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| author | Andre Przywara <andre.przywara@arm.com> | 2022-11-17 16:42:09 +0000 |
|---|---|---|
| committer | Andre Przywara <andre.przywara@arm.com> | 2023-03-22 13:33:22 +0000 |
| commit | 240770989f618da1b015f9a580fe0c83e10688a2 (patch) | |
| tree | 4a0518de3915a93f87acb2a373a1f399a8b7f5c1 /docs/getting_started/build-options.rst | |
| parent | 387b8801f956204b2970a5b65de0f9ad6821a4b7 (diff) | |
| download | arm-trusted-firmware-240770989f618da1b015f9a580fe0c83e10688a2.tar.gz | |
refactor(cpufeat): align FEAT_SB to new feature handling
FEAT_SB introduces a new speculation barrier instruction, that is more
lightweight than a "dsb; isb" combination. We use that in a hot path,
so cannot afford and don't want a runtime detection mechanism.
Nevertheless align the implementation of the feature detection part
with the other features, but renaming the detection function, and
updating the FEAT_DETECTION code. Also update the documentation.
Change-Id: I2b86dfd1ad259c3bb99ab5186e2911ace454b54c
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Diffstat (limited to 'docs/getting_started/build-options.rst')
| -rw-r--r-- | docs/getting_started/build-options.rst | 11 |
1 files changed, 5 insertions, 6 deletions
diff --git a/docs/getting_started/build-options.rst b/docs/getting_started/build-options.rst index 94c12defe..0540b6d2f 100644 --- a/docs/getting_started/build-options.rst +++ b/docs/getting_started/build-options.rst @@ -327,12 +327,11 @@ Common build options Default value is ``0``. ``FEAT_RNG_TRAP`` is an optional feature from Armv8.5 onwards. -- ``ENABLE_FEAT_SB``: Numeric value to enable the ``FEAT_SB`` (Speculation - Barrier) extension allowing access to ``sb`` instruction. ``FEAT_SB`` is an - optional feature and defaults to ``0`` for pre-Armv8.5 CPUs but are mandatory - for Armv8.5 or later CPUs. This flag can take values 0 to 2, to align with - ``FEATURE_DETECTION`` mechanism. It is enabled from v8.5 and upwards and if - needed could be overidden from platforms explicitly. Default value is ``0``. +- ``ENABLE_FEAT_SB``: Boolean option to let the TF-A code use the ``FEAT_SB`` + (Speculation Barrier) instruction ``FEAT_SB`` is an optional feature and + defaults to ``0`` for pre-Armv8.5 CPUs, but is mandatory for Armv8.5 or + later CPUs. It is enabled from v8.5 and upwards and if needed can be + overidden from platforms explicitly. - ``ENABLE_FEAT_SEL2``: Numeric value to enable the ``FEAT_SEL2`` (Secure EL2) extension. ``FEAT_SEL2`` is a mandatory feature available on Arm v8.4. |