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Andre McCurdy
3e7d26e31a
Although there may still be specific cases which can benefit from the ARM instruction set, the Thumb2 instruction set is generally a better default for armv7a class CPUs. Distros such as Debian and Fedora have been targeting Thumb2 by default for some time. Note that setting ARM_INSTRUCTION_SET has no effect unless TUNE_FEATURES contains "thumb" (which is controlled by the "t" suffix in DEFAULTTUNE, e.g. armv7vehf-neon -vs- armv7vethf-neon, etc) so out of tree machine configs may need to update their DEFAULTTUNE to take advantage of this change. (From OE-Core rev: c88304a78e528596ca481cabe273749c286c352a) Signed-off-by: Andre McCurdy <armccurdy@gmail.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
2012/03/30 - Mark Hatle <mark.hatle@windriver.com>
- Initial Revision
The ARM architecture definitions are split among a number of files.
The primary definitions for the variables are handled by the core
arch-arm.inc file.
TUNE_ARCH is set to either "arm" or "armeb" depending on the value
of the existence of the "bigendian" feature in a given tune.
A small set of ARM specific variables have been defined to allow
TUNE_PKGARCH to be automatically defined. Optimized tunings must NOT
change the definiton of TUNE_PKGARCH. TUNE_PKGACH_tune-<tune> will be
ignored. The format of the package arch is enforced by the TUNE_PKGARCH
default. The format must be of the form:
<armversion>[t][e][hf][b][-vfp][-neon]
TUNE_PKGARCH is defined as:
${ARMPKGARCH}${ARMPKGSFX_THUMB}${ARMPKGSFX_DSP}${ARMPKGSFX_EABI}${ARMPKGSFX_ENDIAN}${ARMPKGSFX_FPU}
ARMPKGARCH - This is the core package arch component specified by each
tuning. This is the primary identifier of a tuning. Usual values are:
arm, armv4, armv5, armv6, armv7a, etc.
ARMPKGSFX_THUMB - This is the thumb specific suffix. Curently it is
defined in feature-arm-thumb.inc.
ARMPKGSFX_DSP - This is the DSP specific suffix. Currently this is set
to 'e' when on armv5 and the dsp feature is enabled.
ARMPKGSFX_EABI - This is the eabi specific suffix. There are currently
two defined ABIs specificed, standard EABI and Hard Float (VFP) EABI.
When the callconvention-hard is enabled, "hf" is specified, otherwise it
is blank.
ARMPKGSFX_ENDIAN - This is the endian specific suffix. It is defined in
the core arch-arm.inc file.
ARMPKGSFX_FPU - This is the FPU specific suffix. The suffix indicates
specific FPU optimizations. 'vfp' and 'neon' are both defined.