boards: set CONFIG_BOARD default based on devicetree

[galak]

No description provided.

[mbolivar-nordic]

This is cool, but makes some problems we have worse.

@tejlmand and I have been talking about how it's a problem that CONFIG_BOARD in Kconfig doesn't have to match BOARD in CMake. You see this most often in Arm v8-M boards with trustzone, where BOARD=foo_ns and BOARD=foo both have CONFIG_BOARD=foo. That's a bug in our opinion; consistency between BOARD and CONFIG_BOARD should be enforced. This PR would make that harder to do.

[tejlmand]

Agree with @mbolivar-nordic.

The principle is cool, but makes inconsistency worse.
Another issue that will arise is the sysbuild intregration.

Already now it's hard impossible to reuse the Kconfig tree for boards and SoC, but ideally we would like to be able to source part of the tree into sysbuild.
Namely the generic parts containing names but potentially other things, this is not fully decided.
Reason for this, is one may be like to have images available based on board / SoC / hw.

For example enabling a netcore image, such as HCI RPMsg, when building on a nRF5340, but not other boards.
Same could be true for features like Trustzone.

See also: #43488

And sysbuild is not (yet) using devicetree, so sourcing information from there makes things more complex.
Though system devicetree may change the situation quite significantly in future.

[galak]

This is cool, but makes some problems we have worse.

@tejlmand and I have been talking about how it's a problem that CONFIG_BOARD in Kconfig doesn't have to match BOARD in CMake. You see this most often in Arm v8-M boards with trustzone, where BOARD=foo_ns and BOARD=foo both have CONFIG_BOARD=foo. That's a bug in our opinion; consistency between BOARD and CONFIG_BOARD should be enforced. This PR would make that harder to do.

@mbolivar-nordic @tejlmand so why don't we effectively add -DCONFIG_BOARD= to set this to match and remove the Kconfig.defconfig setting of CONFIG_BOARD?

[erwango]

s/number/name

[mbolivar-nordic]

why don't we effectively add -DCONFIG_BOARD= to set this to match and remove the Kconfig.defconfig setting of CONFIG_BOARD?

I don't get what you mean, sorry.

[galak]

I don't get what you mean, sorry.

I mean if CONFIG_BOARD is suppose to match the cmake -DBOARD, why don't we enforce/pass that through from Cmake to Kconfig. Instead of having CONFIG_BOARD set in Kconfig files?

[tejlmand]

I don't get what you mean, sorry.

I mean if CONFIG_BOARD is suppose to match the cmake -DBOARD, why don't we enforce/pass that through from Cmake to Kconfig. Instead of having CONFIG_BOARD set in Kconfig files?

work has been taken up by @nordicjm on this, if curious, see this commit for details: ab05d91

[mbolivar-nordic]

see this commit for details: ab05d91

This commit isn't helpful; do you have a branch pointer?

[galak]

This commit isn't helpful; do you have a branch pointer?

I assume #50154 is related to what @tejlmand mentioned.

[tejlmand]

This commit isn't helpful; do you have a branch pointer?

@mbolivar-nordic github is playing tricks here. 👿
Cause the link takes you directly to a commit, without PR information, but if you look at the real link in the message (click edit on that message), then this is the link it contains:

https://github.com/zephyrproject-rtos/zephyr/pull/50154/commits/ab05d915496d40f0007a9f95f7aa15960ba2bb9a

which includes the PR number 50154, which is why I posted the link like that.
The interesting PR is part of the commit link, so everyone should be able to locate both pieces of information 😄