Re: [Buildroot] [PATCH v9 1/2] configs/imx8mn_bsh_smm_s2_defconfig: new defconfig

[Thomas Petazzoni via buildroot <buildroot@buildroot.org>]

Hello Dario,

On Mon, 16 Jan 2023 22:55:15 +0100
Dario Binacchi <dario.binacchi@amarulasolutions.com> wrote:

> BSH SMM S2 (SystemMaster S2) Board is an add-on board which provide
> input and output interfaces to a dedicated carrier board. It is designed
> mainly to provide graphical/video and connectivity interfaces to the
> appliance.
> 
> Board support package includes the following components:
> - mainline Linux kernel 6.1.6
> - mainline U-Boot 2022-07
> - default packages from buildroot
> 
> https://www.apertis.org/reference_hardware/imx8mn_bsh_smm_s2pro_setup/
> The smm s2 board is basically the same as the pro except it boots from
> NAND instead of eMMC.
> 
> Co-authored-by: Michael Trimarchi <michael@amarulasolutions.com>
> Signed-off-by: Michael Trimarchi <michael@amarulasolutions.com>
> Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
> Reviewed-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
> ---
> Changes in v9:
> - Bump Linux kernel to version 6.1.6.
> - Remove the Linux kernel patches because they have been merged into
>   the used version.

Thanks, I've applied both patches. One interesting point to note is
about the kernel configuration. Your Buildroot defconfig says to use
the default ARM64 kernel configuration + apply a pretty huge fragment
to disable lots of things:

 board/bsh/imx8mn-bsh-smm-s2/linux.fragment    | 895 ++++++++++++++++++

So you have a 895 lines fragment to disable lots of stuff. I was
curious to see if this fragment was not *larger* than the actual
resulting kernel configuration, as a defconfig, and indeed it is:

$ wc -l output/build/linux-6.1.6/defconfig 
816 output/build/linux-6.1.6/defconfig

And still reading this defconfig, it is pretty clear that lots of
options that are enabled are not relevant to your system, and could be
disabled, making the defconfig even smaller.

So overall, it looks like having a complete defconfig of your kernel
configuration would be smaller than a fragment that disables zillions
of things.

Best regards,

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
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