feat(qemu): allow ARM_ARCH_MAJOR/MINOR override

An upcoming change to the RME support code will use atomic instructions
introduced in Armv8.1 in order to implement bitlocks. In order to do
this, the code needs to be built with appropriate -march compiler flag
(otherwise the assembler complains about invalid instructions). One way
to do this is specifying ARM_ARCH_MAJOR/MINOR version greater than 8.0,
which is what the main Makefile does when ENABLE_RME is set.

Allow the main Makefile to override the ARM_ARCH_MAJOR/MINOR variables
on the QEMU platform, so that it can also build the bitlock functions.

This only affects firmware built with ENABLE_RME, which is an
experimental feature both in TF-A and QEMU. The QEMU platform code
doesn't support booting an ENABLE_RME firmware on non-RME CPUs at the
moment.

As a result of this change, when ENABLE_RME is set,
make_helpers/arch_features.mk sets ENABLE_TRF_FOR_NS to 1, which needs
to be overridden by the QEMU Makefile.

Change-Id: I695fc98b21d07f6c84003d9e36a57cad2a3c806e
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
1 file changed