Make device tree pre-processing similar to U-boot/Linux

Following changes are done to make DT pre-processing similar to that of
U-boot/Linux kernel.

1. Creating seperate CPPFLAGS for DT preprocessing so that compiler
options specific to it can be accommodated.
e.g: "-undef" compiler option avoids replacing "linux" string(used in
device trees) with "1" as "linux" is a pre-defined macro in gnu99

2. Replace CPP with PP for DT pre-processing, as CPP in U-boot/Linux is
exported as "${CROSS_COMPILE}gcc -E" while in TF-A it is exported as

Change-Id: If4c61a249d51614d9f53ae30b602036d50c02349
Signed-off-by: Manish Pandey <>
2 files changed