? about kernel size..

[Brad Walker]

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

>
>
> On Tue, Mar 8, 2016 at 10:42 AM, Brad Walker <bwalker at 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.