[U-Boot] RFC: auto-generate ARM mach-types.h file from ARM machine database

[Michael Schwingen <rincewind@discworld.dascon.de>]

Am 05/06/2011 07:09 AM, schrieb Mike Frysinger:
> On Thu, May 5, 2011 at 17:48, Michael Schwingen wrote:
>> --- a/Makefile
>> +++ b/Makefile
>> @@ -469,7 +469,7 @@ $(obj)System.map:   $(obj)u-boot
>>  # This target actually generates 2 files; autoconf.mk and autoconf.mk.dep.
>>  # the dep file is only include in this top level makefile to determine when
>>  # to regenerate the autoconf.mk file.
>> -$(obj)include/autoconf.mk.dep: $(obj)include/config.h include/common.h
>> +$(obj)include/autoconf.mk.dep: $(obj)include/config.h include/common.h $(obj)include/asm/mach-types.h
>>        @$(XECHO) Generating $@ ; \
>>        set -e ; \
>>        : Generate the dependancies ; \
>> @@ -530,13 +530,18 @@ unconfig:
>>                $(obj)board/*/config.tmp $(obj)board/*/*/config.tmp \
>>                $(obj)include/autoconf.mk $(obj)include/autoconf.mk.dep
>>
>> -%_config::     unconfig
>> +%_config::     unconfig $(obj)include/asm/mach-types.h
>>        @$(MKCONFIG) -A $(@:_config=)
>>
>>  sinclude $(obj).boards.depend
>>  $(obj).boards.depend:  boards.cfg
>>        awk '(NF && $$1 !~ /^#/) { print $$1 ": " $$1 "_config; $$(MAKE)" }' $< > $@
>>
>> +
>> +$(obj)include/asm/mach-types.h: arch/arm/tools/gen-mach-types arch/arm/tools/mach-types
>> +       @mkdir -p $(obj)include/asm
>> +       awk -f $^ > $@ || { rm -f $@; /bin/false; }
>> +
>>  #
>>  # Functions to generate common board directory names
>>  #
> this all belongs in arch/arm/config.mk and not the toplevel makefile
Fine with me, however, I am hitting a big problem with the Makefile
structure:

mach-types.h needs to be built before autoconf.mk can be generated, and
the rules for autoconf.mk are in the top-level Makefile.

If I put rules in arch/arm/config.mk, then the first of these rules
becomes the default rule which is executed in subdir makes (like "make
-C arch"), which breaks compilation completely, since config.mk is
included before the rules are defined in the subdir Makefiles.

It seems the current scheme allows only variable definitions in
config.mk files, which is not sufficient here.

rules.mk would be fine, however, there is no provision to include rules
from lower directories, since all the building in subdirectories is
handled by recursively calling make (this is one of the problems that
arise by recursively calling make for each directory, but that is a
different topic).

Any ideas? Using the current Makefile structure, I see no other solution
than defining the mach-types.h generation rules in the toplevel Makefile.

> also, dont hardcode full paths to things.  there's no reason for it.
Which of these can be omitted?

When putting the rules in arch/arm/config.mk, I can make them trigger
only when compiling for ARM, and I can use $(ARCH) instead of  arm/, but
apart from that, I think I need to specify the paths, no?

> might want to add an "update-mach-types" target so people can type
> `make update-mach-types` and it'll automatically wget the right file
> to the right place ...
Good idea.
I agree with Wolfgang that this is intended to be used by the maintainer
mainly, so the mach-types file should be included in the source so that
a normal user does not need to download the file.

cu
Michael