Difference between armeabi and armeabi-v7a

Question

As far as I can tell from the docs, the difference between the two supported flavors of ARM architecture in Android NDK is only in the set of supported CPU instructions. Is that really so? Is there no difference in calling conventions, or system call sequence, or something else?

I'm wondering what will happen if I compile a module to an ARM object file (with a compiler other than NDK - Free Pascal specifically), specifying ARMv6 as the architecture, and then link it to both armeabi and armeabi-v7a shared libraries. The FPC bits are not supposed to perform neither system calls nor Java calls, except via my own C-based interface.

EDIT: a hello world library, compiled with FPC for ARM, links and runs under ARMv7a emulator.

"I'm wondering what will happen" You could try :) No idea if that works, but the Internet suggests that there are ways to get Free Pascal code to run on Android. — zapl
Things like subtle EABI mismatches typically manifest on edge cases, as opposed to blowing up in your face right away. And performing coverage testing aiming for 100% is not something I'd undertake willy-nilly. — Seva Alekseyev

Alex Cohn Alex Cohn · Accepted Answer · 2012-09-02T09:32:23

You definitely can run armeabi shared library on v7, and you can call its exported functions from another module. So, to be on the safe side, I would create a separate .so file from you Pascal code, sticking to armeabi (maybe with some C/C++ wrappers), and use this shared library with both your armeabi and armeabi-v7a libraries. The easiest way to load everything in correct order is to use

System.loadLibrary("pascal"); // armeabi
System.loadLibrary("c++"); // the platform will choose armeabi or armeabi-v7a

Difference between armeabi and armeabi-v7a

1 Answers