refactor(cpufeat): enable SYS_REG_TRACE for FEAT_STATE_CHECKED
At the moment we only support access to the trace unit by system
registers (SYS_REG_TRACE) to be either unconditionally compiled in, or
to be not supported at all.
Add support for runtime detection (ENABLE_SYS_REG_TRACE_FOR_NS=2), by
adding is_feat_sys_reg_trace_supported(). That function considers both
build time settings and runtime information (if needed), and is used
before we access SYS_REG_TRACE related registers.
The FVP platform decided to compile in support unconditionally (=1),
even though this is an optional feature, so it is not available with the
FVP model's default command line.
Change that to the now supported dynamic option (=2), so the right
decision can be made by the code at runtime.
Change-Id: I450a574a4f6bd9fc269887037049c94c906f54b2
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
diff --git a/docs/getting_started/build-options.rst b/docs/getting_started/build-options.rst
index 9415871..94c12de 100644
--- a/docs/getting_started/build-options.rst
+++ b/docs/getting_started/build-options.rst
@@ -1079,10 +1079,11 @@
``FEATURE_DETECTION`` mechanism. The default is 0 and it is automatically
disabled when the target architecture is AArch32.
-- ``ENABLE_SYS_REG_TRACE_FOR_NS``: Boolean option to enable trace system
+- ``ENABLE_SYS_REG_TRACE_FOR_NS``: Numeric value to enable trace system
registers access from NS ELs, NS-EL2 or NS-EL1 (when NS-EL2 is implemented
but unused). This feature is available if trace unit such as ETMv4.x, and
- ETE(extending ETM feature) is implemented. This flag is disabled by default.
+ ETE(extending ETM feature) is implemented. This flag can take the values
+ 0 to 2, to align with the ``FEATURE_DETECTION`` mechanism. The default is 0.
- ``ENABLE_TRF_FOR_NS``: Numeric value to enable trace filter control registers
access from NS ELs, NS-EL2 or NS-EL1 (when NS-EL2 is implemented but unused),