Develop Reference

Blank emulator after compililing Android 7.1.1 using Source code, how to get the emulator to work?

I have been trying to get the source code to compile from some time and finally got it compiled. However I am having issues with the emulator where it shows a pop up screen but is quite blank.
I am using Ubuntu Server Xenial and Android 7.1.1 for Nexus6P (but I dont own a Nexus6P so I need to run this on the emulator)
I have tried specifying all the directories such as (-sysdir,-sysdir, -datadir, -kernel, -ramdisk, -system, -data, -cache, -sdcard) although I know that these are supposed to be auto populated by the envsetup.sh file.
The command I used is this:
emulator -kernel ./prebuilts/qemu-kernel/arm64/kernel-qemu -ramdisk ./out/debug/target/product/angler/ramdisk.img -sysdir ./out/debug/target/product/angler/ -cache ./out/debug/target/product/angler/cache.img -system ./out/debug/target/product/angler/system.img -data ./out/debug/target/product/angler/userdata.img -memory 4096 -partition-size 4096 -sdcard sdcard.img -skindir ./sdk/emulator/skins/ -skin WVGA800
I changed the kernel to others such as for ARM/ARM64 but to no avail. All I see is a blank emulator and after changing it to ARM following error:
http://pastebin.com/A04NmNLn
I am at a loss as to why the emulator wont work. Also where is the "image" file with which we can install the Android on Genymotion-type external emulator.
Any help is appreciated!

In order to build AOSP to be run in emulator, there is no need to download any additional binaries. At the same time, emulator cannot run images build for real devices. Therefore, it is required to only download the sources of Android and execute the following commands within the directory with the downloaded sources:
source build/envsetup.sh
lunch aosp_arm-eng #or aosp_x86_64-eng, etc. for details see documentation
make -j4
After the sources are build in the same terminal run the emulator command and the emulator should appear.

Run custom ROM on Android Emulator

I downloaded a third-party ROM, and I want to run it on the emulator first before flash it into the phone. Here is the contents of cm-11-20140911-NIGHTLY-p3110.zip:
1. boot.img
2. file_contexts
3. META-INF/
4. recovery/
5. system/
I unpacked boot.img using the script unpack-bootimg.pl and get boot.img-kernel, and boot.img-ramdisk.cpio.gz. Then I repacked the system using the make_ext4fs and got system.img.
I created an AVD and execute:
emulator -system ~/cm11/system_new.img -ramdisk ~/cm11/boot.img-ramdisk.cpio.gz -kernel ~/cm11/boot.img-kernel -avd and442
but all I got is nothing, the emulator screen is just black. There is no log message from adb -s emulator-5554.
Now I am confused:
can the third-party ROM be tested by the emulator?
Am I doing the right way?

Yeah, why not.
We can flash a third-party ROM on Android AVD. But first you must know the following things:
1. The Android Emulator is itself a device, like your Moto G or Xperia
2. Every ROM is device-specific (supports a device-specific Kernel)
(on many sites/blogs you got information like you have to replace system.img file from .android\avd\avdname.avd, but it is technically incorrect, because you also require ramdisk.img.)
To do this, you need to create your own AOSP repository by downloading the particular repository and have to build your own .img files)
You can do it in two ways:
replace files system.img and ramdisk.img from location .android\avd\avdname.avd
Build your own AOSP. Before... make in "lunch" select target as: Emulator (like: genericX86), i.e., generate all emulator specific .img files
I have tried many things. It's a bit critical, but interesting. The following links may help you:
To run your cooked ROM on Emulator (link down. Try this, from archive.org).
To Create AOSP Project

Eclipse Android SDK ERROR: unknown virtual device name

So, the issue i correctly installed eclipse,android sdk,ndk, coocs2d-x 2.1.4. I can build cocos2d-x android project, import it to eclipse, etc. Everything seems fine, but not really. The problem is that i can't launch my virtual machine to emulate andoid OS. I created avd, it works fine with simple android projects, but when i use it to run cocos2d-x project as android application it does nothing. No output at all. I found this guide and followed it. But i faced a problem. 1st of all, when i follow this step:
Now start the Android for x86 Intel Emulator using the following command:
$ <SDK directory>/tools/emulator-x86 -avd Your_AVD_Name -qemu -m 2047 -enable-kvm
i have an error message:
gloomist-CN tools # ./emulator-x86 #myavd -qemu -m 2047 -enable-kvm
emulator: ERROR: unknown virtual device name: 'myavd'
emulator: could not find virtual device named 'myavd'
But it is in sdk as a valid android virtual device. And the next one. In that tutorial that i pasted link to above, the last step is:
Run the emulator with the correct library path and options
Make sure to
Set the library path to the directory containing the Open GL library for the emulator (LD_LIBRARY_PATH=...)
Run the x86 version of the emulator (run /tools/emulator-x86)
Enable GPU use (Use the option "-gpu on")
Also, you need to specify the name of the Android Virtual Device to use (Use the option "-avd ")
On OS X the command line looks like this
LD_LIBRARY_PATH=~/bin/android-sdk/tools/lib ~/bin/android-sdk/tools/emulator-x86 -verbose -avd android17x86 -gpu on
i don't really know what author meant by all this. Could anyone explain me the way to do it in linux?
So basically, the main problem is: how to run a cocos2d-x project on AVD in eclipse on lixnux? That's it.
I use Linux version 3.2.0-23-generic (buildd#palmer) (gcc version 4.6.3 (Ubuntu/Linaro 4.6.3-1ubuntu4) ) #36-Ubuntu SMP Tue Apr 10 20:41:14 UTC 2012 (Ubuntu 3.2.0-23.36-generic 3.2.14).
Can anyone help me to figure out how can i accurately launch my cocos2d-x project on AVD using eclipse?

Are you sure 'myavd' is a valid avd?
Try to run this command to get a list of AVD's you have created in your system:
# <SDK directory>/tools/android list avd
And re-run emulator-x86 passing a valid avd.
I also suggest you follow the step by step guide about how to configure your android enviroment which comes with cocos2d-x dist. You can find it in: /samples/Cpp/TestCpp/proj.android/README.md
Hope this helps

I was able to fix this error on Ubuntu 18.04 by running:
sudo chmod 777 /dev/kvm
Its not exactly high security, but it gets the job done.

Integrating custom Android kernel builds with SDK

I'm extending a custom Android kernel fork that originated as a 2.2
Froyo kernel. The build process itself is no problem; just type "make"
and its done. But I'm not sure of what I need to do to make the new
kernel known to other tools in the Android SDK; particularly
the emulator, adb, and the Eclipse debugger.
I've tried various things such as running the emulator with -system and
-userdata arguments on the command line, and these appear to work,
although I hit sporatic problems that leave me unsure. A common problem
I've seen is that sometimes apps "hang", displaying their UI but
refusing to go away even when the home or menu buttons are clicked. I've
tried turning off caching. But the real problem here is that I don't
have a good mental model of how kernel builds should be conveyed to
the SDK.
Should I be copying the build results (.img files) to
~/.android/ perhaps? Or to somewhere in the
SDK folder?
A working recipe would be nice, but better yet would be a
understanding of how the kernel build and SDK tools work together.
For example http://source.android.com/source/using-eclipse.html is
great for recipes but I still don't see how adb and emulator know
where to load .img files from.

When you've built android image the android webpage recommends to run it with emulator command. But you can run the built image in this way because android envsetup command has specified some paths before. For instance, to test my built image I run command:
out/host/linux-x86/bin/emulator -sysdir out/target/product/generic/ -system out/target/product/generic/system.img -ramdisk out/target/product/generic/ramdisk.img -data out/target/product/generic/userdata.img -kernel prebuilt/android-arm/kernel/kernel-qemu -sdcard sdcard.img -skindir sdk/emulator/skins -skin WVGA800 -scale 0.7 -memory 512 -partition-size 1024
So as you can see I specify all the images and all the paths explicitly. This is command to run image in emulator. Out folder is created during the build in your android source root folder.
P.S. Kernel usually refers to Linux kernel of Android. In your case, I think you have changed Android framework.

I've composed a full answer based on the invaluable clues Yury provided. The solution was to add these settings to my .bashrc. The tools (emulator, adb, ddms) in eclipse use these settings to pick up stuff from ANDROID_TARGET_OUT instead of getting them from the prebuilt copies inside the SDK. The CACHE stuff is the standard recommendation.
# Android SDK Build settings
export ANDROID_HOME="/Volumes/DroidImg/android-sdk-macosx"
export ANDROID_SDK_ROOT="$ANDROID_HOME"
export ANDROID_SDK_BASE="$ANDROID_HOME"
export ANDROID_SDK_HOME="$ANDROID_HOME"
export ANDROID_TARGET_OUT="/Volumes/DroidImg/Droid-Kernel/out/target/product/generic"
export USE_CCACHE=1
export CCACHE_DIR="/Volumes/DroidImg/CCACHE_DIR"
ulimit -S -n 1024
Finally, copy the .classpath provided with the SDK as documented on the wiki into the root of the kernel distribution, and "import existing files" into Eclipse. All Java components should now open and build properly in the package explorer. Very handy for exploring but don't forget you have to use ordinary make to build this stuff for real.
/Volumes/DroidImg is a case-preserving disk image I made for MAC-OS work; change this part of the path to suit.

Android emulator cannot be started from windows console

I'm trying to run my android emulator on windows console but I get this error:
emulator: ERROR: Your system directory is missing the 'kernel-qemu' image file.
Please specify one with the '-kernel <filepath>' option
how can I fix this?. thanks for tour time.
----- UPDATE -----
I finally can fix this error. At fisrt, I planned to install android SDK offline rather than using SDK Manager. So I followed up this instruction and downloaded the components I need. Everything is correctly except that when I extract the platform using IZArc the file kernel-qemu which located in /platform/images/ is not extracted. But when I manually choose the file from IZArc and drag it to any folder it's extracted. Maybe this is about IZArc configuration but this error cost me for almost a week!

do you have your kernel image file under
< android >/tools/lib/images/
directory?
but i think your problem is your sintaxis to run the emulator
./emulator -kernel kernel-qemu -system
system.img -ramdisk ramdisk.img
-initdata userdata.img -partition-size 512