754345d606
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 (From OE-Core rev: db1b355b2b15ba57bd89c2dfb88c2c667551863e) 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>
2012/03/30 - Mark Hatle mark.hatle@windriver.com
- Initial Revision
Introduction
The individual CPU, and ABI tunings are contained in this directory. A number of local and global variables are used to control the way the tunings are setup and how they work together to specify an optimized configuration.
The following is brief summary of the generic components that are used in these tunings.
AVAILTUNES - This is a list of all of the tuning definitions currently available in the system. Not all tunes in this list may be compatible with the machine configuration, or each other in a multilib configuration. Each tuning file can add to this list using "+=", but should never replace the list using "=".
DEFAULTTUNE - This specifies the tune to use for a particular build. Each tune should specify a reasonable default, which can be overriden by a machine or multilib configuration. The specified tune must be listed in the AVAILTUNES.
TUNEVALID[feature] - The is defined with a human readable explanation for what it does. All architectural, cpu, abi, etc tuning features must be defined using TUNEVALID.
TUNECONFLICTS[feature] - A list of features which conflict with . New sanity checks will try to reject combinations in which a single tuning ends up with features which conflict with each other.
TUNE_FEATURES - This is automatically defined as TUNE_FEATURES:tune-. See TUNE_FEATURES:tune- for more information.
TUNE_FEATURES:tune- - Specify the features used to describe a specific tune. This is a list of features that a tune support, each feature must be in the TUNEVALID list. Note: the tune and a given feature name may be the same, but they have different purposes. Only features may be used to change behavior, while tunes are used to describe an overall set of features.
ABIEXTENSION - An ABI extension may be specified by a specific feature or other tuning setting, such as TARGET_FPU. Any ABI extensions either need to be defined in the architectures base arch file, i.e. ABIEXTENSION = "eabi" in the arm case, or appended to in specific tune files with a ".=". Spaces are not allowed in this variable.
TUNE_CCARGS - Setup the cflags based on the TUNE_FEATURES settings. These should be additive when defined using "+=". All items in this list should be dynamic! i.e. ${@bb.utils.contains("TUNE_FEATURES", "feature", "cflag", "!cflag", d)}
TUNE_ARCH - The GNU canonical arch for a specific architecture. i.e. arm, armeb, mips, mips64, etc. This value is used by bitbake to setup configure. TUNE_ARCH definitions are specific to a given architecture. They may be a single static definition, or may be dynamically adjusted. See each architecture's README for details for that CPU family.
TUNE_PKGARCH - The package architecture used by the packaging systems to define the architecture, abi and tuning of a particular package. Similarly to TUNE_ARCH, the definition of TUNE_PKGARCH is specific to each architecture. See each architectures README for details for that CPU family.
PACKAGE_EXTRA_ARCHS - Lists all runtime compatible package architectures. By default this is equal to PACKAGE_EXTRA_ARCHS:tune-. If an architecture deviates from the default it will be listed in the architecture README.
PACKAGE_EXTRA_ARCHS:tune- - List all of the package architectures that are compatible with this specific tune. The package arch of this tune must be in the list.
TARGET_FPU - The FPU setting for a given tune, hard (generate floating point instructions), soft (generate internal gcc calls), "other" architecture specific floating point. This is synchronized with the compiler and other toolchain items. This should be dynamically configured in the same way that TUNE_CCARGS is.
BASE_LIB:tune- - The "/lib" location for a specific ABI. This is used in a multilib configuration to place the libraries in the correct, non-conflicting locations.
Best Practice
The tune infrastructure is designed to be hierarchical. When writing a new tune file for a "fast-forward" CPU architecture (one that supports everything from a previous generation), it is recommended to require the previous generation tune file and specify PACKAGE_EXTRA_ARCHS using the previous generation's override and appending the new tune. Note that only one previous tune file should be included to avoid mutiple includes of the base arch which could lead to a broken configuration due to multiple prepend and append assignments.
For example, for x86, there is a common x86/arch-x86.inc which is included in the base i586 tune file. The core2 tune builds on that, and corei7 builds on core2.