[Buildroot] Using CFLAGS_MODULE in linux.mk

[John O'Sullivan]

Hi,
I am trying to build a kernel module that can have a number of conditional compile options depending on the product variant I am building.
Outside of buildroot I can do



make ARCH=arm modules CFLAGS_MODULE=-DVARIANT_PPG


The module picks up the VARIANT_PPG and I can conditionally build the module.
I am trying to do something similar in buildroot (2013-05). To test this out I tried amending the linux.mk file as follows:


LINUX_MAKE_FLAGS+=CFLAGS_MODULE=-DVARIANT_PPG




However when I add this line to linux.mk the variable VARIANT_PPG never seems to be seen in the module.
Has anyone any suggestions? Is there a reason its not working in the .mk file.
Is there a better way of doing this?


regards
John


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