build: Define build option for hardware-assisted coherency
The boolean build option HW_ASSISTED_COHERENCY is introduced to enable
various optimizations in ARM Trusted Software, when built for such
systems. It's set to 0 by default.
Change-Id: I638390da6e1718fe024dcf5b402e07084f1eb014
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>
diff --git a/Makefile b/Makefile
index 932fb3b..e00159a 100644
--- a/Makefile
+++ b/Makefile
@@ -385,6 +385,7 @@
$(eval $(call assert_boolean,ENABLE_RUNTIME_INSTRUMENTATION))
$(eval $(call assert_boolean,ERROR_DEPRECATED))
$(eval $(call assert_boolean,GENERATE_COT))
+$(eval $(call assert_boolean,HW_ASSISTED_COHERENCY))
$(eval $(call assert_boolean,LOAD_IMAGE_V2))
$(eval $(call assert_boolean,NS_TIMER_SWITCH))
$(eval $(call assert_boolean,PL011_GENERIC_UART))
@@ -419,6 +420,7 @@
$(eval $(call add_define,ENABLE_PSCI_STAT))
$(eval $(call add_define,ENABLE_RUNTIME_INSTRUMENTATION))
$(eval $(call add_define,ERROR_DEPRECATED))
+$(eval $(call add_define,HW_ASSISTED_COHERENCY))
$(eval $(call add_define,LOAD_IMAGE_V2))
$(eval $(call add_define,LOG_LEVEL))
$(eval $(call add_define,NS_TIMER_SWITCH))
diff --git a/docs/user-guide.md b/docs/user-guide.md
index 091aeba..4ed0e20 100644
--- a/docs/user-guide.md
+++ b/docs/user-guide.md
@@ -328,6 +328,15 @@
* `HANDLE_EA_EL3_FIRST`: When defined External Aborts and SError Interrupts
will be always trapped in EL3 i.e. in BL31 at runtime.
+* `HW_ASSISTED_COHERENCY`: On most ARM systems to-date, platform-specific
+ software operations are required for CPUs to enter and exit coherency.
+ However, there exists newer systems where CPUs' entry to and exit from
+ coherency is managed in hardware. Such systems require software to only
+ initiate the operations, and the rest is managed in hardware, minimizing
+ active software management. In such systems, this boolean option enables ARM
+ Trusted Firmware to carry out build and run-time optimizations during boot
+ and power management operations. This option defaults to 0.
+
* `LOAD_IMAGE_V2`: Boolean option to enable support for new version (v2) of
image loading, which provides more flexibility and scalability around what
images are loaded and executed during boot. Default is 0.
diff --git a/make_helpers/defaults.mk b/make_helpers/defaults.mk
index b47ea46..de506be 100644
--- a/make_helpers/defaults.mk
+++ b/make_helpers/defaults.mk
@@ -105,6 +105,10 @@
# For Chain of Trust
GENERATE_COT := 0
+# Whether system coherency is managed in hardware, without explicit software
+# operations.
+HW_ASSISTED_COHERENCY := 0
+
# Flag to enable new version of image loading
LOAD_IMAGE_V2 := 0