Re: [PATCH] kbuild: take into account DT_SCHEMA_FILES changes while checking dtbs

[Dmitry Baryshkov <dmitry.baryshkov@linaro.org>]

On 16/09/2022 17:54, Rob Herring wrote:
> On Fri, Sep 16, 2022 at 9:21 AM Dmitry Baryshkov
> <dmitry.baryshkov@linaro.org> wrote:
>>
>> On Fri, 16 Sept 2022 at 04:10, Masahiro Yamada <masahiroy@kernel.org> wrote:
>>>
>>> On Thu, Sep 15, 2022 at 8:40 PM Dmitry Baryshkov
>>> <dmitry.baryshkov@linaro.org> wrote:
>>>>
>>>> On Thu, 15 Sept 2022 at 07:51, Masahiro Yamada <masahiroy@kernel.org> wrote:
>>>>>
>>>>> On Sun, Sep 11, 2022 at 2:36 AM Dmitry Baryshkov
>>>>>
>>>>> <dmitry.baryshkov@linaro.org> wrote:
>>>>>>
>>>>>> On Thu, 4 Aug 2022 at 18:27, Rob Herring <robh+dt@kernel.org> wrote:
>>>>>>>
>>>>>>> On Fri, Jul 29, 2022 at 1:46 AM Dmitry Baryshkov
>>>>>>> <dmitry.baryshkov@linaro.org> wrote:
>>>>>>>>
>>>>>>>> On Fri, 29 Jul 2022 at 10:05, Masahiro Yamada <masahiroy@kernel.org> wrote:
>>>>>>>>>
>>>>>>>>> On Fri, Jul 29, 2022 at 3:53 PM Dmitry Baryshkov
>>>>>>>>> <dmitry.baryshkov@linaro.org> wrote:
>>>>>>>>>>
>>>>>>>>>> On Fri, 29 Jul 2022 at 08:55, Masahiro Yamada <masahiroy@kernel.org> wrote:
>>>>>>>>>>>
>>>>>>>>>>> On Thu, Jul 28, 2022 at 2:36 AM Rob Herring <robh+dt@kernel.org> wrote:
>>>>>>>>>>>>
>>>>>>>>>>>> On Wed, Jul 27, 2022 at 4:06 AM Dmitry Baryshkov
>>>>>>>>>>>> <dmitry.baryshkov@linaro.org> wrote:
>>>>>>>>>>>>>
>>>>>>>>>>>>> It is useful to be able to recheck dtbs files against a limited set of
>>>>>>>>>>>>> DT schema files. This can be accomplished by using differnt
>>>>>>>>>>>>> DT_SCHEMA_FILES argument values while rerunning make dtbs_check. However
>>>>>>>>>>>>> for some reason if_changed_rule doesn't pick up the rule_dtc changes
>>>>>>>>>>>>> (and doesn't retrigger the build).
>>>>>>>>>>>>>
>>>>>>>>>>>>> Fix this by changing if_changed_rule to if_changed_dep and squashing DTC
>>>>>>>>>>>>> and dt-validate into a single new command. Then if_changed_dep triggers
>>>>>>>>>>>>> on DT_SCHEMA_FILES changes and reruns the build/check.
>>>>>>>>>>>>>
>>>>>>>>>>>>> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
>>>>>>>>>>>>> ---
>>>>>>>>>>>>>   scripts/Makefile.lib | 14 ++++++--------
>>>>>>>>>>>>>   1 file changed, 6 insertions(+), 8 deletions(-)
>>>>>>>>>>>>>
>>>>>>>>>>>>> diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
>>>>>>>>>>>>> index c88b98b5dc44..3df470289382 100644
>>>>>>>>>>>>> --- a/scripts/Makefile.lib
>>>>>>>>>>>>> +++ b/scripts/Makefile.lib
>>>>>>>>>>>>> @@ -383,17 +383,15 @@ DT_CHECKER_FLAGS ?= $(if $(DT_SCHEMA_FILES),-l $(DT_SCHEMA_FILES),-m)
>>>>>>>>>>>>>   DT_BINDING_DIR := Documentation/devicetree/bindings
>>>>>>>>>>>>>   DT_TMP_SCHEMA := $(objtree)/$(DT_BINDING_DIR)/processed-schema.json
>>>>>>>>>>>>>
>>>>>>>>>>>>> -quiet_cmd_dtb_check =  CHECK   $@
>>>>>>>>>>>>> -      cmd_dtb_check =  $(DT_CHECKER) $(DT_CHECKER_FLAGS) -u $(srctree)/$(DT_BINDING_DIR) -p $(DT_TMP_SCHEMA) $@ || true
>>>>>>>>>>>>> +quiet_cmd_dtb =        DTC/CHECK   $@
>>>>>>>>>>>>
>>>>>>>>>>>> This is supposed to be 7 chars or less. DTCCHK or DTC_CHK perhaps. Or
>>>>>>>>>>>> always do just 'DTC'. I can fixup when applying.
>>>>>>>>>>>>
>>>>>>>>>>>> I'll give it a few days for other comments.
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> When you change DT_SCHEMA_FILES, re-running dt-validate should be enough.
>>>>>>>>>>> You do not need to re-run dtc.
>>>>>>>>>>>
>>>>>>>>>>> I guess the strangeness comes from the fact that you are trying to do the
>>>>>>>>>>>   two different things in a single rule.
>>>>>>>>>>
>>>>>>>>>> The issue is that with the current rules the dt-validate isn't
>>>>>>>>>> re-executed on DT_SCHEMA_FILES changes. Thus comes my proposal.
>>>>>>>>>
>>>>>>>>> Correct.
>>>>>>>>>
>>>>>>>>> What I said is like this.
>>>>>>>>>
>>>>>>>>> # touch the timestamp file, %.dtb.checked
>>>>>>>>> $(obj)/%.dtb.checked: $(obj)/%.dtb $(DT_TMP_SCHEMA) FORCE
>>>>>>>
>>>>>>> Not really a fan of the thousands of files that creates. Maybe if it
>>>>>>> was turned into something useful like a list of schemas that apply to
>>>>>>> the dtb. IOW, a dependency list. That would speed up re-running after
>>>>>>> a schema change. Though if a schema change created new dependencies,
>>>>>>> that wouldn't work.
>>>>>>>
>>>>>>>>>          $(call if_changed_rule,dtb_check)
>>>>>>>>>
>>>>>>>>> $(obj)/%.dtb: $(src)/%.dts $(DTC) $FORCE
>>>>>>>>>          $(call if_changed_rule,dtc)
>>>>>>>>>
>>>>>>>>> $(obj)/%.dtbo: $(src)/%.dts $(DTC) FORCE
>>>>>>>>>          $(call if_changed_dep,dtc)
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> With the dtc/check split, we can avoid unneeded regeneration of
>>>>>>>>> %.dtb when DT_TMP_SCHEMA or DT_SCHEMA_FILES is
>>>>>>>>> changed.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> One drawback is we track %.dtb.checked and and %.dtb separately,
>>>>>>>>> so something like 53182e81f47d4ea0c727c49ad23cb782173ab849
>>>>>>>>> may come back.
>>>>>>>>
>>>>>>>> It's up to you and Rob, but I'd really prefer a simpler solution here.
>>>>>>>> Regenerating dtbs sounds like a minor pain compared to hacking the
>>>>>>>> top-level Makefile again. What I really like is that if one has
>>>>>>>> CHECK_DTBS=y (for whatever reason), he can not generate dtb without
>>>>>>>> validation.
>>>>>>>
>>>>>>> I lean towards just rebuilding the dtbs. That's pretty quick and
>>>>>>> ensures we get dtc warnings with schema warnings. In the long run, I
>>>>>>> would like to make the schema checks not optional to run. The
>>>>>>> impediment to doing that is lots of warnings (but not not some
>>>>>>> platforms), adding a tool dependency, and validation time.
>>>>>>
>>>>>> Rob, Masahiro, do we have any conclusion here? I can change my patch,
>>>>>> but I'd like to understand in which way I should change it.
>>>>>> Fixing/testing yaml changes is a bit painful w/o this change.
>>>>>>
>>>>>> --
>>>>>> With best wishes
>>>>>> Dmitry
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> I am fine with the patch as long as you fix DTC/CHECK to DTC.
>>>>
>>>> Ack, I completely forgot about this part. Please excuse me. I'll
>>>> change it to DTC_CHK (as suggested before) to fit into 7 chars in v2.
>>>>
>>>>>
>>>>> Another idea is to re-check the schema every time,
>>>>> like this:
>>>>
>>>> I think this will add the external build dependency. We tried a
>>>> similar approach several releases ago and had to revert the change.
>>>
>>>
>>> If you are talking about
>>> 75e895343d5a2fcbdf4cb3d31ab7492bd65925f0,
>>> you are completely misunderstanding.
>>>
>>> Look at my code closely.
>>> It is how the sparse checker works with C=2.
>>
>> Ah, I see. Then I'm fine with either your patch or mine v2 at your
>> (and Rob's) preference.
> 
> I'd rather not recheck every time. The user can remove the dtbs if
> they want to do that.

Then [1] should be the better fit.

[1] 
https://lore.kernel.org/linux-kernel/20220915114422.79378-1-dmitry.baryshkov@linaro.org/

-- 
With best wishes
Dmitry