1462936 - "mach android-emulator" with x86-6.0 and x86-7.0 does not work on macOS

Status: RESOLVED FIXED

(Firefox for Android Graveyard :: Testing, defect)

Description

[Rob Wu [:robwu]]

I ran "mach bootstrap" and selected Android, artifact mode. Then I modified the suggested mozconfig to target x86 (similar to the one at https://developer.mozilla.org/en-US/docs/Mozilla/Developer_guide/Build_Instructions/Simple_Firefox_for_Android_build):
ac_add_options --target=i386-linux-android

Upon running the following commands, I expected a working emulator:
mach android-emulator --version=x86
mach android-emulator --version=x86-6.0
mach android-emulator --version=x86-7.0

x86 starts (though "mach install" causes a segfault and the Android OS reboots. xpcshell tests run successfully.


x86-6.0 and x86-7.0 fails, however. The emulator's UI appears (but with black screen), and the launcher icon on my dock (macOS) has the icon of a folder instead of the emulator.

I debugged a lot and found a way to get around this (I'll attach a patch).

After applying my patch, the emulator can be launched via "mach android-emulator".



There are some other issues (below), but not blocking the workflow on macOS, so I'll just mention it for completeness.

- x86-6.0: Upon boot, "Unfortunately, Launcher3 has stopped" appears. I can dismiss (or ignore) the notification and run Firefox or tests as expected.

- x86-6.0 and x86-7.0: When the emulator starts, the following warning is shown:
> Cold boot: selected renderer 'swiftshader' doesn't support snapshots.
I did not experience any other obvious problems related to this. The renderer is set via the "-gpu swiftshader" option. The "swiftshader" options is also deprecated, by the way: https://developer.android.com/studio/run/emulator-acceleration#accel-graphics

- x86-6.0 and x86-7.0: "mach run" starts Firefox without issues. (yay)

- x86-6.0 and x86-7.0: "mach test path/to/xpcshell/tests" fails with SEGV, likely bug 1451930.


Test environment:
- macOS High Sierra (10.13.4)
- Freshly installed build tools via "mach bootstrap" and Firefox for Android, artifact builds.
- Android emulator version 27.2.9.0 (build_id 4773671) (CL:18fc969f023e3b369b34b08db237dd9addfe100a)
- Firefox source checked out on 18 May 2018.

Comment 1

[Rob Wu [:robwu]]

Attachment: Bug 1462936 - Use QEMU 2 engine for android-emulator for x86-6.0 and x86-7.0

Before this patch, the x86-6.0 and x86-7.0 Android emulators were
unusable on macOS (tested 10.13.4 High Sierra).
The emulator's UI appears (but with black screen), and the launcher
icon in the dock has a default folder icon instead of the emulator.

When I use "mach android-emulator --version=x86-6.0 --verbose",
then the full emulator command is printed. I discovered that
using the newer QEMU 2 engine ("-engine qemu2") fixes the issue, and
that the emulator launches as expected. This option is documented at:
https://developer.android.com/studio/run/emulator-commandline

However, when I modify the source of these commands, then the emulator
fails to start (as before). This is caused by the setpgid call via
preexec_fn in testing/mozbase/mozprocess/mozprocess/processhandler.py .
Passing ignore_children=True to ProcessHandler avoids the setpgid call
and allows the emulator to be used as expected on macOS.

The effect of not using setpgid is that the spawned process will not
be put in the process group of the "mach" Python script. This is not
a big deal. I can confirm that the emulator can still be killed by
quitting or force-quitting it, and did not experience other issues.

Review commit: https://reviewboard.mozilla.org/r/245320/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/245320/

Comment 2

[Geoff Brown [:gbrown]]

Comment on attachment 8979057 [details]
Bug 1462936 - Use QEMU 2 engine for android-emulator for x86-6.0 and x86-7.0

https://reviewboard.mozilla.org/r/245320/#review251254

Thanks for this Rob. I don't have a macOS environment and wasn't aware of this issue. I verified your patch on Ubuntu 16.4 -- all's well.

I'll just mention 2 small concerns:
 - I'm sure I tried -engine qemu2 on ubuntu 16.4 a few months ago and found that Android would not boot.
 - https://developer.android.com/studio/run/emulator-commandline says:

Specify the emulator engine:

    auto - Automatically select an engine (default).
    classic - Use the older QEMU 1 engine.
    qemu2 - Use the newer QEMU 2 engine.

For example:

$ emulator @Nexus_5X_API_23 -engine auto

Auto-detection should choose the value that provides the best performance when emulating a particular AVD. You should use the -engine option for debugging and comparison purposes only.

...but if we really need qemu2 on macOS, then we need it!

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/d2b91476bebc
Use QEMU 2 engine for android-emulator for x86-6.0 and x86-7.0 r=gbrown

Comment 4

[Arthur Iakab [arthur_iakab]]

https://hg.mozilla.org/mozilla-central/rev/d2b91476bebc