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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>
This commit is contained in:
Antonio Nino Diaz 2017-05-24 14:11:07 +01:00
parent ab1794f576
commit d77b98cabf
2 changed files with 9 additions and 1 deletions
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6
docs/auth-framework.md
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@ -909,9 +909,13 @@ int verify_hash(void *data_ptr, unsigned int data_len,
```
The key algorithm (rsa, ecdsa) must be specified in the build system using the
`MBEDTLS_KEY_ALG` variable, so the Makefile can include the corresponding
`TF_MBEDTLS_KEY_ALG` variable, so the Makefile can include the corresponding
sources in the build.
Note: If code size is a concern, the build option `MBEDTLS_SHA256_SMALLER` can
be defined in the platform Makefile. It will make mbed TLS use an implementation
of SHA-256 with smaller memory footprint (~1.5 KB less) but slower (~30%).
- - - - - - - - - - - - - - - - - - - - - - - - - -
_Copyright (c) 2015, ARM Limited and Contributors. All rights reserved._

4
plat/arm/common/arm_common.mk
View File

@ -76,6 +76,10 @@ ARM_XLAT_TABLES_LIB_V1 := 0
$(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