From owner-freebsd-hackers@FreeBSD.ORG Tue Apr 9 02:29:03 2013 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by hub.freebsd.org (Postfix) with ESMTP id F25D6CD3 for ; Tue, 9 Apr 2013 02:29:03 +0000 (UTC) (envelope-from toasty@dragondata.com) Received: from mail-ie0-x22b.google.com (mail-ie0-x22b.google.com [IPv6:2607:f8b0:4001:c03::22b]) by mx1.freebsd.org (Postfix) with ESMTP id C0802A5B for ; Tue, 9 Apr 2013 02:29:03 +0000 (UTC) Received: by mail-ie0-f171.google.com with SMTP id e14so7926281iej.2 for ; Mon, 08 Apr 2013 19:29:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=dragondata.com; s=google; h=x-received:content-type:mime-version:subject:from:in-reply-to:date :cc:content-transfer-encoding:message-id:references:to:x-mailer; bh=/dpaBv+Z7rR62XR/uaP3gj26Su6/Xxj+OhO/kehA3ho=; b=CJnxkK+Uf9xlhKF8UBWJqvqfxd7A8UQb/NfgH0/uV/ZDaHklBDiX+3JkhZcEmStX+W Dfbz/dnVeVmF0+MFXgRMTRqZUGm60naDnjvR6nn72eaw4kNGNWx7fvBXJPucwOxS3O3U s3gmCVL2ZL3W96o0q6gbPhadEpyfRpVD1n3hE= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=x-received:content-type:mime-version:subject:from:in-reply-to:date :cc:content-transfer-encoding:message-id:references:to:x-mailer :x-gm-message-state; bh=/dpaBv+Z7rR62XR/uaP3gj26Su6/Xxj+OhO/kehA3ho=; b=E5v/ufpbfjBjO80vcscwhTr6fxO5Ev5P1VjfjoQ8wkuwtLl87jYATXIqlXobjKkAlK zWiof25hCasYnkfXiplJyhf7icwUtspjGWqUeTA4fA6/lMAm/iGOt+CRNHweJgNmjz3y h2NSJ9dW1ToTqNSBGI5BvZfOApUSGne+H8Q4oWNHqQGgV0wnqzCE28l25F4YgcS8NrYr tDWrX1gWbqsynh9xOosvg9xAF1w6WTvBpaw8BE3zh3AfosINTw5sSEgh5XhEIQyQcsMW 6XYNUE667J4JpFhCeXyhcts0Nt0pjQWA8ElX6hg1mcH62hiUD37z46YIeD+xrvp395Nl tQiQ== X-Received: by 10.50.135.105 with SMTP id pr9mr9184327igb.6.1365474542347; Mon, 08 Apr 2013 19:29:02 -0700 (PDT) Received: from vpn132.rw1.your.org (vpn132.rw1.your.org. [204.9.51.132]) by mx.google.com with ESMTPS id ih1sm20897127igc.3.2013.04.08.19.29.00 (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Mon, 08 Apr 2013 19:29:01 -0700 (PDT) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 6.3 \(1503\)) Subject: Re: GSOC 2013 project " Kernel Size Reduction for Embedded System " From: Kevin Day In-Reply-To: <5163622F.60604@mu.org> Date: Mon, 8 Apr 2013 21:28:58 -0500 Content-Transfer-Encoding: quoted-printable Message-Id: References: <20130408224423.GA64696@stack.nl> <5163622F.60604@mu.org> To: Alfred Perlstein X-Mailer: Apple Mail (2.1503) X-Gm-Message-State: ALoCoQlZFOd2QDNsmzZHHQrB+RVKIJKQ6RyhZ2+tIjdGS5UmxlmcE34GxcRDsGvQlqgiKJ+8HiNK Cc: freebsd-hackers@freebsd.org, Adrian Chadd , Amit Rawat , Jilles Tjoelker X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 09 Apr 2013 02:29:04 -0000 On Apr 8, 2013, at 7:34 PM, Alfred Perlstein wrote: > However, until a bunch of embedded folks come forward and state what = they are really willing to sacrifice, then we won't really have anything = to go on, and it will be guessing at what will work for a space that not = all of us are familiar with. >=20 > So I'm hoping some people can make the tough call to give direction = here, otherwise nothing good will come of it. >=20 > Has anyone actually done this? Or maybe compared against another = embedded OS? Ages ago we had to make things work in 16 or 32MB of total system memory = on i386.=20 For the most part, disabling every compiled-in option/driver we didn't = need was 90% of the effort. Which options/drivers is going to be totally = application dependent, so that really can't be done for you. As for the rest, there isn't any large low hanging fruit that can get = culled from the kernel easily. The base kernel isn't modular enough to = trim out individual syscalls or anything, and doing so wouldn't have = made a huge dent. There are a lot of ways FreeBSD could be more embedded friendly (being = able turn on/off parts of userland depending on licenses is a huge one), = but producing a trimmed kernel isn't something I'd rank very highly. If = building a kernel with everything modularized as possible isn't small = enough, FreeBSD probably isn't going to work for you for other reasons.