Trevor Robinson created HADOOP-8659:
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             Summary: Native libraries must build with soft-float ABI for 
Oracle JVM
                 Key: HADOOP-8659
                 URL: https://issues.apache.org/jira/browse/HADOOP-8659
             Project: Hadoop Common
          Issue Type: Bug
          Components: native
         Environment: armhf Linux with Oracle JVM
            Reporter: Trevor Robinson
            Assignee: Trevor Robinson


There was recently an ABI (application binary interface) change in most Linux 
distributions for modern ARM processors (ARMv7). Historically, hardware 
floating-point (FP) support was optional/vendor-specific for ARM processors, so 
for software compatibility, the default ABI required that processors with FP 
units copy FP arguments into integer registers (or memory) when calling a 
shared library function. Now that hardware floating-point has been standardized 
for some time, Linux distributions such as Ubuntu 12.04 have changed the 
default ABI to leave FP arguments in FP registers, since this can significantly 
improve performance for FP libraries.

Unfortunately, Oracle has not yet released a JVM (as of 7u4) that supports the 
new ABI, presumably since this involves some non-trivial changes to components 
like JNI. While the soft-float JVM can run on systems with multi-arch support 
(currently Debian/Ubuntu) using compatibility libraries, this configuration 
requires that any third-party JNI libraries also be compiled using the 
soft-float ABI. Since hard-float systems default to compiling for hard-float, 
an extra argument to GCC (and installation of a compatibility library) is 
required to build soft-float Hadoop native libraries that work with the Oracle 
JVM.

Note that OpenJDK on hard-float systems does use the new ABI, and expects JNI 
libraries to use it as well. Therefore the fix for this issue requires 
detecting the float ABI of the current JVM.

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