation mode of i8254 eventtimer, which > we can't enable by default because it can't coexist with i8254 timecounter, > which we can't disable by default because we can't be sure that there is any > other timecounter. That is why I've written about fun. And no, I have no > all possible weird i8254 clones to test, so any help and ideas are welcome. > :) That's why I think you guys have to be very careful here. There's still plenty of embedded x86 hardware out there which uses not-quite-matching i8254 silicon implementations. I realise it's not enabled by default, but by putting this code in there, you risk having it eventually bubble up and become potentially available/active on some quirky embedded platforms (or heck, non-embedded platforms where for some reason the i8254 eventtimer is active, but the timecounter isn't.) The point I'm trying to make here is that you guys shouldn't just change things because you don't think that it'll not be used. You may not think it's being used but the whole i386 space (embedded or otherwise) is full of legacy (and non-legacy) hilarity. You should be really careful that you don't break previous things which you just don't have a chance in hell of being able to test thoroughly. We have 15 years of "mostly working" on a really really quirky platform. You won't get that kind of testing again. I'm (kind of) sorry for being overly serious and ranty here - but this is exactly the kind of thing that breaks hardware support in unpredictable ways, making us all look bad. Adrian