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Date:      Tue, 8 Mar 2016 14:32:33 -0700
From:      Brad Walker <bwalker@musings.com>
To:        Warner Losh <imp@bsdimp.com>
Cc:        "freebsd-embedded@freebsd.org" <freebsd-embedded@freebsd.org>
Subject:   Re: ? about kernel size..
Message-ID:  <CAPKZHbW%2BG7WnSU__yeYBVPqs8MPmFm-5q_wM4sm9FxHhEEgPDg@mail.gmail.com>
In-Reply-To: <CANCZdfriqr24Lh9ZuptaC0gEm6gAV6LN9XHcVAJtbyaBejEgNg@mail.gmail.com>
References:  <CAPKZHbVyPji-bZwDzM77TN6qybjRcf%2BZe5r6WZmbG98LkhT-rg@mail.gmail.com> <CANCZdfriqr24Lh9ZuptaC0gEm6gAV6LN9XHcVAJtbyaBejEgNg@mail.gmail.com>

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On Tue, Mar 8, 2016 at 11:42 AM, Warner Losh <imp@bsdimp.com> wrote:

>
>
> On Tue, Mar 8, 2016 at 10:42 AM, Brad Walker <bwalker@musings.com> wrote:
>
>> I'm looking at working on a new project that will use the FreeBSD kernel.
>> I
>> would attempt to embed the kernel on a very small NXP Kinetis chip. I've
>> previously done this using a Linux kernel but also had DDR memory attached
>> to the chip. This project would not have a DDR chip attached.
>>
>> So a couple of questions. 1 - What is the smallest size I could configure
>> the FreeBSD kernel out of the box? Could I get the size to be less than
>> 10MB, 5MB, 2MB, or etc.?
>>
>
> I've managed to get this down to about 2MB or a bit smaller. Compressed
> this can be a little smaller. It takes a fair amount of work, but it can be
> done.
>
>

That's great.. Was this out of the box tuning?


>
> I did a little bit of research on the PicoBSD and NanoBSD but that still
>> seem to be targeted to a little bit bigger chip than I have available.
>>
>
> How big a chip do you have? NanoBSD currently needs at least
> 64MB (and ideally 128MB) of storage. PicoBSD can be a bit smaller.
>

I have 2MB on-chip flash and 512KB of SRAM. There is an external flash that
will be attached. What I'm currently thinking is that I would like to boot
into BusyBox verses multi-user..

One question that I'm curious about. All the work that I do on this, or
you've done in the past, how does it get integrated into the mainline build.

-brad w.



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