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authorYann E. MORIN <yann.morin.1998@anciens.enib.fr>2011-01-09 01:45:09 +0100
committerKhem Raj <raj.khem@gmail.com>2011-06-11 00:12:22 -0700
commit7a246fda8e3bd2067d44e01c30c8ce761dad39a8 (patch)
treedfff27e27af92783d8f81176ad24717e4fbdf0d2
parent3862c65a05983b2b18cb7884a124a905828f7a18 (diff)
ARM: detect BX availibility at build time
The "use BX" option is now a suggestion that BX be used if available. Use a macro to detect if BX is available at build time. If so, and the user requested it be used, then use it. Otherwise, error out. Macro courtesy Khem RAJ: http://lists.uclibc.org/pipermail/uclibc/2009-April/042301.html Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr> Cc: Khem Raj <raj.khem@gmail.com> Cc: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com> Cc: Carmelo AMOROSO <carmelo.amoroso@st.com> Signed-off-by: Khem Raj <raj.khem@gmail.com>
-rw-r--r--extra/Configs/Config.arm4
-rw-r--r--libc/sysdeps/linux/arm/bits/arm_asm.h9
2 files changed, 11 insertions, 2 deletions
diff --git a/extra/Configs/Config.arm b/extra/Configs/Config.arm
index 4ab7da0d1..0bb2971a9 100644
--- a/extra/Configs/Config.arm
+++ b/extra/Configs/Config.arm
@@ -33,4 +33,6 @@ config COMPILE_IN_THUMB_MODE
config USE_BX
bool "Use BX in function return"
help
- Use BX instruction for THUMB aware architectures.
+ Say 'y' to use BX to return from functions on your thumb-aware
+ processor. Say 'y' if you need to use interworking. Say 'n' if not.
+ It is safe to say 'y' even if you're not doing interworking.
diff --git a/libc/sysdeps/linux/arm/bits/arm_asm.h b/libc/sysdeps/linux/arm/bits/arm_asm.h
index 1d87df6eb..921c9a3c9 100644
--- a/libc/sysdeps/linux/arm/bits/arm_asm.h
+++ b/libc/sysdeps/linux/arm/bits/arm_asm.h
@@ -24,5 +24,12 @@
#define THUMB1_ONLY 1
#endif
-#endif /* _ARM_ASM_H */
+#if defined(__USE_BX__)
+# if ( defined (__ARM_ARCH_2__) || defined (__ARM_ARCH_3__) \
+ || defined (__ARM_ARCH_3M__) || defined (__ARM_ARCH_4__) \
+ )
+# error Use of BX was requested, but is not available on the target processor.
+# endif /* ARCH level */
+#endif /* __USE_BX__ */
+#endif /* _ARM_ASM_H */