feature-arm-crypto: Add +nocrypto to -mcpu when crypto not in features

When crypto is not in tune features then add +nocryto to
-mcpu explicitly. This makes the behavior between clang
and gcc match. Currently -mcpu=cortex-a72 has different
behavior in clang and gcc in terms of what features are
considered default. Clang enables different set of common
features than gcc on other hand. For example clang
enables crypto with default set but gcc
does not, gcc recommends to disable unavailable extensions
in -mcpu [1] explicitly. crypto is optional on cortex-a53
and cortex-a72. This is not as common but Broadcom
SOCs in raspberrypi3/4 have dropped crypto for cost
reasons [2]. This results in illegal instruction
traps [3] [4] when building components e.g. chromium,
qtwebengine, weston etc. with clang using -mcpu=cortex-a72
for rpi4 target.

Adding +nocrypto makes clang behave like gcc does today. We
do have separate tune if crypto enabled cortex-a72 cores
are to be targeted (cortexa72-cryto) as DEFAULTTUNE

They are added to default feature file since crypto extension
is available in multiple arm architecture versions e.g. armv8,
armv9. It is optional extension as per spec [5]

Extensions can be enabled and disabled with -mcpu using the same
syntax as with -march, and have same effect thats why it is
intrumented via TUNE_CCARGS_MARCH_OPTS

[1] https://gcc.gnu.org/onlinedocs/gcc/ARM-Options.html#index-mcpu-2
[2] https://forums.raspberrypi.com/viewtopic.php?f=63&t=207888#p1332960
[3] https://github.com/llvm/llvm-project/issues/85699
[4] https://github.com/llvm/llvm-project/issues/90365
[5] https://developer.arm.com/documentation/109697/2025_06/Feature-descriptions/The-Armv9-0-architecture-extension

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Cc: Quentin Schulz <quentin.schulz@cherry.de>
Acked-by: Quentin Schulz <quentin.schulz@cherry.de>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

diff --git a/meta/conf/machine/include/arm/feature-arm-crypto.inc b/meta/conf/machine/include/arm/feature-arm-crypto.inc
index aade6ce08d5ee96bd34833e2843b5cabf676dac9..8202de78e46e6e1625d5e0d4565edec015093a16 100644 (file)
--- a/meta/conf/machine/include/arm/feature-arm-crypto.inc
+++ b/meta/conf/machine/include/arm/feature-arm-crypto.inc
@@ -2,4 +2,5 @@
 # armv8-a, armv8.1-a, armv8.3-a, armv8.4-a, armv8.5-a, armv8.6-a, and armv8-r
 
 TUNEVALID[crypto] = "Enable cryptographic instructions for ARMv8"
-TUNE_CCARGS_MARCH_OPTS .= "${@bb.utils.contains('TUNE_FEATURES', 'crypto', '+crypto', '', d)}"
+# See  https://github.com/llvm/llvm-project/issues/85699
+TUNE_CCARGS_MARCH_OPTS .= "${@bb.utils.contains('TUNE_FEATURES', 'crypto', '+crypto', '+nocrypto', d)}"