Peter A. Bigot : gcc: update compiler architecture to match gcc-runtime ( armv6, armv7a)

Module: openembedded-core.git
Branch: master-next
Commit: 0ba6ab39f187ecd4261f08e768f365f461384a3a
URL:    http://git.openembedded.org/?p=openembedded-core.git&a=commit;h=0ba6ab39f187ecd4261f08e768f365f461384a3a

Author: Peter A. Bigot <[email protected]>
Date:   Thu Aug 14 14:05:59 2014 -0500

gcc: update compiler architecture to match gcc-runtime (armv6, armv7a)

The gcc-runtime recipe builds the gcc libraries including libstdc++ with $TARGET_CC_ARCH flags, which include -march=FOO flags that affect whether atomic instructions are available. This causes an ABI incompatibility when the compiler by default generates code for less capable architectures. For example, gcc-runtime libraries on a Cortex-A8 are built with a different C++11/C++14 mutex implementation than is used code compiled outside OE and without architecture-specific flags.

This commit fixes the problem specifically for ABI issues related to atomic instructions available in ARMV6 and subsequent architectures. Other ABI incompatibilities may remain in other architectures.

See: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62100

Signed-off-by Peter A. Bigot <[email protected]>

Signed-off-by Richard Purdie <[email protected]>

---

  meta/recipes-devtools/gcc/gcc-configure-common.inc | 7 +++++++
  1 file changed, 7 insertions(+)

meta/recipes-devtools/gcc/gcc-configure-common.inc +7 -0

index 71dce12..48fb799 100644
@@ -64,6 +64,13 @@ EXTRA_OECONF_append_libc-uclibc = " --enable-__cxa_atexit"
  EXTRA_OECONF_append_mips64 = " --with-abi=64 --with-arch-64=mips64 --with-tune-64=mips64"
  EXTRA_OECONF_append_mips64el = " --with-abi=64 --with-arch-64=mips64 --with-tune-64=mips64"
 
+# ARMv6+ adds atomic instructions that affect the ABI in libraries built
+# with TUNE_CCARGS in gcc-runtime.  Make the compiler default to a
+# compatible architecture.  armv6 and armv7a cover the minimum tune
+# features used in OE.
+EXTRA_OECONF_append_armv6 = " --with-arch=armv6"
+EXTRA_OECONF_append_armv7a = " --with-arch=armv7-a"
+
  EXTRA_OECONF_GCC_FLOAT ??= ""
  CPPFLAGS = ""
 

Hi Peter,

The commit caused building gcc-crosssdk-initial-x86_64 failed.
...
Unknown CPU given in --with-arch=armv7-a.
...

While crosssdk, TARGET_ARCH = "${SDK_ARCH}" (set in crosssdk.bbclass) so the values of '--target=x86_64-wrlinuxsdk-linux --with-arch=armv7-a' triggered the above failure.

How about override for the 'target/cross' and not for 'crosssdk' ?

Quoted 7 lines · Hongxu Jia

Hi Peter,

The commit caused building gcc-crosssdk-initial-x86_64 failed.
...
Unknown CPU given in --with-arch=armv7-a.
...

Quoted 5 lines

While crosssdk, TARGET_ARCH = "${SDK_ARCH}" (set in crosssdk.bbclass) so the values of '--target=x86_64-wrlinuxsdk-linux --with-arch=armv7-a' triggered the above failure.

How about override for the 'target/cross' and not for 'crosssdk' ?

This was fixed with:

http://git.yoctoproject.org/cgit.cgi/poky/commit/?id=7095d8da4b3e1a6bc475f1cb5e6d7fedb2a76901

Cheers,

Richard