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- .. SPDX-License-Identifier: CC-BY-SA-2.0-UK
- Using x32 psABI
- ***************
- x32 processor-specific Application Binary Interface (`x32
- psABI <https://software.intel.com/en-us/node/628948>`__) is a native
- 32-bit processor-specific ABI for Intel 64 (x86-64) architectures. An
- ABI defines the calling conventions between functions in a processing
- environment. The interface determines what registers are used and what
- the sizes are for various C data types.
- Some processing environments prefer using 32-bit applications even when
- running on Intel 64-bit platforms. Consider the i386 psABI, which is a
- very old 32-bit ABI for Intel 64-bit platforms. The i386 psABI does not
- provide efficient use and access of the Intel 64-bit processor
- resources, leaving the system underutilized. Now consider the x86_64
- psABI. This ABI is newer and uses 64-bits for data sizes and program
- pointers. The extra bits increase the footprint size of the programs,
- libraries, and also increases the memory and file system size
- requirements. Executing under the x32 psABI enables user programs to
- utilize CPU and system resources more efficiently while keeping the
- memory footprint of the applications low. Extra bits are used for
- registers but not for addressing mechanisms.
- The Yocto Project supports the final specifications of x32 psABI as
- follows:
- - You can create packages and images in x32 psABI format on x86_64
- architecture targets.
- - You can successfully build recipes with the x32 toolchain.
- - You can create and boot ``core-image-minimal`` and
- ``core-image-sato`` images.
- - There is RPM Package Manager (RPM) support for x32 binaries.
- - There is support for large images.
- To use the x32 psABI, you need to edit your ``conf/local.conf``
- configuration file as follows::
- MACHINE = "qemux86-64"
- DEFAULTTUNE = "x86-64-x32"
- baselib = "${@d.getVar('BASE_LIB:tune-' + (d.getVar('DEFAULTTUNE') \
- or 'INVALID')) or 'lib'}"
- Once you have set
- up your configuration file, use BitBake to build an image that supports
- the x32 psABI. Here is an example::
- $ bitbake core-image-sato
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