[U-Boot] [RFC PATCH] Kbuild: introduce Makefile in arch/$ARCH/

[Daniel Schwierzeck <daniel.schwierzeck@gmail.com>]

Hi Masahiro,

On 21.11.2014 04:48, Masahiro Yamada wrote:
> Hi Daniel,
> 
> 
> On Wed, 19 Nov 2014 21:12:14 +0100
> Daniel Schwierzeck <daniel.schwierzeck@gmail.com> wrote:
> 
>> Introduce a Makefile under arch/$ARCH/ and include it in the
>> top Makefile (similar to Linux kernel). This allows further
>> refactoringi like moving architecture-specific code out of global
>> makefiles, deprecating config variables (CPU, CPUDIR, SOC) or
>> deprecating arch/$ARCH/config.mk.
>>
>> In contrary to Linux kernel, U-Boot defines the ARCH variable by
>> Kconfig, thus the arch Makefile can only included conditionally
>> after the top config.mk.
>>
>> Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
> 
> 
> I guess this patch is the one you mentioned on the way to the station
> after the u-boot mini summit.

yes

> 
> I think basically this is a good step forward
> although we need more efforts if we want to deprecate
> arch/$ARCH/cpu/$CPU/config.mk, board/$BOARD/config.mk as well.
> 
> 
> Some comments below.
> 
> I will probably ack it if you send v2.
> 
> 
> 
> 
> 
>> This patch should not cause any functional changes. It is compile-tested
>> on sandbox, aarch64, arm, mips, powerpc and x86.
> 
> This patch looks good for the other architecture, too.
> 
> 
> 
>> diff --git a/Makefile b/Makefile
>> index 590fec8..a2783ca 100644
>> --- a/Makefile
>> +++ b/Makefile
>> @@ -359,7 +359,7 @@ UBOOTRELEASE = $(shell cat include/config/uboot.release 2> /dev/null)
>>  UBOOTVERSION = $(VERSION)$(if $(PATCHLEVEL),.$(PATCHLEVEL)$(if $(SUBLEVEL),.$(SUBLEVEL)))$(EXTRAVERSION)
>>  
>>  export VERSION PATCHLEVEL SUBLEVEL UBOOTRELEASE UBOOTVERSION
>> -export ARCH CPU BOARD VENDOR SOC CPUDIR BOARDDIR
>> +export ARCH CPU BOARD VENDOR SOC CPUDIR BOARDDIR SPL_START_S_PATH
>>  export CONFIG_SHELL HOSTCC HOSTCFLAGS HOSTLDFLAGS CROSS_COMPILE AS LD CC
>>  export CPP AR NM LDR STRIP OBJCOPY OBJDUMP
>>  export MAKE AWK PERL PYTHON
> 
> 
> Why do you need to export SPL_START_S_PATH?
> It is unnecessary, I think.
> 

boards form ARM and PowerPC defined CONFIG_SPL_START_S_PATH so I moved
it to config.mk and made it consistent with the other variables. But if
only some ARM boards really use it, it is unnecessary.

> 
> 
> 
>> index 0000000..117ed30
>> --- /dev/null
>> +++ b/arch/arm/Makefile
>> @@ -0,0 +1,29 @@
>> +#
>> +# SPDX-License-Identifier:	GPL-2.0+
>> +#
>> +
>> +head-y := arch/arm/cpu/$(CPU)/start.o
>> +
>> +ifeq ($(CONFIG_SPL_BUILD),y)
>> +ifneq ($(SPL_START_S_PATH),)
>> +head-y := $(SPL_START_S_PATH)/start.o
>> +endif
>> +endif
> 
> 
> Because only some ARM boards are using CONFIG_SPL_START_S_PATH,
> perhaps we can directly handle it in arch/arm/Makefile and remove it from config.mk
> 
> ifeq ($(CONFIG_SPL_BUILD),y)
> ifneq ($(CONFIG_SPL_START_S_PATH),)
> head-y := $(CONFIG_SPL_START_S_PATH:"%"=%)/start.o
> endif
> endif
> 
> 
> 
> 
>> diff --git a/config.mk b/config.mk
>> index 64c2951..b957c1d 100644
>> --- a/config.mk
>> +++ b/config.mk
>> @@ -31,6 +31,9 @@ endif
>>  ifneq ($(CONFIG_SYS_SOC),)
>>  SOC := $(CONFIG_SYS_SOC:"%"=%)
>>  endif
>> +ifneq ($(CONFIG_SPL_START_S_PATH),)
>> +SPL_START_S_PATH := $(CONFIG_SPL_START_S_PATH:"%"=%)
>> +endif
> 
> 
> Can we remove this?

Yes, I will move it to arch/arm/Makefile

-- 
- Daniel