diff options
| author | Ionela Voinescu <ionela.voinescu@arm.com> | 2020-03-05 09:06:24 +0000 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2020-03-06 16:02:50 +0000 |
| commit | 6abde90881a5ea3a383c0959fdd7f575f95db4b3 (patch) | |
| tree | 2826a354a232686de7316d55ff24f7b456279562 /Documentation/arm64/booting.rst | |
| parent | 4fcdf106a4330bb5c2306a1efbb3af3b7c0db537 (diff) | |
Documentation: arm64: document support for the AMU extension
The activity monitors extension is an optional extension introduced
by the ARMv8.4 CPU architecture.
Add initial documentation for the AMUv1 extension:
- arm64/amu.txt: AMUv1 documentation
- arm64/booting.txt: system registers initialisation
Signed-off-by: Ionela Voinescu <ionela.voinescu@arm.com>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'Documentation/arm64/booting.rst')
| -rw-r--r-- | Documentation/arm64/booting.rst | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/Documentation/arm64/booting.rst b/Documentation/arm64/booting.rst index 5d78a6f5b0ae..a3f1a47b6f1c 100644 --- a/Documentation/arm64/booting.rst +++ b/Documentation/arm64/booting.rst @@ -248,6 +248,20 @@ Before jumping into the kernel, the following conditions must be met: - HCR_EL2.APK (bit 40) must be initialised to 0b1 - HCR_EL2.API (bit 41) must be initialised to 0b1 + For CPUs with Activity Monitors Unit v1 (AMUv1) extension present: + - If EL3 is present: + CPTR_EL3.TAM (bit 30) must be initialised to 0b0 + CPTR_EL2.TAM (bit 30) must be initialised to 0b0 + AMCNTENSET0_EL0 must be initialised to 0b1111 + AMCNTENSET1_EL0 must be initialised to a platform specific value + having 0b1 set for the corresponding bit for each of the auxiliary + counters present. + - If the kernel is entered at EL1: + AMCNTENSET0_EL0 must be initialised to 0b1111 + AMCNTENSET1_EL0 must be initialised to a platform specific value + having 0b1 set for the corresponding bit for each of the auxiliary + counters present. + The requirements described above for CPU mode, caches, MMUs, architected timers, coherency and system registers apply to all CPUs. All CPUs must enter the kernel in the same exception level. |