[PATCH] scripts/Makefile.lib: also consider $(CONFIG_SYS_BOARD)-u-boot.dtsi

[Rasmus Villemoes]

On 25/04/2023 22.09, Tom Rini wrote:
> On Tue, Apr 25, 2023 at 10:02:01PM +0200, Rasmus Villemoes wrote:
>> On 25/04/2023 21.31, Tom Rini wrote:
>>> On Fri, Mar 17, 2023 at 11:26:39AM +0100, Rasmus Villemoes wrote:
>>>
>>
>>>> Now, the only way to be really sure is to build the world
>>>> with/without this patch and check if any .dtb file changes, but I
>>>> don't have the means to do that.
>>>
>>> So, yes, this causes a bunch of fail to builds, as you noted above. The
>>> easiest way I think to confirm things before / after would be to make a
>>> quick change to tools/buildman/builderthread.py and self.CopyFiles line
>>> for keep_outputs to also keep the dtb or some dts files so you can diff
>>> before / after to make sure the end result is the same.
>>
>> Do the builds outright fail, or do they fail in the sense that some
>> machinery detects a change in the binary artifacts? Can you point me at
>> one or two CI builds that show this?
> 
> They outright fail to build, mt8516_pumpkin is the one I was testing
> with.

Gah, of course.

dtb-$(CONFIG_ARCH_MEDIATEK) += \
        mt7622-rfb.dtb \
        mt7623a-unielec-u7623-02-emmc.dtb \
        mt7622-bananapi-bpi-r64.dtb \
        mt7623n-bananapi-bpi-r2.dtb \
        mt7629-rfb.dtb \
        mt7981-rfb.dtb \
        mt7981-emmc-rfb.dtb \
        mt7981-sd-rfb.dtb \
        mt7986a-rfb.dtb \
        mt7986b-rfb.dtb \
        mt7986a-sd-rfb.dtb \
        mt7986b-sd-rfb.dtb \
        mt7986a-emmc-rfb.dtb \
        mt7986b-emmc-rfb.dtb \
        mt8183-pumpkin.dtb \
        mt8512-bm1-emmc.dtb \
        mt8516-pumpkin.dtb \
        mt8518-ap1-emmc.dtb

means that we end up building a million .dtbs that are not actually
relevant to the board we're building for, and the value of
CONFIG_SYS_BOARD==mt8516 is of course completely inappropriate for
mt7622-rfb.dtb, and the nodes mentioned in mt8516-u-boot.dtsi don't
exist in mt7622...

[To add insult to injury, it seems that currently mt8516-u-boot.dtsi is
not actually being included when building mt8516-pumpkin.dtb, but it
seems that the intention very much is that it should be - except that
mt8516-u-boot.dtsi has a typo (it refers to a label topckgen_ , but the
trailing underscore shouldn't be there) - confirming that it does in
fact not get used.]

I wonder why this isn't already a problem, but I guess that in practice
we never hit the CONFIG_SYS_CPU or CONFIG_SYS_VENDOR cases.

Not sure what to do. I think it's a little counterproductive to build
all these .dtbs when they are not needed, and silly to have to add one's
.dtb to some semi-random list - which is why I pushed for 3609e1dc5f4d
to get in.

And since we very much allow the .dtbs to depend on various CONFIG_
settings - both because different .configs can cause different
-u-boot-dtsi files to get included, and also because we allow direct use
of CONFIG_* values (or in #if, #ifdef), there's no guarantee that the
mt7629-rfb.dtb built with mt8516_pumpkin_defconfig is identical to the
one built with mt7629_rfb_defconfig. So what exactly is the point of
building all those irrelevant .dtbs?

So obviously my patch cannot go in as-is. But I do think there are some
things that need to be rethought in our build system.

Now that all of CONFIG_OF_LIST gets built automatically, couldn't we
delete most if not all of the dtb-$(CONFIG_SOMETHING) += stanzas?

Or to make the build of those extra dtbs a little more deterministic and
fix the issue with a random/wrong/inapplicable -u-boot.dtsi being picked
up, perhaps change the %.dtb rule so that the the magic *-u-boot.dtsi
file (whichever one applies) is only included when $@ is in
CONFIG_$(SPL_)OF_LIST?

Rasmus