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Date:      Mon, 8 Apr 2013 21:28:58 -0500
From:      Kevin Day <toasty@dragondata.com>
To:        Alfred Perlstein <bright@mu.org>
Cc:        freebsd-hackers@freebsd.org, Adrian Chadd <adrian@freebsd.org>, Amit Rawat <aamitr4@gmail.com>, Jilles Tjoelker <jilles@stack.nl>
Subject:   Re: GSOC 2013 project " Kernel Size Reduction for Embedded System "
Message-ID:  <FEDB1271-6D11-4F9A-A4DF-B2AD717DB067@dragondata.com>
In-Reply-To: <5163622F.60604@mu.org>
References:  <CAOhv3dpTM9J9oiLpdw8xOAToXT_tQ3VW4Mv1F%2B8n7xhG%2BJK93w@mail.gmail.com> <20130408224423.GA64696@stack.nl> <CAJ-VmonVre%2BVT2tTdQf3hA6DvKifqrJtxDT1RX8KEyW6a-=EXQ@mail.gmail.com> <5163622F.60604@mu.org>

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On Apr 8, 2013, at 7:34 PM, Alfred Perlstein <bright@mu.org> 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.





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