http://www.cnblogs.com/q191201771/p/3875316.html
root@socfpga:/media/ram/nfs/dvb# ./a.out ./a.out: /lib/libc.so.6: version `GLIBC_2.17' not found (required by ./a.out)
root@socfpga:/media/ram/nfs/dvb# strings /lib/libc.so.6 | grep GLIBC GLIBC_2.4 GLIBC_2.5 GLIBC_2.6 GLIBC_2.7 GLIBC_2.8 GLIBC_2.9 GLIBC_2.10 GLIBC_2.11 GLIBC_2.12 GLIBC_2.13 GLIBC_2.14 GLIBC_2.15 GLIBC_PRIVATE GNU C Library (Ubuntu EGLIBC 2.15-0ubuntu10) stable release version 2.15, by Roland McGrath et al.
root@iZ25uck2l28Z:/tmp/tmp# nm a.out | grep GLIBC_2.17 U clock_gettime@@GLIBC_2.17
发现是clock_gettime有问题
@ man clock_gettime，可以看到其中有一句话 Link with -lrt (only for glibc versions before 2.17).
所以在编译a.out时添加-lrt即可