1 files changed, 44 insertions, 0 deletions

diff --git a/meta/conf/machine/include/arm/feature-arm-thumb.inc b/meta/conf/machine/include/arm/feature-arm-thumb.inc
new file mode 100644
index 0000000000..a94386f577
--- /dev/null
+++ b/meta/conf/machine/include/arm/feature-arm-thumb.inc
@@ -0,0 +1,44 @@
+# The instruction set the compiler should use when generating application
+# code. The kernel is always compiled with arm code at present. arm code
+# is the original 32 bit ARM instruction set, thumb code is the 16 bit
+# encoded RISC sub-set. Thumb code is smaller (maybe 70% of the ARM size)
+# but requires more instructions (140% for 70% smaller code) so may be
+# slower.
+TUNEVALID[thumb] = "Use thumb instructions instead of ARM"
+ARM_THUMB_OPT = "${@['arm', 'thumb'][d.getVar('ARM_INSTRUCTION_SET', True) == 'thumb']}"
+ARM_THUMB_SUFFIX .= "${@bb.utils.contains('TUNE_FEATURES', 'armv4',  't',  '', d)}"
+ARM_THUMB_SUFFIX .= "${@bb.utils.contains('TUNE_FEATURES', 'armv5',  't',  '', d)}"
+ARM_THUMB_SUFFIX .= "${@bb.utils.contains('TUNE_FEATURES', 'armv6',  't',  '', d)}"
+ARM_THUMB_SUFFIX .= "${@bb.utils.contains('TUNE_FEATURES', 'armv7a', 't2', '', d)}"
+ARM_THUMB_SUFFIX .= "${@bb.utils.contains('TUNE_FEATURES', 'armv7r', 't2', '', d)}"
+ARM_THUMB_SUFFIX .= "${@bb.utils.contains('TUNE_FEATURES', 'armv7m', 't2', '', d)}"
+
+# If the device supports ARM, then respect ARM_THUMB_OPT (which can be "arm" or "thumb")
+# If the defice doesn't support ARM, then always set "thumb" even when
+# some recipe explicitly sets ARM_INSTRUCTION_SET to "arm"
+ARM_M_OPT = "${@bb.utils.contains('TUNE_FEATURES', 'arm', '${ARM_THUMB_OPT}', 'thumb', d)}"
+python () {
+    selected = d.getVar('ARM_INSTRUCTION_SET', True)
+    if selected == None:
+        return
+    used = d.getVar('ARM_M_OPT', True)
+    if selected != used:
+        pn = d.getVar('PN', True)
+        bb.warn("Recipe '%s' selects ARM_INSTRUCTION_SET to be '%s', but tune configuration overrides it to '%s'" % (pn, selected, used))
+}
+
+TUNE_CCARGS .= "${@bb.utils.contains('TUNE_FEATURES', 'thumb', ' -m${ARM_M_OPT}', '', d)}"
+OVERRIDES .= "${@bb.utils.contains('TUNE_FEATURES', 'thumb', ':thumb', '', d)}"
+
+ARMPKGSFX_THUMB .= "${@bb.utils.contains('TUNE_FEATURES', 'thumb', '${ARM_THUMB_SUFFIX}', '', d)}"
+
+# Whether to compile with code to allow interworking between the two
+# instruction sets. This allows thumb code to be executed on a primarily
+# arm system and vice versa. It is strongly recommended that DISTROs not
+# turn this off - the actual cost is very small.
+TUNEVALID[no-thumb-interwork] = "Disable mixing of thumb and ARM functions"
+TUNE_CCARGS .= "${@bb.utils.contains('TUNE_FEATURES', 'no-thumb-interwork', ' -mno-thumb-interwork', ' -mthumb-interwork', d)}"
+OVERRIDES .= "${@bb.utils.contains('TUNE_FEATURES', 'no-thumb-interwork', ':thumb-interwork', '', d)}"
+
+# what about armv7m devices which don't support -marm (e.g. Cortex-M3)?
+TARGET_CC_KERNEL_ARCH += "-mno-thumb-interwork -marm"