feat(d128): add support for FEAT_D128
This patch disables trapping to EL3 when the FEAT_D128
specific registers are accessed by setting the SCR_EL3.D128En bit.
If FEAT_D128 is implemented, then FEAT_SYSREG128 is implemented.
With FEAT_SYSREG128 certain system registers are treated as 128-bit,
so we should be context saving and restoring 128-bits instead of 64-bit
when FEAT_D128 is enabled.
FEAT_SYSREG128 adds support for MRRS and MSRR instruction which
helps us to read write to 128-bit system register.
Refer to Arm Architecture Manual for further details.
Change the FVP platform to default to handling this as a dynamic option
so the right decision can be made by the code at runtime.
Change-Id: I1a53db5eac29e56c8fbdcd4961ede3abfcb2411a
Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
Signed-off-by: Govindraj Raja <govindraj.raja@arm.com>
diff --git a/docs/getting_started/build-options.rst b/docs/getting_started/build-options.rst
index 7776f5b..772447a 100644
--- a/docs/getting_started/build-options.rst
+++ b/docs/getting_started/build-options.rst
@@ -471,6 +471,15 @@
This flag can take the values 0 to 2, to align with the ``ENABLE_FEAT``
mechanism. Default value is ``0``.
+- ``ENABLE_FEAT_D128``: Numeric value to enable support for FEAT_D128
+ at EL2 and below, setting the bit SCT_EL3.D128En in EL3 to allow access to
+ 128 bit version of system registers like PAR_EL1, TTBR0_EL1, TTBR1_EL1,
+ TTBR0_EL2, TTBR1_EL2, TTBR0_EL12, TTBR1_EL12 , VTTBR_EL2, RCWMASK_EL1, and
+ RCWSMASK_EL1. Its an optional architectural feature and is available from
+ 9.3 and upwards.
+ This flag can take the values 0 to 2, to align with the ``ENABLE_FEAT``
+ mechanism. Default value is ``0``.
+
- ``ENABLE_LTO``: Boolean option to enable Link Time Optimization (LTO)
support in GCC for TF-A. This option is currently only supported for
AArch64. Default is 0.