NDK12b：clang和gcc使用独立工具链和相同的构建脚本生成的不同ELF

Question

Our product contains multiple source packages. Some of the source packages are built using autotool/conf.

Based on what google said of switching to clang as a default compiler for the NDK starting with NDK-13, we went ahead with the switch in the *.mk files as well as in our env setup and build scripts. No make files where changed.

We were using NDK-10d which is old, so we switched to NDK-12b. We also generated a standalone toolchain from it, as recommended by Android's documentation, to simplify our build scripts and standardize across all.

The issue I am facing is the crash on launch as soon as the native code is loaded. What I have noticed is a warning in logcat regarding: unused DT entry: type 0x6ffffffe ( VERNEED ) and 0x6fffffff ( VERNEEDNUM ).

Then, the dreaded: A/libc: Fatal signal 11 (SIGSEGV), code 1, fault addr 0x30 in tid 22246 .

The stack trace tells me very, very little:

08-11 15:31:02.421 128-128/? I/DEBUG:     #00 pc 00036b8c  /system/lib/libc.so
08-11 15:31:02.421 128-128/? I/DEBUG:     #01 pc 0003817b  /system/lib/libc.so (vfprintf+18)
08-11 15:31:02.421 128-128/? I/DEBUG:     #02 pc 00035251  /system/lib/libc.so (fprintf+12)
08-11 15:31:02.421 128-128/? I/DEBUG:     #03 pc 000015fd  /data/app/com.myapp.demo-1/lib/arm/libappdebug.so (pipe_listen+328)
08-11 15:31:02.421 128-128/? I/DEBUG:     #04 pc 0001659b  /system/lib/libc.so
08-11 15:31:02.421 128-128/? I/DEBUG:     #05 pc 000144c3  /system/lib/libc.so

Notice that comparing the data within the ELFs as dumped by readelf -d shows the absence of those 2 DT entries in the binaries generated by arm-linux-androideabi-gcc-4.9 builds.

Any ideas, pointers, ...anything at all ..., would be much appreciated cuz i have been stuck for (blush) 3 days now.

Thanks.

Answer 1

You need to look into the problem of your unused DT entry . If you're using your library to pipe stuff somewhere else, that warning will appear at every run and endanger your pipe to receive garbage, or your app to receive excpetions. Please have a look at my post here .