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-rw-r--r--conf/machine/include/tune-thumb.inc32
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diff --git a/conf/machine/include/tune-thumb.inc b/conf/machine/include/tune-thumb.inc
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+#tune file for thumb instructions
+
+ARM_INSTRUCTION_SET ?= "arm"
+# "arm" "thumb"
+# 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.
+
+THUMB_INTERWORK ?= "yes"
+# "yes" "no"
+# 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.
+
+OVERRIDE_THUMB = "${@['', ':thumb'][bb.data.getVar('ARM_INSTRUCTION_SET', d, 1) == 'thumb']}"
+OVERRIDE_INTERWORK = "${@['', ':thumb-interwork'][bb.data.getVar('THUMB_INTERWORK', d, 1) == 'yes']}"
+OVERRIDES .= "${OVERRIDE_THUMB}${OVERRIDE_INTERWORK}"
+
+# Compiler and linker options for application code and kernel code. These
+# options ensure that the compiler has the correct settings for the selected
+# instruction set and interworking.
+ARM_INTERWORK_M_OPT = "${@['-mno-thumb-interwork', '-mthumb-interwork'][bb.data.getVar('THUMB_INTERWORK', d, 1) == 'yes']}"
+ARM_THUMB_M_OPT = "${@['-mno-thumb', '-mthumb'][bb.data.getVar('ARM_INSTRUCTION_SET', d, 1) == 'thumb']}"
+
+#
+TARGET_CC_ARCH += "${ARM_INTERWORK_M_OPT} ${ARM_THUMB_M_OPT}"
+TARGET_CC_KERNEL_ARCH += "-mno-thumb-interwork -mno-thumb"
+