minetest/doc/developing/misc.md

Miscellaneous

Sign the Android APK from CI

The Github Actions Workflow automatically produces an APK for each architecture. Before installing them onto a device they however need to be signed.

This requires an installation of the Android SDK and adb.

.../android-sdk/build-tools/30.0.3/apksigner sign --ks ~/.android/debug.keystore \
	app-arm64-v8a-release-unsigned.apk
# Enter 'android' (without quotes) when asked for a password

Note that the debug.keystore will not exist if you have never compiled an Android app on your system (probably).

After that installing it will work:

adb install -r -d ./app-arm64-v8a-release-unsigned.apk

How to get debug output from Minetest on Android

In case debug.txt isn't enough (e.g. when debugging a crash), you can get debug output using logcat:

adb logcat -s 'Minetest:*' '*:F'

Note that you can do this even after the app has crashed, since Android keeps an internal buffer.

A segmentation fault for example looks like this:

01-10 17:20:22.215 19308 20560 F libc    : Fatal signal 6 (SIGABRT), code -1 (SI_QUEUE) in tid 20560 (MinetestNativeT), pid 19308 (netest.minetest)
01-10 17:20:22.287 20576 20576 F DEBUG   : *** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
01-10 17:20:22.287 20576 20576 F DEBUG   : Build fingerprint: '...'
01-10 17:20:22.287 20576 20576 F DEBUG   : Revision: '4'
01-10 17:20:22.287 20576 20576 F DEBUG   : ABI: 'arm64'
01-10 17:20:22.288 20576 20576 F DEBUG   : Timestamp: 2024-01-10 17:20:22+0100
01-10 17:20:22.288 20576 20576 F DEBUG   : pid: 19308, tid: 20560, name: MinetestNativeT  >>> net.minetest.minetest <<<
01-10 17:20:22.288 20576 20576 F DEBUG   : uid: 10385
01-10 17:20:22.288 20576 20576 F DEBUG   : signal 6 (SIGABRT), code -1 (SI_QUEUE), fault addr --------
[ ... more information follows ... ]

Profiling Minetest on Linux

We will be using a tool called "perf", which you can get by installing perf or linux-perf or linux-tools-common.

For best results build Minetest and Irrlicht with debug symbols (-DCMAKE_BUILD_TYPE=RelWithDebInfo or -DCMAKE_BUILD_TYPE=Debug).

Run the client (or server) like this and do whatever you wanted to test:

perf record -z --call-graph dwarf -- ./bin/minetest

This will leave a file called "perf.data".

You can open this file with perf built-in tools but much more interesting is the visualization using a GUI tool: Hotspot. It will give you flamegraphs, per-thread, per-function views and much more.