cmd/go: Cross-compilation for android/arm fails on Linux, while other arm platforms succeed

[ChimeraCoder]

After updating to 1.4, I wanted to check out the sample Android applications. At first, go get golang.org/x/mobile/example/basic failed, as it couldn't find EGL/egl.h and GLES2/gl2.h (solution: install libgles2-mesa-dev and libegl1-mesa-dev, after which go get succeeds).

After installing these, I attempted to set up cross-compilation for the android/arm platform. For convenience, I used davecheney's helper script (it does not include android/arm, so I added it manually). Using this script, I am able to build Go for all the platforms except android/arm, which gives the following error:

gcc: error: unrecognized command line option ‘-marm’

However, freebsd/arm and linux/arm succeed with no such issue. (Attempting to compile the sample Android application fails with the same error message, for what it's worth).

I initially thought this was an issue with Debian (Wheezy) packages being out of date, but I run into the same issues on Arch as well (both machines are x86_64, and both have the Android SDK installed).

[adg]

@davecheney @crawshaw

[davecheney]

One of two things is happening.

1. My old cross compile scripts explicitly disable cgo, which is required for the android/arm port
2. You haven't supplied the correct CC variables to point to a version of gcc that can produce arm code.

I don't think using my cross compile scripts to produce an android development environment will be successful.

On 22 Dec 2014, at 12:23, Aditya Mukerjee notifications@github.com wrote:

After updating to 1.4, I wanted to check out the sample Android applications. At first, go get golang.org/x/mobile/example/basic failed, as it couldn't find EGL/egl.h and GLES2/gl2.h (solution: install libgles2-mesa-dev and libegl1-mesa-dev, after which go get succeeds).

After installing these, I attempted to set up cross-compilation for the android/arm platform. For convenience, I used davecheney's helper script (it does not include android/arm, so I added it manually). Using this script, I am able to build Go for all the platforms except android/arm, which gives the following error:

gcc: error: unrecognized command line option ‘-marm’

However, freebsd/arm and linux/arm succeed with no such issue. (Attempting to compile the sample Android application fails with the same error message, for what it's worth).

I initially thought this was an issue with Debian (Wheezy) packages being out of date, but I run into the same issues on Arch as well (both machines are x86_64, and both have the Android SDK installed).

—
Reply to this email directly or view it on GitHub.

[bryanturley]

I have this in my notes, it may help you.
Your CC_FOR_TARGET may be different, it should be the ndk's gcc.

CC_FOR_TARGET=arm-linux-androideabi-gcc GOOS=android GOARCH=arm GOARM=7 ./make.bash
That is the make.bash in go/src/ and a "standalone toolchain" read the ndk docs for that bit.

[davecheney]

Don't forget the --no-clean on the end.

On 22 Dec 2014, at 12:51, Bryan Turley notifications@github.com wrote:

I have this in my notes, it may help you.
Your CC_FOR_TARGET may be different, it should be the ndk's gcc.

CC_FOR_TARGET=arm-linux-androideabi-gcc GOOS=android GOARCH=arm GOARM=7 ./make.bash
That is the make.bash in go/src/ and a "standalone toolchain" read the ndk docs for that bit.

—
Reply to this email directly or view it on GitHub.

[ChimeraCoder]

Success! Here's what I had to do:

1. Reinstall the NDK toolchain (perhaps it was stale before):
   ./android-ndk-r10c/build/tools/make-standalone-toolchain.sh --platform=android-21 --install-dir=$NDK_ROOT
2. CC_FOR_TARGET was indeed the key missing environment variable.

CC_FOR_TARGET="$NDK_ROOT/toolchain/arm-linux-androideabi/bin/gcc" GOOS=android GOARCH=arm GOARM=7 ./make.bash

1. Edit make.bash in the project directory (not the one in /usr/local/go/src) to use the full path to ndk-build. (I think there is a $PATH issue here: while ndk-build is in the $PATH, if I didn't use the absolute path, it wouldn't look in the right directory for a number of .so files.)

After that, it was able to build ./bin/nativeactivity-debug.apk, which I've confirmed runs on my phone.

Thanks!

[ChimeraCoder]

Oh, and for posterity - this was on the machine running Arch, as Wheezy doesn't have glibc 2.14, which the NDK requires.

[davecheney]

Don't forget --no - clean, otherwise you will end up with a go install that
can only build for android/arm
On 22 Dec 2014 16:17, "Aditya Mukerjee" notifications@github.com wrote:

Oh, and for posterity - this was on the machine running Arch, as Wheezy
doesn't have glibc 2.14, which the NDK requires.

—
Reply to this email directly or view it on GitHub
#9412 (comment).

[chidea]

Was able to do the same with go1.6 with CC=<stand-alone-toolchain>/bin/arm-linux-androideabi-gcc and CXX=<stand-alone-toolchain>/bin/arm-linux-androideabi-g++ on android ndk r10e.

It's also available on windows with .exe attached to them and using make.bat instead of .bash.
Full command with powershell was like bellow when <stand-alone-toolchain>/bin/ was added to path environment variable.

$env:CC="arm-linux-androideabi-gcc.exe";$env:CXX="arm-linux-androideabi-g++.exe" ; $env:GOOS='android'; $env:GOARCH='arm'; $env:GOARM=7; $env:CGO_ENABLED=1; ./make.bat --no-clean