[U-Boot] [RFC PATCH 04/17] kconfig: add defconfig files for all boards

[Masahiro Yamada]

Hi Daniel,


> agree. But at first we should introduce Kconfig files in all arch,
> CPU, SOC, SOC common, board vendor, board and driver directories where
> we put all CONFIG_SYS_ symbols. We also need to convert the current
> config options for CPU, SOC, vendor and board. For example:
> 
> CONFIG_SYS_CPU="armv7"
> CONFIG_SOC_DIR=y
> CONFIG_SYS_SOC="tegra30"
> CONFIG_SYS_BOARD="beaver"
> CONFIG_VENDOR_DIR=y
> CONFIG_SYS_VENDOR="nvidia"
> CONFIG_SYS_CONFIG_NAME="beaver"
> 
> should be converted to something like this:
> 
> CONFIG_CPU_ARMV7=y
> CONFIG_SOC_TEGRA30=y
> CONFIG_VENDOR_NVIDIA=y
> CONFIG_BOARD_BEAVER=y
> 
> Then we can use the Kconfig symbol dependencies to create a minimal
> working board config. For example:
> 
> board/nvidia/beaver/Kconfig:
> config BOARD_BEAVER
>     bool "board description"
>     select VENDOR_NVIDIA
>     select SOC_TEGRA30
>     select SPL
>     ...
> 
> arch/arm/cpu/armv7/tegra30/Kconfig:
> config SOC_TEGRA30
>     bool
>     select ARMV7
>     ...
> 
> The beaver_defconfig file could reduced then to
> "CONFIG_BOARD_BEAVER=y" and some default user-editable options.


Basicly I think it's a good idea, but I am afraid there are some
problems.

[1]
First, in this case, how can we select the target board?

Like this?

choice
        prompt "Board select"
        default BOARD_SANDBOX

config BOARD_VEXPRESS_AEMV8A
        bool "vexpress_aemv8a board"

config BOARD_ARCANGEL4
        bool "arcangel4 board"

    [ Snip: a thousand of boards ]

endchoice

If we run "make config", a bunch of board choices
would be displayed and be gone away quickly.
For "make menuconfig", it would be hard to select the board
you are aiming at.


Maybe we should choose it in the top-down order?
Like this?

(1) 1st Level : Architecture select

choice
        prompt "Architecture select"

config ARM
        bool "ARM architecture"

   .....

(2) 2rd Level: CPU select
choice
        prompt "CPU select"
        depends on ARM

config CPU_ARMV7
        bool "ARM v7"
 
     ....

(3) 3rd level: SoC select

choice
        prompt "SoC select"
        depends on CPU_ARMV7

config SOC_TEGRA
        bool "Tegra SoC"

   .....

(4) 4th level: Board select

choice
        prompt "Board select"
        depends on SOC_TEGRA

config BOARD_BEAVER
        bool "Tegra SoC"


[2]
CONFIG_CPU_
CONFIG_SOC_
CONFIG_VENDOR_
CONFIG_BOARD_
are systematic prefixes and easy to understand.

But there are already some macros bound to
specific CPUs, SoCs.

For example,
CONFIG_SOC_TEGRA30 would be the same as
existing CONFIG_TEGRA30.

We will have to merge macros with the same meaning.

[3]
How to select board directoy by using boolean macros.

If we try to emulate arch/arm/Makefile of Linux,

board-$(CONFIG_BOARD_VEXPRESS_AEMV8A)   := vexpress_aemv8a
board-$(CONFIG_BOARD_AXS101)                     := axs101
board-$(CONFIG_BOARD_ARCANGEL4)               := arcangel4

Like this?



Best Regards
Masahiro Yamada