mbedtls: Use `MBEDTLS_SHA256_SMALLER` in ARM platforms
This options enables an implementation of SHA-256 that has a smaller
code footprint (~1.6 KB less) but is also ~30% slower. For ARM
platforms, code size is currently considered more important than
execution speed in the mbed TLS crypto module.
Added a small note about this option to the documentation of the
authentication framework.
Change-Id: I4c0b221ea5d3466465261316ba07b627fa01b233
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
diff --git a/plat/arm/common/arm_common.mk b/plat/arm/common/arm_common.mk
index 58fc94e..38c8cf8 100644
--- a/plat/arm/common/arm_common.mk
+++ b/plat/arm/common/arm_common.mk
@@ -76,6 +76,10 @@
$(eval $(call assert_boolean,ARM_XLAT_TABLES_LIB_V1))
$(eval $(call add_define,ARM_XLAT_TABLES_LIB_V1))
+# Use an implementation of SHA-256 with a smaller memory footprint but reduced
+# speed.
+$(eval $(call add_define,MBEDTLS_SHA256_SMALLER))
+
# Enable PSCI_STAT_COUNT/RESIDENCY APIs on ARM platforms
ENABLE_PSCI_STAT := 1
ENABLE_PMF := 1