diff options
| author | Soby Mathew <soby.mathew@arm.com> | 2019-10-07 11:43:32 +0000 |
|---|---|---|
| committer | TrustedFirmware Code Review <review@review.trustedfirmware.org> | 2019-10-07 11:43:32 +0000 |
| commit | 5b567758bb880d3a4e4db1498cf903a14b504ce2 (patch) | |
| tree | 1f7f2dfdf62019c49009e3f52e5d85dc04b437b2 /docs | |
| parent | 81da28c2096ffbe3d8f077cf80e0ccc23f2a69db (diff) | |
| parent | c97cba4ea44910df1f7b1af5dba79013fb44c383 (diff) | |
Merge "Fix the CAS spinlock implementation" into integration
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 6dad3105..e540fd06 100644 --- a/docs/getting_started/user-guide.rst +++ b/docs/getting_started/user-guide.rst @@ -817,6 +817,10 @@ 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. |