diff options
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/design/firmware-design.rst | 7 | ||||
| -rw-r--r-- | docs/getting_started/user-guide.rst | 4 |
2 files changed, 9 insertions, 2 deletions
diff --git a/docs/design/firmware-design.rst b/docs/design/firmware-design.rst index dc082082..2cbd9c94 100644 --- a/docs/design/firmware-design.rst +++ b/docs/design/firmware-design.rst @@ -2540,8 +2540,11 @@ Armv8.1-A This Architecture Extension is targeted when ``ARM_ARCH_MAJOR`` >= 8, or when ``ARM_ARCH_MAJOR`` == 8 and ``ARM_ARCH_MINOR`` >= 1. -- The Compare and Swap instruction is used to implement spinlocks. Otherwise, - the load-/store-exclusive instruction pair is used. +- By default, a load-/store-exclusive instruction pair is used to implement + spinlocks. The ``USE_SPINLOCK_CAS`` build option when set to 1 selects the + spinlock implementation using the ARMv8.1-LSE Compare and Swap instruction. + Notice this instruction is only available in AArch64 execution state, so + the option is only available to AArch64 builds. Armv8.2-A ~~~~~~~~~ diff --git a/docs/getting_started/user-guide.rst b/docs/getting_started/user-guide.rst index 44bfb7a3..ae276f25 100644 --- a/docs/getting_started/user-guide.rst +++ b/docs/getting_started/user-guide.rst @@ -820,6 +820,10 @@ Common build options reduces SRAM usage. Refer to `Library at ROM`_ for further details. Default is 0. +- ``USE_SPINLOCK_CAS``: Setting this build flag to 1 selects the spinlock + implementation variant using the ARMv8.1-LSE compare-and-swap instruction. + Notice this option is experimental and only available to AArch64 builds. + - ``V``: Verbose build. If assigned anything other than 0, the build commands are printed. Default is 0. |