Re: [Qemu-arm] [Qemu-devel] [PATCH 0/2] Fix compilation dependency issues of CONFIG_ARM_V7M

[Peter Maydell]

On 2 June 2017 at 16:49, Alex Bennée <address@hidden> wrote:
> Peter Maydell <address@hidden> writes:
>> We seem to run into "CONFIG_FOO is defined for make but not
>> for the C preprocessor" from time to time, so maybe we should
>> fix that?
>
> Hmm is should be auto-generated from config-(host|target).mak but I've
> never quite figured out why we need timestamps rather than a straight
> dependency check in rules.mk:
>
>   # Generate timestamp files for .h include files
>
>   config-%.h: config-%.h-timestamp
>           @cmp $< $@ >/dev/null 2>&1 || cp $< $@
>
>   config-%.h-timestamp: config-%.mak $(SRC_PATH)/scripts/create_config
>           $(call quiet-command, sh $(SRC_PATH)/scripts/create_config < $< > 
> $@,"GEN","$(TARGET_DIR)config-$*.h")
>
> This seems to be one of those things that goes away on a make clean && rebuild

Not the issue in this case -- what happens is that these CONFIG_*
defines are defined in config-devices.mak, but we don't have any
equivalent config-devices.h which would expose them to the C code.

(I assume the rules.mak stuff is attempting to avoid having a
not-an-actual-change to the .h file result in rebuilding the whole
world.)

thanks
-- PMM