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memo -- trouble shooting for Fenix build (Apple M4 Pro chip)

February 24, 2025
Table of Contents
docs for build Fenix
summary (not 100% guaranteed)
log
Fenix is Firefox for android. It's different from ordinary Firefox in many ways.
 docs for build Fenixhttps://firefox-source-docs.mozilla.org/mobile/android/index.html

https://firefox-source-docs.mozilla.org/mobile/android/fenix.html
 summary (not 100% guaranteed)I'd already built Firefox on bookmarks/central.
I followed the doc.
Ran softwareupdate --install-rosetta.
Ran ./mach --no-interactive bootstrap --application-choice="GeckoView/Firefox for Android".

Then I have to set $JAVA_HOME and $ANDROID_HOMEas this doc says.export JAVA_HOME=$HOME/.mozbuild/jdk/jdk-<latest-version>/Contents/Home
export ANDROID_HOME=$HOME/.mozbuild/android-sdk-<os_name>
You may possibly have to set $CPPFLAGS as empty when it fails.
I think those who installed jdk via homebrew might have to be careful about if switching jdk by $JAVA_HOME really works.
Usually osx can switch jdk version by changing $JAVA_HOME thanks to /usr/libexec/java_home.
But if your $PATH includes /opt/homebrew/opt/openjdk/bin, that may disable the switching.
I removed /opt/homebrew/opt/openjdk/bin from $PATH and confirmed this had enabled the switching.

Now run java --version. If your terminal answers OpenJDK Runtime Environment Temurin-17.0.14+7 (build 17.0.14+7), let's build by ./mach build. That's it.
 logI use Mac with an Apple M4 Pro chip.
I followed the doc: https://firefox-source-docs.mozilla.org/mobile/android/index.html#id1
I'd already built Firefox on bookmarks/central.
So started from running softwareupdate --install-rosetta. It succeeded.
Ran ./mach --no-interactive bootstrap --application-choice="GeckoView/Firefox for Android". It succeeded.
Then, ./mach build caused an error. So installed Android Studio for the moment. But ./mach build still caused an error.$ ./mach build
.........
0:01.76 security/nss/lib/pki
0:01.81 security/nss/lib/smime
0:02.13 /Users/XXXXXX/mozilla-unified/mozglue/android/APKOpen.cpp:114:44: error: cannot initialize a parameter of type 'void **' with an rvalue of type 'JNIEnv **' (aka 'JNIEnv_ **')
0:02.13   114 |       sJavaVM->AttachCurrentThreadAsDaemon(&env, nullptr) != JNI_OK) {
0:02.13       |                                            ^~~~
0:02.13 /opt/homebrew/opt/openjdk/include/jni.h:1959:45: note: passing argument to parameter 'penv' here
0:02.13  1959 |     jint AttachCurrentThreadAsDaemon(void **penv, void *args) {
0:02.13       |                                             ^
0:02.24 1 error generated.
0:02.25 make[4]: *** [APKOpen.o] Error 1
0:02.25 make[3]: *** [mozglue/android/target-objects] Error 2
0:02.25 make[3]: *** Waiting for unfinished jobs....
0:03.52 make[2]: *** [compile] Error 2
0:03.52 make[1]: *** [default] Error 2
0:03.52 make: *** [build] Error 2
0:03.62 W 82 compiler warnings present.
The error message implied version-mismatch. Checked the current default java location and version.$ java --version
openjdk 23.0.2 2025-01-21
OpenJDK Runtime Environment Homebrew (build 23.0.2)
OpenJDK 64-Bit Server VM Homebrew (build 23.0.2, mixed mode, sharing)

$ which java
/opt/homebrew/opt/openjdk/bin/java
Confirmed that Android Studio used the jbr runtime for Gradle. This runtime had another version.$ /Applications/Android\ Studio.app/Contents/jbr/Contents/Home/bin/java --version
openjdk 21.0.4 2024-07-16
OpenJDK Runtime Environment (build 21.0.4+-12422083-b607.1)
OpenJDK 64-Bit Server VM (build 21.0.4+-12422083-b607.1, mixed mode)
Seemed like better to use the jbr one. idk. Anyway set it to the fenix build setting.(ref: https://firefox-source-docs.mozilla.org/mobile/android/fenix.html#building-firefox-for-android)$ export JAVA_HOME=/Applications/Android\ Studio.app/Contents/jbr/Contents/Home
$ printenv JAVA_HOME
/Applications/Android Studio.app/Contents/jbr/Contents/Home
Tried again. But the same.$ ./mach clobber # reset build
$ ./mach build
# same error
Searching bugzilla, found the issue about JDK version: https://bugzilla.mozilla.org/show_bug.cgi?id=1785929
Installed JDK 17 and set it to the setting. Same error.$ brew install openjdk@17
$ /opt/homebrew/opt/openjdk@17/bin/java --version
openjdk 17.0.14 2025-01-21
OpenJDK Runtime Environment Homebrew (build 17.0.14+0)
OpenJDK 64-Bit Server VM Homebrew (build 17.0.14+0, mixed mode, sharing)
$ export JAVA_HOME=/opt/homebrew/opt/openjdk@17
$ printenv JAVA_HOME
/opt/homebrew/opt/openjdk@17
$ ./mach clobber # reset build
$ ./mach build
........
0:02.01 /Users/XXXXXX/mozilla-unified/mozglue/android/APKOpen.cpp:114:44: error: cannot initialize a parameter of type 'void **' with an rvalue of type 'JNIEnv **' (aka 'JNIEnv_ **')
0:02.01   114 |       sJavaVM->AttachCurrentThreadAsDaemon(&env, nullptr) != JNI_OK) {
0:02.01       |                                            ^~~~
0:02.01 /opt/homebrew/opt/openjdk/include/jni.h:1959:45: note: passing argument to parameter 'penv' here
0:02.01  1959 |     jint AttachCurrentThreadAsDaemon(void **penv, void *args) {
0:02.01       |                                             ^
0:02.16 1 error generated.
0:02.17 make[4]: *** [APKOpen.o] Error 1
0:02.17 make[3]: *** [mozglue/android/target-objects] Error 2
0:02.17 make[3]: *** Waiting for unfinished jobs....
0:03.31 make[2]: *** [compile] Error 2
0:03.31 make[1]: *** [default] Error 2
0:03.31 make: *** [build] Error 2
0:03.42 W 82 compiler warnings present.
The error said 0:02.01 /opt/homebrew/opt/openjdk/include/jni.h:1959:45: note: passing argument to parameter 'penv' here. Clearly the version was not switched.
To switch JDK versions, OSX uses /usr/libexec/java_home but my mac can't perform it. Google told me I had to set a symbolic link if I installed jdk by homebrew: https://formulae.brew.sh/formula/openjdk$ /usr/libexec/java_home -V
The operation couldn’t be completed. Unable to locate a Java Runtime.
Please visit http://www.java.com for information on installing Java.
$ sudo ln -sfn $(brew --prefix)/opt/openjdk/libexec/openjdk.jdk /Library/Java/JavaVirtualMachines/openjdk.jdk
$ /usr/libexec/java_home -V
Matching Java Virtual Machines (1):
    23.0.2 (arm64) "Homebrew" - "OpenJDK 23.0.2" /opt/homebrew/Cellar/openjdk/23.0.2/libexec/openjdk.jdk/Contents/Home
/opt/homebrew/Cellar/openjdk/23.0.2/libexec/openjdk.jdk/Contents/Home
Added 17, too. (idk i should've added jbr also.)# you have to add "-17" at last!
# https://engineering.mobalab.net/2022/06/06/how-to-install-java-on-macos-in-2022/
$ sudo ln -sfn $(brew --prefix)/opt/openjdk@17/libexec/openjdk.jdk /Library/Java/JavaVirtualMachines/openjdk-17.jdk
$ /usr/libexec/java_home -V
Matching Java Virtual Machines (2):
    23.0.2 (arm64) "Homebrew" - "OpenJDK 23.0.2" /opt/homebrew/Cellar/openjdk/23.0.2/libexec/openjdk.jdk/Contents/Home
    17.0.14 (arm64) "Homebrew" - "OpenJDK 17.0.14" /opt/homebrew/Cellar/openjdk@17/17.0.14/libexec/openjdk.jdk/Contents/Home
/opt/homebrew/Cellar/openjdk/23.0.2/libexec/openjdk.jdk/Contents/Home
But switching doesn't succeed. PATH was not set appropriately. Specifically, export PATH="/opt/homebrew/opt/openjdk/bin:$PATH" was a problem. This prenveted switching. So commented it out and wrote aliases.// .zshrc //
# comment out these two.
# export PATH="/opt/homebrew/opt/openjdk/bin:$PATH"
# export CPPFLAGS="-I/opt/homebrew/opt/openjdk/include"
alias setjdk17='export JAVA_HOME=$(/usr/libexec/java_home -v 17.0.14); export CPPFLAGS="-I$JAVA_HOME/include"'
alias setjdk23='export JAVA_HOME=$(/usr/libexec/java_home -v 23.0.2); export CPPFLAGS="-I$JAVA_HOME/include"'
Now switching worked.$ java --version
openjdk 23.0.2 2025-01-21
OpenJDK Runtime Environment Homebrew (build 23.0.2)
OpenJDK 64-Bit Server VM Homebrew (build 23.0.2, mixed mode, sharing)
$ setjdk17
$ java --version
openjdk 17.0.14 2025-01-21
OpenJDK Runtime Environment Homebrew (build 17.0.14+0)
OpenJDK 64-Bit Server VM Homebrew (build 17.0.14+0, mixed mode, sharing)
$ echo $CPPFLAGS
-I/opt/homebrew/Cellar/openjdk@17/17.0.14/libexec/openjdk.jdk/Contents/Home/include
$ setjdk23
$ java --version
openjdk 23.0.2 2025-01-21
OpenJDK Runtime Environment Homebrew (build 23.0.2)
OpenJDK 64-Bit Server VM Homebrew (build 23.0.2, mixed mode, sharing)
$ echo $CPPFLAGS
-I/opt/homebrew/Cellar/openjdk/23.0.2/libexec/openjdk.jdk/Contents/Home/include
Finally, built Fenix with jdk17. But it caused another error.$ ./mach clobber
$ setjdk17
$ java --version
openjdk 17.0.14 2025-01-21
OpenJDK Runtime Environment Homebrew (build 17.0.14+0)
OpenJDK 64-Bit Server VM Homebrew (build 17.0.14+0, mixed mode, sharing)
$ ./mach build
...bluh bluh... /opt/homebrew/Cellar/openjdk@17/17.0.14/libexec/openjdk.jdk/Contents/Home/include/jni.h:45:10: fatal error: 'jni_md.h' file not found
I set CPPFLAGS back to /opt/homebrew/opt/openjdk/include. But it caused the error, again.
Finally, I tried the below. And under these settings, the build succeeded!$ echo $JAVA_HOME
/Users/XXXXXX/.mozbuild/jdk/jdk-17.0.14+7/Contents/Home
$ echo $ANDROID_HOME
/Users/XXXXXX/.mozbuild/android-sdk-macosx
$ echo $CPPFLAGS

$ java --version
openjdk 17.0.14 2025-01-21
OpenJDK Runtime Environment Temurin-17.0.14+7 (build 17.0.14+7)
OpenJDK 64-Bit Server VM Temurin-17.0.14+7 (build 17.0.14+7, mixed mode, sharing)
$ cat mozconfig
# Build GeckoView/Firefox for Android:
ac_add_options --enable-project=mobile/android
# If --target is not specified it will default to host architecture for fast
# emulation (x86_64 or aarch64). For testing on physical phones you most likely
# want to use an aarch64 (ARM64) target.
# ac_add_options --target=aarch64
$ ./mach build
$ ./mach run --app=fenix

FYI, you don't have to ./mach build unless you change C++ code. Changes for Java and Kotlin code for Firefox Android will be reflected by ./mach run --app=fenix.
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