[fweimer]

GNU/Linux applications are typically quite portable across CPUs. Is Android really that different? I would expect that once you have ported it an NDK application to at least two architectures, the third one should be really easy. And with Android, you already get two easily testable architecture (the ubiquitous aarch64, and x86-64 under virtualization).

(It's not that many Debian or Fedora community contributors have a mainframe in their basement—yet the software they package tends to build and run on s390x just fine. Okay, maybe there are some endianess issues, but you wouldn't hit those with RISC-V.)

[charcircuit]

Assuming you have the source code for all your native code, then yes it should mostly work. 3rd party libraries can contain native code which means that you may be dependent on someone else porting their code.

[dathinab]

> Is Android really that different?

no, this has little to do with android

but "GNU/Linux applications are typically quite portable across CPUs" is only this case because a lot of people have a lot of interest and time invested into making that work

but for many commercial apps there is little insensitive to spend any time into making them work with anything but ARM (even older armv7 might not be supported because depending on what your app does the market share makes that not worth it)

still with both ARM and RSIV-V havine somewhat similar memory models and in general today people writing much more C/C++ standard compatible code instead of "it's UB in therefor but will work on this hardware"-nonsense I don't see to many technical issues

on issue could be that a non negligible amount of Android apps which use the NDK use it only to "link" code from other toolchains into android apps, e.g. rust binaries. And while I'm not worried about rust I wouldn't be surprised if some toolchains used might not support RISK-V when it starts to become relevant. Especially when it comes to the (mostly but not fully) snake oil nonsense stuff banking apps tend to use I would be surprised if there wouldn't be some issues.

Through in the end the biggest issue is a fully non technical one:

- if you release an app with NDK you want to test it on real hardware for all archs you support (no matter if there is some auto cross compilation or interpretation (like Roseta)

- but to do so you need access to such hardware, emulators might be okay but are not always cutting it

- but there aren't any RISK-V android phones yet

- but to release such phones you want to have apps, especially stuff like paypal or banking apps available

- but to have such things available the providers much evaluate it to be worth the money it costs to test which is based on marked share which is starting at 0 and slow growing due to missing support for some apps and missing killer features

So I think RISK-V android will be a think but as long as multiple big companies are not pushing it strongly it will take a very long time until it becomes relevant in any way.