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

Rasmus Villemoes rasmus.villemoes at prevas.dk
Wed May 3 10:25:21 CEST 2023

On 01/05/2023 18.32, Simon Glass wrote:
> Hi Rasmus,
> On Mon, 1 May 2023 at 02:49, Rasmus Villemoes
> <rasmus.villemoes at prevas.dk> wrote:
>> On 27/04/2023 19.31, Tom Rini wrote:
>>>> Well, I'm not sure there's a use case for building all of the extra
>>>> device trees. I think what I'll do right now is fire off a CI run (or a
>>>> few, in the event of problems) where we just use the logic of
>>>> 3609e1dc5f4d and see what falls down.
>>> So this gets us a few failures.  You can see them on
>>> https://source.denx.de/u-boot/u-boot/-/jobs/618127 but one type of
>>> failure seems to be the case where CONFIG_DEFAULT_DEVICE_TREE isn't
>>> contained in CONFIG_OF_LIST (ls1088aqds_tfa for example) and the other
>>> case is where CONFIG_OF_LIST != CONFIG_SPL_OF_LIST and this fails
>>> because fdtgrep runs NOT on spl/arch/.../foo.dtb but rather
>>> arch/.../foo.dtb and so we don't have the dtb file around.
>> Hm, the former sounds like a bug in the defconfig, the second sounds
>> like a legit use case (or why would we have SPL_OF_LIST). Anyway, both
>> should be fixable by just changing the logic of scripts/Makefile.dts a
>> little; say add the union of DEFAULT_DEVICE_TREE, OF_LIST and
>> SPL_OF_LIST to dtb-y. Something like
>> diff --git a/scripts/Makefile.dts b/scripts/Makefile.dts
>> index 2561025da8..5e2429c617 100644
>> --- a/scripts/Makefile.dts
>> +++ b/scripts/Makefile.dts
>> @@ -1,3 +1,3 @@
>>  # SPDX-License-Identifier: GPL-2.0+
>> -dtb-y += $(patsubst %,%.dtb,$(subst ",,$(CONFIG_$(SPL_)OF_LIST)))
>> +dtb-y += $(patsubst %,%.dtb,$(subst ",,$(CONFIG_DEFAULT_DEVICE_TREE)
> I think we should require that all the DTs in the list are already
> built using the standard rule.
> i.e. Makefile.dts should just have a check that OF_LIST doesn't bring
> in anything new. If it does, then the build should fail.

I disagree.

IMO, having those enourmous lists is unmaintainable, and
as I've pointed out, actively misleading because (like it or not), the
result of building foo.dtb depends (or to be pedantically correct, _may
depend_) on whether we're building foo_defconfig or bar_defconfig,
despite both foo and bar being members of the same SOC family or vendor
or however foo.dtb and bar.dtb have been categorized.

> The list is really about which ones should be put into the FIT. We
> shouldn't be putting in things that don't exist normally for that SoC.

Yes, and I'm not talking about changing any of _that_. I'm just saying:
The board, in the form of the defconfig, already provides information on
which dtbs can be relevant for any bootphase, so let's just build the
union of those, _but nothing else_.

> Meanwhile I think we should move towards prohibiting CONFIG_TARGET_...
> in Makefile rules,

I think we can get rid of all of it, or perhaps with some exceptions for
sandbox and the like. I mean, Tom's quick test didn't show that many
problems from just nuking almost all of arch/*/dts/Makefile.

 since this is creating some of this problem. i.e.
> we should do what Linux does.

I don't think so. Linux (and in general an OS kernel) is in a completely
different situation than a bootloader. It's possible to build one kernel
that will boot on many different boards with just an appropriate dtb
being passed. A bootloader will always need to be built for the specific
target (or for a very close family of targets); you can't really imagine
building an imx_defconfig u-boot binary and expect that to run on all

That said, there's another thing "Linux does", at least right now for
arm64 and soonish also for arm32, namely putting dts files in individual
vendor directories. _That_ I'd really love to see happen in U-Boot as
well, because it's not just the 1400 line Makefile that's unmaintanable,
it's also the 2600+ files in one directory.


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