fix(tc): enable dynamic feature detection of FEAT_SVE for NormalWorld

Currently, TF-A supports three states for feature flags:
1: FEAT_STATE_ALWAYS (for fixed/real platforms)
2: FEAT_STATE_CHECK  (for configurable platforms)
to meet the feature detection requirements dynamically, mainly
targetting configurable/Fixed Virtual platforms.

With this mechanism in place, we are refactoring all the existing
feature flags to the FEAT_STATE_CHECK option(=2), including
FEAT_SVE explicitly for FVPs.

SVE Patch Reference:

This newly introduced change, breaks the existing behaviour especially
for virtual platforms, who have set the ENABLE_SVE_FOR_NS flag to 1.

Moving ahead, we advise the platforms to take the following steps while
enabling the features:

1. If the platform is configurable (virtual), and want to ensure feature
detection happens dynamically at runtime, set the build flags to

2. For real(fixed) platforms, depending on the features supported by the
hardware and platform wants to enable it, platforms could set build
flags to FEAT_STATE_ALWAYS(=1).

(Note: Only the non-secure world enablement related build flags have
been refactored to take the values within 0 to 2. As earlier Secure
world enablement flags will still remain boolean.)

Henceforth, in order to keep it aligned with this tri-state mechanism,
changing the TC platform default to the now supported dynamic
option(=2), so the right decision can be made by the code at runtime.

Change-Id: I4c1ebeb55a00a7f148fac1573a6694b7c02a0a81
Signed-off-by: Jayanth Dodderi Chidanand <>
1 file changed