Introduce locking primitives using CAS instruction
The ARMv8v.1 architecture extension has introduced support for far
atomics, which includes compare-and-swap. Compare and Swap instruction
is only available for AArch64.
Introduce build options to choose the architecture versions to target
ARM Trusted Firmware:
- ARM_ARCH_MAJOR: selects the major version of target ARM
Architecture. Default value is 8.
- ARM_ARCH_MINOR: selects the minor version of target ARM
Architecture. Default value is 0.
When:
(ARM_ARCH_MAJOR > 8) || ((ARM_ARCH_MAJOR == 8) && (ARM_ARCH_MINOR >= 1)),
for AArch64, Compare and Swap instruction is used to implement spin
locks. Otherwise, the implementation falls back to using
load-/store-exclusive instructions.
Update user guide, and introduce a section in Firmware Design guide to
summarize support for features introduced in ARMv8 Architecture
Extensions.
Change-Id: I73096a0039502f7aef9ec6ab3ae36680da033f16
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>
diff --git a/make_helpers/defaults.mk b/make_helpers/defaults.mk
index 0b93dfc..b47ea46 100644
--- a/make_helpers/defaults.mk
+++ b/make_helpers/defaults.mk
@@ -1,5 +1,5 @@
#
-# Copyright (c) 2016, ARM Limited and Contributors. All rights reserved.
+# Copyright (c) 2016-2017, ARM Limited and Contributors. All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
@@ -44,6 +44,10 @@
# port can change this value if needed.
ARM_CCI_PRODUCT_ID := 400
+# ARM Architecture major and minor versions: 8.0 by default.
+ARM_ARCH_MAJOR := 8
+ARM_ARCH_MINOR := 0
+
# Determine the version of ARM GIC architecture to use for interrupt management
# in EL3. The platform port can change this value if needed.
ARM_GIC_ARCH := 2