[U-Boot] [PATCH] tools/Makefile: fix HOSTCFLAGS with CROSS_BUILD_TOOLS

[Jan Kiszka]

On 25.08.19 21:11, Fabrice Fontaine wrote:
> Le dim. 25 août 2019 à 17:49, Jan Kiszka <jan.kiszka at web.de> a écrit :
>>
>> On 25.08.19 17:13, Fabrice Fontaine wrote:
>>> Le dim. 25 août 2019 à 16:11, Jan Kiszka <jan.kiszka at web.de> a écrit :
>>>>
>>>> On 25.08.19 15:43, Fabrice Fontaine wrote:
>>>>> Hello,
>>>>> Le dim. 25 août 2019 à 13:44, Jan Kiszka <jan.kiszka at web.de> a écrit :
>>>>>>
>>>>>> On 01.05.19 15:08, Fabrice Fontaine wrote:
>>>>>>> When CROSS_BUILD_TOOLS is set, set HOSTCFLAGS to CFLAGS otherwise CC
>>>>>>> will be used with HOSTCFLAGS which seems wrong
>>>>>>>
>>>>>>> Signed-off-by: Fabrice Fontaine <fontaine.fabrice at gmail.com>
>>>>>>> ---
>>>>>>>      tools/Makefile | 1 +
>>>>>>>      1 file changed, 1 insertion(+)
>>>>>>>
>>>>>>> diff --git a/tools/Makefile b/tools/Makefile
>>>>>>> index 12a3027e23..eadeba417d 100644
>>>>>>> --- a/tools/Makefile
>>>>>>> +++ b/tools/Makefile
>>>>>>> @@ -272,6 +272,7 @@ subdir- += env
>>>>>>>
>>>>>>>      ifneq ($(CROSS_BUILD_TOOLS),)
>>>>>>>      override HOSTCC = $(CC)
>>>>>>> +override HOSTCFLAGS = $(CFLAGS)
>>>>>>>
>>>>>>>      quiet_cmd_crosstools_strip = STRIP   $^
>>>>>>>            cmd_crosstools_strip = $(STRIP) $^; touch $@
>>>>>>>
>>>>>>
>>>>>> This eats - among other things - -O2, normally set in /Makefile. And that breaks
>>>>>> CROSS_BUILD_TOOLS=y with CONFIG_FIT but without CONFIG_FIT_SIGNATURE because "if
>>>>>> (!IMAGE_ENABLE_SIGN)" is no longer optimized. I tend to believe this should
>>>>>> simply be reverted (which is what I'm doing locally in order to fix my builds).
>>>>> I don't think this patch should be reverted, I sent it to fix a
>>>>> cross-compilation build issue with host-openssl.
>>>>>
>>>>> Indeed, without this patch, with CROSS_BUILD_TOOLS=y, tools/Makefile
>>>>> sets HOSTCC=$(CC) but it forgets
>>>>> to override HOSTCFLAGS, though, so the tools are built with target
>>>>> compiler but host CFLAGS.
>>>>>
>>>>> This raises a build failure if host-openssl is built before uboot-tools because
>>>>> uboot-tools links with openssl headers from host which depends on pthread.h
>>>>>
>>>>> More information can be found on buildroot's patchwork here:
>>>>> - https://patchwork.ozlabs.org/patch/1092227
>>>>> - https://patchwork.ozlabs.org/patch/1093385
>>>>>>
>>>>>> Jan
>>>>>
>>>>> Best Regards,
>>>>>
>>>>> Fabrice
>>>>>
>>>>
>>>> So what is your suggestion to fix the O2-regression best?
>>> I'm far from being an expert in uboot so please excuse me if my answer
>>> contains some mistakes.
>>> However, IMHO, we should not pass -O2 or any other optimization flags.
>>>   From my understanding, CFLAGS (and so HOSTCFLAGS when building tools
>>> for the target through cross-tools) will (or should?) contain -O2 or
>>> -Os depending on CONFIG_CC_OPTIMIZE_FOR_SIZE value.
>>> However, I do understand that this is a change in the former behavior
>>> that was always passing -O2 in HOSTCFLAGS.
>>> So, if you really want to pass -O2, I would add it to HOSTCFLAGS in
>>> tools/Makefile (after the override).
>>
>> This is a hack. U-boot relies on >= -O2 for proper build, so it must inject this
>> setting on its own - which it did prior to your change. I think top-level
>> HOSTCFLAGS belongs to the build, irrespective of native vs. cross. You may allow
>> appending (and, thus, overwriting) settings but you cannot remove mandatory ones.
>>
>>> However, I have to confess that I don't understand why the build
>>> breaks "if (!IMAGE_ENABLE_SIGN)" is no longer optimized."
>>
>> IMAGE_ENABLE_SIGN is 0 when CONFIG_FIT_SIGNATURE is not set. That will remove
>> all code from tools/image-host.c which is not reachable then. When it's not
>> removed because of default optimization settings, we get linker errors because
>> common/image.sig.c is not built without CONFIG_FIT_SIGNATURE. I assume this way
>> was preferred over #ifdef'ery, but it's broken now.
> Thanks a lot for your explanation.
> I was able to reproduce the issue and I think that
> https://github.com/ffontaine/u-boot/commit/61a162e5c0343fc55304902042f8c9adfe531f51
> should fixed it.
> Can you review it? I can also directly send a PR.

I still think that dropping the content of HOSTCFLAGS is the actual bug. There
is more than -O2 that you lose. If you want your CFLAGS to be respected, append
them.

Jan