Linux – Determine target ISA extensions of binary file in Linux (library or executable)

cpu-architectureexecutableinstruction-setlinuxshared-libraries

We have an issue related to a Java application running under a (rather old) FC3 on an Advantech POS board with a Via C3 processor. The java application has several compiled shared libs that are accessed via JNI.

Via C3 processor is supposed to be i686 compatible. Some time ago after installing Ubuntu 6.10 on a MiniItx board with the same processor, I found out that the previous statement is not 100% true. The Ubuntu kernel hanged on startup due to the lack of some specific and optional instructions of the i686 set in the C3 processor. These instructions missing in C3 implementation of i686 set are used by default by GCC compiler when using i686 optimizations. The solution, in this case, was to go with an i386 compiled version of Ubuntu distribution.

The base problem with the Java application is that the FC3 distribution was installed on the HD by cloning from an image of the HD of another PC, this time an Intel P4. Afterwards, the distribution needed some hacking to have it running such as replacing some packages (such as the kernel one) with the i386 compiled version.

The problem is that after working for a while the system completely hangs without a trace. I am afraid that some i686 code is left somewhere in the system and could be executed randomly at any time (for example after recovering from suspend mode or something like that).

My question is:

  • Is there any tool or way to find out at what specific architecture extensions a binary file (executable or library) requires? file does not give enough information.

Best Solution

The unix.linux file command is great for this. It can generally detect the target architecture and operating system for a given binary (and has been maintained on and off since 1973. wow!)

Of course, if you're not running under unix/linux - you're a bit stuck. I'm currently trying to find a java based port that I can call at runtime.. but no such luck.

The unix file command gives information like this:

hex: ELF 32-bit LSB executable, ARM, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.4.17, not stripped

More detailed information about the details of the architecture are hinted at with the (unix) objdump -f <fileName> command which returns:

architecture: arm, flags 0x00000112:
EXEC_P, HAS_SYMS, D_PAGED
start address 0x0000876c

This executable was compiled by a gcc cross compiler (compiled on an i86 machine for the ARM processor as a target)