From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jonathan Creekmore Subject: Re: [PATCH v3 2/5] build: Hook the schedulers into Kconfig Date: Fri, 08 Jan 2016 11:04:56 -0600 Message-ID: References: <1452187761-38328-1-git-send-email-jonathan.creekmore@gmail.com> <1452187761-38328-3-git-send-email-jonathan.creekmore@gmail.com> <20160108154744.GE32260@char.us.oracle.com> <568FDBBA.8050103@citrix.com> <568FE00D.6080906@suse.com> <568FF6B102000078000C50CE@prv-mh.provo.novell.com> <568FEAD3.3040109@cardoe.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta4.messagelabs.com ([85.158.143.247]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1aHaTE-0002Gb-Ds for xen-devel@lists.xenproject.org; Fri, 08 Jan 2016 17:05:00 +0000 Received: by mail-yk0-f174.google.com with SMTP id k129so346314216yke.0 for ; Fri, 08 Jan 2016 09:04:59 -0800 (PST) In-reply-to: <568FEAD3.3040109@cardoe.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Doug Goldstein Cc: Juergen Gross , George Dunlap , Jonathan Creekmore , Dario Faggioli , Jan Beulich , Andrew Cooper , xen-devel@lists.xenproject.org List-Id: xen-devel@lists.xenproject.org Doug Goldstein writes: > On 1/8/16 10:49 AM, Jan Beulich wrote: >>>>> On 08.01.16 at 17:30, wrote: >>> So, based on the Kconfig setup and the linker ASSERT, there should be no >>> way to have a default scheduler that is not in the build. I wish Kconfig >>> allowed you to state that you must have at least one option selected or >>> up to all of the options selected (so I could require 1-4 schedulers >>> compiled in, but not 0). Unfortunately, the only way that seems allowed >>> is if you compile code in as modules, which Xen does not (with a choice >>> block, you can select multiple items as M, but only 1 as Y, but at least >>> 1 must be present --- since we only support Y, the choice block wouldn't >>> work for the schedulers). >> >> Perhaps credit should just not be configurable then? >> >> Jan >> > > How much effort are we willing to put in saving someone? We've already > got these options completely hidden away. We've already given the user a > warning that what they're doing isn't supported and they shouldn't be > touching this. Then they have to disable the scheduler that they pick as > the default. How many people are we expecting to really do this? I'm all > for idiot proofing things but at some point we've got to say there's > enough barriers to prevent this from happening. Otherwise we need to put > a Xen developer in every Xen users home or office. At this point, with the (not submitted yet) ASSERT in the linker file, it is a compile error to not have any schedulers linked in and Kconfig enforces that only schedulers compiled in can be a default.