Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755278Ab2HNMuM (ORCPT ); Tue, 14 Aug 2012 08:50:12 -0400 Received: from relay4-d.mail.gandi.net ([217.70.183.196]:43529 "EHLO relay4-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754686Ab2HNMuK (ORCPT ); Tue, 14 Aug 2012 08:50:10 -0400 X-Originating-IP: 217.70.178.146 X-Originating-IP: 50.43.46.74 Date: Tue, 14 Aug 2012 05:50:03 -0700 From: Josh Triplett To: Josh Boyer Cc: Randy Dunlap , Thai Bui , Konrad Rzeszutek Wilk , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/1] boot: Put initcall_debug into its own Kconfig option DEBUG_INITCALL Message-ID: <20120814125002.GA8125@leaf> References: <1344891431-30869-1-git-send-email-blquythai@gmail.com> <20120813212151.GA15429@phenom.dumpdata.com> <5029823A.9020207@xenotime.net> <20120814011826.GA2255@leaf> 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) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3409 Lines: 67 On Tue, Aug 14, 2012 at 08:03:41AM -0400, Josh Boyer wrote: > On Mon, Aug 13, 2012 at 9:18 PM, Josh Triplett wrote: > > On Mon, Aug 13, 2012 at 03:39:54PM -0700, Randy Dunlap wrote: > >> On 08/13/2012 03:08 PM, Thai Bui wrote: > >> >Hi all, > >> > > >> >I am as part of a capstone group at Portland State University is working > >> >to tinify the kernel as small as possible. The ultimate goal is to make > >> >the kernel small enough to use on micro-controller (or under < 200k). > >> >This patch is one of them, it saves 176 bytes on a minimal configuration > >> >of the kernel (the bzImage file was reduced from 363264 bytes to 363264 > >> >bytes applying this patch). > >> > > >> >Aside from the purpose of reducing the size of the kernel. We are also > >> >trying to clean up the kernel by making Kconfig options to compile out > >> >the stuffs that aren't used often. > >> > >> IMO the kernel already has too many kconfig options. > >> > >> Also, personally I would not merge a patch that saves so little memory, > >> especially on what I consider a very useful option. > > > > I think Thai undersold his patch significantly; the *compressed* size > > went down by 176 bytes, and the uncompressed size went down more than > > that. And that's the savings starting from a very minimal kernel, not > > starting from a defconfig kernel. > > > > In any case, do you object to the introduction of a Kconfig option at > > all, or to that option defaulting to off? In particular, would you > > object if the option only showed up if EMBEDDED, and defaulted to y? At > > that point, you could reasonably expect that most users and distros will > > have it enabled, so you'll be able to count on asking people to enable > > it and send you the output. Would that suffice? > > Hiding it behind EMBEDDED might be a start. From a distro perspective, > we actually use this particular option quite often so keeping the > ability to use it as you describe is important. Fair enough. > > The patch itself seems incredibly straightforward and non-invasive to > > me; it just stubs out the global variable and lets GCC fold away all the > > code. > > > > At this point, the kernel is running out of major things to cut out to > > save space; getting from ~200k (the current smallest kernel possible) to > > much less than that will require a pile of patches that save anywhere > > from a few hundred bytes to a few kilobytes. I certainly agree that > > those patches need to avoid introducing too much complexity. However, I > > don't think it makes sense to object to a patch that saves space solely > > on the grounds that it doesn't save *more* space. That would make it > > impossible to cut out small things, and small things add up. > > If you're really going to pursue that, I'd suggest hiding the removals > behind a new option that most people won't set. Most of the other options added via this project have used EXPERT or EMBEDDED. This one originally seemed enough like a debugging option to warrant just using DEBUG_KERNEL and let it default to N, but it sounds like this one needs to use EMBEDDED as well. - Josh Triplett -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/