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/Makefile b/Makefile
index 9e148fb..7b4e4f6 100644
--- a/Makefile
+++ b/Makefile
@@ -397,6 +397,9 @@
$(eval $(call assert_boolean,TRUSTED_BOARD_BOOT))
$(eval $(call assert_boolean,USE_COHERENT_MEM))
+$(eval $(call assert_numeric,ARM_ARCH_MAJOR))
+$(eval $(call assert_numeric,ARM_ARCH_MINOR))
+
################################################################################
# Add definitions to the cpp preprocessor based on the current build options.
# This is done after including the platform specific makefile to allow the
@@ -404,6 +407,8 @@
################################################################################
$(eval $(call add_define,ARM_CCI_PRODUCT_ID))
+$(eval $(call add_define,ARM_ARCH_MAJOR))
+$(eval $(call add_define,ARM_ARCH_MINOR))
$(eval $(call add_define,ARM_GIC_ARCH))
$(eval $(call add_define,ASM_ASSERTION))
$(eval $(call add_define,COLD_BOOT_SINGLE_CPU))