Barebone kernel options request

Matthias Oestreicher matthias at
Sun Mar 10 22:21:52 UTC 2019

Am Sonntag, den 10.03.2019, 13:58 +0100 schrieb
samir.otmane at
> Hello everyone,
> For my purpose, i would like to get a very barebone FreeBSD kernel (
> For instance i don't want jaling, i'll want to get rid of unwanted
> overhead ), but i don't know how to do so.
> IRC chatters told me that it would be very challenging to do so.
> I found that page ( 
> ) but it only
> disables user-land program building, not kernel-land code.
> I'm looking towards an answer for it
> thank you in advance
> Samir
Hei Samir,

I guess what you want is this

In /usr/src/sys/<ARCH>/conf/MINIMAL you already have a very stripped
down kernel configuration file. I haven't build this myself though.
The kernel FreeBSD runs on by default is, what you would end up if you
build the GENERIC kernel.

Really, nowadays you must to be extremely low on recources to feel a
differnce between GENERIC or something you stripped down.

But if you want to try it, go on. If you got a bit of knowledge about
hardware drivers, buses etc it will definetely help.

Basically, edit GENERIC, strip out the masses of raid controller and
network interfaces that you don't need and build it.
That's a good start to learn.
Read the comments on each line! Don't touch anything that has "bus" in
it's device name or comment if your are unexperienced, e.g. scbus or
miibus. The latter is listed with the network interface drivers, but
it's a bus that many cheap network interfaces depend on. You may savely
remove parallel port bus though 😉 

In the end, you should clearly know what FreeBSD needs to run and what
you need/want. That depends heavily on the hard- and software setup you
are going to run.

There is also a ../../conf/NOTES as mentioned in the header of GENERIC
that has very exaustive comments. Though I find them more useful if you
want a add something. The most important comments are in the GENERIC
config file.

Best Regards,
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Med vennlig hilsen

Matthias Oestreicher
Industri- og produksjonsservice Oestreicher
Solsletta 34
4658 Tveit
t: (+47) 41 18 44 18
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