CODEWITHSUNDEEP
androidc++android-ndk
James Feng
James Feng

Reputation: 314

Should I rebuild all libs when I upgrade the NDK version?

There's many shared libs(*.so) in my android project. Some of them were built by others, I don't have the source code.

I'm using NDK r10e, and I want to upgrade the NDK version to r13b.

If I don't change the makefile, just build part of the shared libs with NDK-r13b, others built with NDK-r10e were not changed. Is there any problem with capability of the android program? 

NDK-r10e use clang-3.5
NDK-r13b use clang-3.8

following configurations are the same:

APP_ABI := armeabi-v7a
APP_PLATFORM := android-19
APP_STL := gnustl_shared

Upvotes: 3

Views: 225

Answers (1)

Dan Albert
Dan Albert

Reputation: 10509

It's generally a good idea, but isn't always required. We try to preserve compatibility across NDK versions since, yes, moving across a compatibility boundary is difficult when you don't have the source to your dependencies, but sometimes bugs can't be fixed without breaking compatibility.

It's generally a good idea because doing so will have the least surprises. We only ever test a version of the NDK against itself. It will also save you a lot of time trying to figure what went wrong when there are compatibility breaks.

A couple examples (by no means a complete list) of things that can go wrong:

The public API surface of the NDK has changed over time. The APIs still exist on the device so that legacy apps continue working, but sometimes APIs are removed from the NDK so that new apps don't use them (there are a handful of reasons this might happen). In these cases, an old library that uses a removed symbol won't be able to be linked against a new library/executable using an NDK that doesn't have those APIs (this actually depends on the behavior of the linker; it's always true for static libraries, I think it's only arm64 for shared libraries).

For upgrading from r10 in particular, there was an ABI break in libc++ (required to avoid nasty interactions with the system) that means that libraries built with r10 and libraries built with r11+ are not compatible. You're using gnustl, so that problem won't affect you, but it's worth mentioning for others that land here.

Upvotes: 3

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