[PATCH 2/2] ARM: don't assume 32-bit when no boards are selected

[Ahmad Fatoum]

Hello Lior,

On 08.06.23 10:20, Lior Weintraub wrote:
> Hi Ahmad,
> 
> Thanks for this fix!
> Few comments:
> 1. I was getting errors when I tried to apply your patch on either "master" or "next" branch but then realized your fix was already merged to "next" :-).

Ye, Sascha was fast :-)

> 2. Indeed this fix doesn't show the original error we saw but now it shows: "error: #error No boards/CPUs selected in Kconfig". It still doesn't help to find the culprit.

How would you rephrase it to be more useful? Replace `Kconfig' with `.config'?

> 3. During the investigation, I also found another issue which is related to temp\generated build files.
> 
> The following patch introduces a mistake in Kconfig file.

What defconfig do you source after applying the patch and
what commands do you run?

> 
> diff --git a/arch/arm/mach-stm32mp/Kconfig b/arch/arm/mach-stm32mp/Kconfig
> index bc0a48d64c..97b61810d7 100644
> --- a/arch/arm/mach-stm32mp/Kconfig
> +++ b/arch/arm/mach-stm32mp/Kconfig
> @@ -30,6 +30,7 @@ config MACH_LXA_MC1
>  	bool "Linux Automation MC-1 board"
>  
>  config MACH_SEEED_ODYSSEY
> +	depends on HAVE_ARCH_STM32MP157
>  	select ARCH_STM32MP157
>  	bool "Seeed Studio Odyssey"
> 
> Now run make stm32mp_defconfig and see:
> 
> WARNING: unmet direct dependencies detected for USB_DWC2
>   Depends on [n]: USB_HOST [=y] && USB [=y] && HAS_DMA [=n]
>   Selected by [y]:
>   - USB_DWC2_HOST [=y] && USB_HOST [=y]
>   - USB_DWC2_GADGET [=y] && USB_HOST [=y] && USB_GADGET [=y]
> 
> WARNING: unmet direct dependencies detected for USB_DWC2
>   Depends on [n]: USB_HOST [=y] && USB [=y] && HAS_DMA [=n]
>   Selected by [y]:
>   - USB_DWC2_HOST [=y] && USB_HOST [=y]
>   - USB_DWC2_GADGET [=y] && USB_HOST [=y] && USB_GADGET [=y]
> 
> (Not very helpful warnings but then again I have no experience with Kbuild)
> 
> Then make -j will produce the error "#error No boards/CPUs selected in Kconfig". 
> Now even if you revert the change on Kconfig there is no way to fix the build (tried make clean) without getting a new clone into a fresh folder.

make clean intentionally doesn't wipe the configuration, only the build artifacts.

> I assume there is something left from previous build that is not cleaned correctly.

If you want to source a defconfig, use

  make my_platforms_defconfig

If you want to delete everything, use

  make mrproper

Same applies to other Kbuild projects.

> 
> Cheers,
> Lior.
> 
> 
>> -----Original Message-----
>> From: Ahmad Fatoum <a.fatoum at pengutronix.de>
>> Sent: Wednesday, June 7, 2023 6:32 PM
>> To: barebox at lists.infradead.org
>> Cc: Lior Weintraub <liorw at pliops.com>; Ulrich Ölmann
>> <u.oelmann at pengutronix.de>; Ahmad Fatoum <a.fatoum at pengutronix.de>
>> Subject: [PATCH 2/2] ARM: don't assume 32-bit when no boards are selected
>>
>> CAUTION: External Sender
>>
>> barebox build errors are very confusing if no board is selected.
>> This should have been fixed with commit 14b296d2a7e6 ("arm: error
>> out if __LINUX_ARM_ARCH__ is undefined"), but unfortunately that's
>> only true for ARM32. On ARM64, the error message in question
>> is not printed, because build aborts even earlier, because Kbuild
>> assumes it should build for 32-bit ARM and thus passes the ARM64
>> compiler options that it can't understand:
>>
>>   aarch64-oe-linux-gcc: error: unrecognized argument in option '-mabi=apcs-
>> gnu'
>>   aarch64-oe-linux-gcc: note: valid arguments to '-mabi=' are: ilp32 lp64
>>   aarch64-oe-linux-gcc: error: unrecognized command-line option '-msoft-
>> float'
>>   aarch64-oe-linux-gcc: error: unrecognized command-line option '-mno-
>> unaligned-access'
>>
>> Let's fix that for ARM64 builds by not assuming !CONFIG_CPU_64 to be 32-
>> bit,
>> but instead explicitly check that CONFIG_CPU_32 is set before doing
>> 32-bit specific changes.
>>
>> This ensures we now fail during compilation on both ARM32 and ARM64 if
>> no boards were selected. We can't fail earlier via $(error ...) as this
>> would impact use of targets like menuconfig.
>>
>> Reported-by: Lior Weintraub <liorw at pliops.com>
>> Reported-by: Ulrich Ölmann <u.oelmann at pengutronix.de>
>> Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
>> ---
>>  arch/arm/Makefile | 35 ++++++++++++++---------------------
>>  1 file changed, 14 insertions(+), 21 deletions(-)
>>
>> diff --git a/arch/arm/Makefile b/arch/arm/Makefile
>> index 926af7387f7f..337b7e9095fa 100644
>> --- a/arch/arm/Makefile
>> +++ b/arch/arm/Makefile
>> @@ -6,7 +6,8 @@ KBUILD_CPPFLAGS += -D__ARM__ -fno-strict-aliasing
>>  # Explicitly specifiy 32-bit ARM ISA since toolchain default can be -mthumb:
>>  ifeq ($(CONFIG_CPU_64),y)
>>  KBUILD_CPPFLAGS        +=$(call cc-option,-maarch64,)
>> -else
>> +endif
>> +ifeq ($(CONFIG_CPU_32),y)
>>  KBUILD_CPPFLAGS        +=$(call cc-option,-marm,)
>>  KBUILD_CPPFLAGS        += -msoft-float
>>  endif
>> @@ -27,14 +28,12 @@ endif
>>  # at least some of the code would be executed with MMU off, lets be
>>  # conservative and instruct the compiler not to generate any unaligned
>>  # accesses
>> -ifneq ($(CONFIG_CPU_64),y)
>> +ifeq ($(CONFIG_CPU_32),y)
>>  KBUILD_CFLAGS += -mno-unaligned-access
>> -else
>> -KBUILD_CFLAGS += -mstrict-align
>>  endif
>> -
>> -# Prevent use of floating point and Advanced SIMD registers.
>>  ifeq ($(CONFIG_CPU_64),y)
>> +KBUILD_CFLAGS += -mstrict-align
>> +# Prevent use of floating point and Advanced SIMD registers.
>>  KBUILD_CFLAGS += -mgeneral-regs-only
>>  endif
>>
>> @@ -54,19 +53,11 @@ tune-$(CONFIG_CPU_ARM920T)  :=-
>> mtune=arm9tdmi
>>  tune-$(CONFIG_CPU_ARM926T)     :=-mtune=arm9tdmi
>>  tune-$(CONFIG_CPU_XSCALE)      :=$(call cc-option,-mtune=xscale,-
>> mtune=strongarm110) -Wa,-mcpu=xscale
>>
>> -ifeq ($(CONFIG_CPU_64), y)
>> -CFLAGS_ABI     :=-mabi=lp64
>> -else
>> -ifeq ($(CONFIG_AEABI),y)
>> -CFLAGS_ABI     :=-mabi=aapcs-linux
>> -else
>> -CFLAGS_ABI     :=$(call cc-option,-mapcs-32,-mabi=apcs-gnu) $(call cc-
>> option,-mno-thumb-interwork,)
>> -endif
>> -endif
>> +CFLAGS_ABI-$(CONFIG_CPU_64)    :=-mabi=lp64
>> +CFLAGS_ABI-$(CONFIG_CPU_32)    :=$(call cc-option,-mapcs-32,-mabi=apcs-
>> gnu) $(call cc-option,-mno-thumb-interwork,)
>> +CFLAGS_ABI-$(CONFIG_AEABI)     :=-mabi=aapcs-linux
>>
>> -ifeq ($(CONFIG_ARM_UNWIND),y)
>> -CFLAGS_ABI     +=-funwind-tables
>> -endif
>> +CFLAGS_ABI-$(CONFIG_ARM_UNWIND)        +=-funwind-tables
>>
>>  ifeq ($(CONFIG_THUMB2_BAREBOX),y)
>>  AFLAGS_AUTOIT  :=$(call as-option,-Wa$(comma)-mimplicit-it=always,-
>> Wa$(comma)-mauto-it)
>> @@ -75,13 +66,15 @@ CFLAGS_THUMB2       :=-mthumb $(AFLAGS_AUTOIT)
>> $(AFLAGS_NOWARN)
>>  AFLAGS_THUMB2  :=$(CFLAGS_THUMB2) -Wa$(comma)-mthumb
>>  endif
>>
>> +KBUILD_CPPFLAGS += $(CFLAGS_ABI-y) $(arch-y) $(tune-y)
>> +
>>  ifeq ($(CONFIG_CPU_64), y)
>> -KBUILD_CPPFLAGS += $(CFLAGS_ABI) $(arch-y) $(tune-y)
>>  KBUILD_AFLAGS   += -include asm/unified.h
>>  export S64_32 = 64
>>  export S64 = 64
>> -else
>> -KBUILD_CPPFLAGS += $(CFLAGS_ABI) $(arch-y) $(tune-y)
>> $(CFLAGS_THUMB2)
>> +endif
>> +ifeq ($(CONFIG_CPU_32), y)
>> +KBUILD_CPPFLAGS += $(CFLAGS_THUMB2)
>>  KBUILD_AFLAGS   += -include asm/unified.h -msoft-float $(AFLAGS_THUMB2)
>>  export S64_32 = 32
>>  export S32 = 32
>> --
>> 2.39.2
> 

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