• open a crosh terminal: CTRL-ALT-t and then launch a shell with shell command under crosh (more crosh options there)

Install debian chroot

What is nice on a linux machine is that you can install in a chroot in parallel of the ChromeOS a full debian: this is achieved using crouton

In order to switch to the "debian desktop" you need to hold jointly CTRL+ALT+SHIFT+FORWARD keys (FORWARD is the key next to REFRESH on the top) when using the xorg XMETHOD otherwise the fullscreen key will do just fine.

Note that you can always delete your chroot via sudo delete-chroot stretch if needed.

Crouton cheatsheet is there if you need to learn more.

Note that chroot filesystem location is stored there /usr/local/chroots/stretch or /media/removable/sdcard/chroots/stretch if you have used the prefix (-p) option.

You can define default XMETHOD in /etc/crouton/xmethod.

Temporary netsurf-gtk installation issue with debian

Debian customization

todo: create aosp/prebuilts/gcc/linux-arm

Overall to reduce size of the cloning of the repo you need to use the two following tricks, i) shallow clone and ii) sync only the current branch (note: it has limitations)

Have fun with programming

Screenshots with Android under linux

MTP with a chromebook

Yes it work with the native chromebook filebrowser and you can enable write suppport with this trick: chrome://flags/#enable-mtp-write-support

screen needs some cleaning at startup

Users are getting permission denied when invoking screen: to get around this add in /etc/rc.local

Useful commands

Some interesting reading

• http://www.galexander.org/chromebook (bootom page)
• https://wiki.debian.org/InstallingDebianOn/Asus/C201
• http://kmkeen.com/c100p-tweaks/
• https://archlinuxarm.org/platforms/armv7/rockchip/asus-chromebook-flip-c100p 
• http://www.linuxveda.com/2016/01/18/how-to-install-arch-linux-arm-on-asus-chromebook-flip/3/
• https://libreboot.org/docs/hcl/c201.html
• http://git.yoctoproject.org/cgit/cgit.cgi/meta-rockchip/about/
• http://git.yoctoproject.org/cgit/cgit.cgi/meta-rockchip/tree/recipes-graphics/xorg-driver/xf86-video-armsoc-rockchip_git.bb?h=master
• https://github.com/rockchip-linux/rk-rootfs-build

Run i386 binaries on armhf architecture

If you need to run some i386 binaries because of the Intel supremacy and people not understanding that Linux is not only x86 you can use qemu (e.g. for k2pdfopt):

Debian upgrade process

Browse network shares

There are two ways to mount SMB network shares with chrome:

• allow user to use fuse

• addgroup fuse and let the user access it

• configure these files to match your network credentials, workgroup and hosts:

• launch the beast:

• to unmount:

Explorations WIP not to be used:

MTP under linux

Follow: hhttps://www.debian-fr.org/t/tuto-montage-auto-dun-appareil-mtp/56505

Automatic mount and unmount via udev new rules and matching ID_MODEL and ID_MODEL_ID and MODEL_ID_ENC running udevadm monitor --environment --udev

Recompile own kernel or specific kernel modules

Practical example: binfmt_misc kernel module recompilation

First you must allow module loading following https://github.com/divx118/crouton-packages/blob/master/README.md i.e. under crosh shell do:

NOTE that the example below is deprecated since now by default chromeos kernel has BINFMT_MISC=yes in the config file.

In order to build your own module detailed instructions are provided here https://github.com/dnschneid/crouton/wiki/Build-chrome-os-kernel-and-kernel-modules which translates when applying to the c201 chromebook device in:

In order to get better performance on armv7 machines and get a working solution, it is advised to use the non free exagear desktop software, some interesting configuration notes are found there http://forum.eltechs.com/viewtopic.php?t=58&p=109

I managed to have office 2007 working using exagear shell through the following steps:

• as a user launch exagear desktop (uname -a will tell you that you are i686 arch):

• then install office 2007
• after this in order not to crash office applications launch winecfg and go in Applications -> Wine -> Configure Wine -> Libraries, search for riched20 then click add and then modify it to choose "native Windows"

You can also add missing windows tools using winetricks following http://nithinaneeshsct06bt.blogspot.fr/2013/02/install-microsoft-office-2010-in-ubuntu.html or http://doc.ubuntu-fr.org/microsoft_office

Note that exagear is a bit overkill because it installs another i386 chroot inside the crouton arm chroot, there might be a way to use the original debian arm chroot with the i386 architecture added. It would result in a tremendous saving in disk space which matters on chromebooks. Question has been asked to exagear developper and the answer is negative :-(.

Section "Device"
        Identifier      "Mali"
        Driver          "modesetting"
        Option          "ShadowFB"              "false"
EndSection
Section "Screen"
        Identifier      "DefaultScreen"
        Device          "Mali"
        DefaultDepth    24
EndSection
Section "DRI"
        Mode            0666
EndSection
Section "Module"
        Disable         "glamoregl"
        Disable	        "fbdev"
EndSection

input driver: the synaptics way

Input driver: the cmt way

Conclusion

Accelerated video decoding

Rockchip linux source code

There is some code released by Rockchip here https://github.com/rockchip-linux 

vp9 https://github.com/rockchip-linux/v4l2_plugin
Video Acceleration API (vaapi) https://github.com/rockchip-linux/rockchip-va-driver/tree/master/src
Video Decode and Presentation API for Unix (vdpau) https://github.com/rockchip-linux/libvdpau-rockchip
ffmpeg https://github.com/rockchip-linux/ffmpeg 

It seems that there is another way to get hw acceleration through libhybris on top of archlinux using this with illustration of the method working.

mpv experimentations

This does crash:

mpv -fs -vo opengl:backend=x11egl:es=yes

gpg

In order to avoid the gtk or ncurses pintentry dialog you can do:

Misc issues

Xiwi not launching because of undefined symbol

I ran into the issue of xiwi not launching because of undefined symbol in xorg dummy_drv.so (ChangeWindowProperty). It was fixed in mergeboat branch and instead of waiting I just did:

sudo CROUTON_BRANCH=mergeboat sh $HOME/Downloads/crouton -u ...

but it did not help.

In order to solve the issue I had to download xf86-server-dummy source from debian stretch, apply the diff and then extract from crouton targets/xiwi script in mergeboat branch the patch and rebuild manually after applying the deb package.

Loss of sdcard after suspend
The utmost annoying problem with chromebooks and crouton is that there is no real solution for already more than 3 years to the problem of loss of sdcard/usb stick after suspend preventing running crouton from external storage. This is really a shame because of the limited storage size of the current chromebooks and lack of ssd upgrade on recent models.
In order to learn more about this problem you can refer to these long threads:
from crouton issue tracker: https://github.com/dnschneid/crouton/issues/288
from chrome issue tracking: https://bugs.chromium.org/p/chromium/issues/detail?id=208380 or https://bugs.chromium.org/p/chromium/issues/detail?id=434372
Please do star these issues so that they get proper notice and support.
Note that none of the previous fixes work now:
usb power persist has been removed from kernel at platform level and from powerd_suspend to gain time in resume preventing usb key to be used (https://chromium-review.googlesource.com/#/c/49018//)
powerd_suspend script tweaking is no longer effective
The problem happens on Toshiba Chromebook 2, Acer Chromebook R11, Asus C201 impacting ARM and Intel platforms.
I have been loosing countless time on this issue and I am very surprised that none of the Googlers that must be using croutong are not doing something about it.
And yes I know that the real answer is; you are welcome to submit a patch.

Issue comes from a modification of the code in disks/suspend_unmount_manager.cc where the unmount of sdcard is handled and a fix would be to get this patch in:

diff --git a/chromeos/disks/suspend_unmount_manager.cc b/chromeos/disks/suspend_unmount_manager.cc
index 795ac9d..2db0e77 100644
--- a/chromeos/disks/suspend_unmount_manager.cc
+++ b/chromeos/disks/suspend_unmount_manager.cc
@@ -36,8 +36,7 @@ void SuspendUnmountManager::SuspendImminent() {
     return;
   std::set<std::string> mount_paths;
   for (const auto& pair : disk_mount_manager_->disks()) {
-    if ((pair.second->device_type() == DEVICE_TYPE_USB ||
-         pair.second->device_type() == DEVICE_TYPE_SD) &&
+    if ((pair.second->device_type() == DEVICE_TYPE_USB) &&
         !pair.second->mount_path().empty()) {
       mount_paths.insert(pair.second->mount_path());
     }

For x86 architecture it will work on devices that are using a non USB based mmc sdcard reader (e.g. Acer R11) and will not with USB based mmc sdcard readers (e.g. Toshiba chromebook 2).
I believe that this suspend_umount_manager.cc should not be a generic code but more architecture or device dependent since many SoC having a direct mmc interface (e.g. ARM) can manage suspend by their own without force unmount.
Note to self: if a chromebook is to be bought check i) to have eMMC solution not soldered on the board (all new chromebooks do not fulfill this requirement unfortunately) to upgrade the internal storage capacity and, ii) if an intel is to be chosen make sure that the mmc controller is not on usb.
Get google play on your C201 (and others) before it is released
Yes this is possible (if there is a mention of ARC in chromeos settings/about version), you just need to fiddle with the chrome dev options and enable ARC:
sudo -i
cp /etc/chrome_dev.conf /usr/local
echo "–enable-arc" >> /usr/local/chrome_dev.conf
mount -o bind /usr/local/chrome_dev.conf /etc/chrome_dev.conf
Disconnect and reconnect and voilà!
Android studio running on ARM chromebook
Note that this section is still WIP. The current status is:
android-studio can be launched and it is possible to build apps with SDK23 and SDK25
native code i.e. android-ndk works sometimes (I get compiler internal error building libav)
Approach is to use a "Frankenstein" hybrid setup faking x86_64 architecture using qemu-x86_64 at the rescue but using ARM based Oracle JDK.
Note that exagear cannot be used since it only supports 32bits and Android SDK is only x86_64 (64bits) (but exagear is working on 64b support but this will be anticipated to be much slower than what is proposed here since what is proposed it to used an hybrid ARM/x86_64-qemued).
Compilation of "simple" java only apps (Android studio and gradle)
You thus need to rely on qemu-x86_64 and properly register x86_64 magic to binfmt for seamless detection and execution:
apt-install qemu-user binfmt-support
echo ':x86_64:M::\x7fELF\x02\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x3e\x00:\xff\xff\xff\xff\xff\xfe\xfe\xff\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff:/usr/bin/qemu-x86_64:P' > /proc/sys/fs/binfmt_misc/register
dpkg --add-architecture x86_64
apt install libc6:amd64
sudo apt install lib32stdc++6
sudo apt install libz1:amd64 libncurses5:amd64 zlib1g:amd64 libstdc++6:amd64
/etc/init.d/binfmt-support start
cd /usr/local/bin/
wget https://raw.githubusercontent.com/qemu/qemu/master/scripts/qemu-binfmt-conf.sh
chmod a+rx qemu-binfmt-conf.sh /usr/local/bin/qemu-binfmt-conf.sh
After this just download and run android studio for linux x86_64 architecture.
Note that android-studio/jre/bin/java fails to execute. In order to solve this issue and boost things up download Oracle ARM jdk, install it in /opt/jdk and point android-studio/jre to this directory /opt/jdk:
/opt/android-studio/jre/bin/java.
Install android-sdk tools command line version:
mkdir /opt/android-sdk
cd /opt/android-sdk
unzip sdk-tools-linux-3859397.zip
cd tools/bin
touch ~/.android/repositories.cfg
./sdkmanager "build-tools;28.0.3"
./sdkmanager "ndk-bundle"
./sdkmanager "platforms;android-28"
./sdkmanager "platforms;android-27"
To make it work you really need to fix aapt (the best is for optimizations).
cd /opt/android-studio
mv jre jre-old
ln -s /opt/jdk /opt/android-studio/jre
cd /opt/android-sdk/build-tools/25.0.2
mv aapt aapt_
sudo apt install aapt
ln -s /usr/bin/aapt
for p in apksigner aidl dexdump zipalign split-select dx
do
 sudo apt install $p
 mv $p ${p}_
 ln -s /usr/bin/$p 
done
sudo apt install android-sdk-build-tools-common
sudo apt install dalvik-exchange
You need also to add a couple of i386 and x86_64 libraries to do some builds:
dpkg --add-architecture i386
sudo apt install libz1:i386 libncurses5:i386 zlib1g:i386 libstdc++6:i386 lib32z1 libc6-i386 lib32stdc++6 lib32gcc1 lib32ncurses5
Can we go one step further and enable NDK support?
What follows is the WIP to support android-ndk which works sometimes. If you do not need it you can stop there.
Modify android NDK to force armv7l detected as x86_64 to use binfmt and qemu:
diff --git a/build/core/init.mk b/build/core/init.mk
index 56e5f300..328a81b6 100644
--- a/build/core/init.mk
+++ b/build/core/init.mk
@@ -242,6 +242,9 @@ ifndef HOST_ARCH
 ifneq (,$(findstring Power,$(UNAME)))
 HOST_ARCH := ppc
 endif
+ ifneq (,$(findstring arm,$(UNAME)))
+ HOST_ARCH := x86_64
+ endif
 ifeq ($(HOST_ARCH),)
 $(call __ndk_info,Unsupported host architecture: $(UNAME))
 $(call __ndk_error,Aborting)
@@ -363,7 +366,7 @@ $(call ndk_log,Host 'cmp' tool: $(HOST_CMP))
 #
 HOST_AWK := $(strip $(HOST_AWK))
 ifndef HOST_AWK
- HOST_AWK := awk
+ HOST_AWK := gawk
 endif
 $(call ndk_log,Host 'awk' tool: $(HOST_AWK))

diff --git a/ndk-build b/ndk-build
index 62d6dc8c..dc353037 100755
--- a/ndk-build
+++ b/ndk-build
@@ -143,7 +143,7 @@ log "HOST_OS=$HOST_OS"
 HOST_ARCH=$(uname -m)
 case $HOST_ARCH in
 i?86) HOST_ARCH=x86;;
- x86_64|amd64) HOST_ARCH=x86_64;;
+ x86_64|amd64|armv7l) HOST_ARCH=x86_64;;
 *) echo "ERROR: Unknown host CPU architecture: $HOST_ARCH"
 exit 1
 esac
Some platform tools are complaining to be obsolete: instead of using x86_64 ones link them back to native ARM one with a boost in performance benefit:
cd android-ndk/prebuilt/linux-x86_64
for f in awk perl python2.7 yasm
do
 mv $f "$f"_
 ln -s /usr/bin/$f 
done
mv sed sed_
ln -s /bin/sed

For some reasons a lot of x86_64 from NDK when run are not properly recognized by binfmt and qemu-x86_64 has to be forced.
For this purpose I use following fixqemu.sh script
#!/bin/sh

p=`dirname $1`
f=`basename $1`
if [ -f qemu-"$f" ]
then
  exit
fi
mv "$f" qemu-"$f"
cat > "$1" <<EOF
#!/bin/sh
p=\`dirname \$0\`
f=\`basename \$0\`
exec qemu-x86_64 "\$p"/qemu-"\$f" "\$@"
EOF

chmod a+rx "$1"
This needs to be applied to all the files identified by find . -type f -exec file {} \; | grep executable | grep ELF | grep -v qemu
I applied this to several binaries in the android NDK:
cd android-ndk/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/libexec/gcc/arm-linux-androideabi/4.9/
for f in cc1 cc1plus collect2 lto-wrapper lto1
do
 fixqemu.sh $f
done
cd android-ndk/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/bin
find . -type f -exec /home/marc/fixqemu.sh {} \;
ln -s qemu-arm-linux-androideabi-gcc qemu-arm-linux-androideabi-gcc-4.9
ln -s qemu-arm-linux-androideabi-ld.gold qemu-arm-linux-androideabi-ld
ln -s qemu-arm-linux-androideabi-g++ qemu-arm-linux-androideabi-c++
ln -s ../../../../../toolchains/llvm-3.5/prebuilt/linux-x86_64/bin/qemu-ld.mcld qemu-arm-linux-androideabi-ld.mcld
cd android-ndk/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/arm-linux-androideabi/bin/
for f in *; do ln -s ../../bin/qemu-arm-linux-androideabi-$f qemu-$f ; done
rm qemu-ld
ln -s ../../bin/qemu-arm-linux-androideabi-ld.gold qemu-ld
rm qemu-ld.mcld
ln -s ../../../../../../toolchains/llvm-3.5/prebuilt/linux-x86_64/bin/ld.mcld qemu-ld.mcld
ln -s ../../../../../../toolchains/llvm-3.5/prebuilt/linux-x86_64/bin/qemu-ld.mcld qemu-ld.mcld
cd android-ndk/toolchains/llvm-3.5/prebuilt/linux-x86_64/bin
for f in clang ld.mcld llc llvm-ar llvm-as llvm-dis llvm-link ndk-bc2native ndk-link ndk-strip ndk-translate opt ; do $HOME/fixqemu.sh $f; done
ln -s qemu-clang qemu-clang++
or f in ndk-link ndk-strip ndk-translate; do ln -s qemu-$f qemu-le32-none-$f; ln -s qemu-$f qemu-le64-none-$f; done

cd android-ndk/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/libexec/gcc/arm-linux-androideabi/4.9/plugin
fixqemu.sh gengtype
Is there any binary that I missed that is not a shell script:
find -type f -executable -exec file -i '{}' \; | grep 'x-executable; charset=binary' | grep -v qemu
Check that all links have been processed:
find . -type l -exec ls -l {} \;
Go full native instead?
cd android-ndk/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/libexec/gcc/arm-linux-androideabi/4.9
for f in cc1 cc1plus collect2 lto-wrapper lto1; do mv $f $f.orig ; ln -s /usr/lib/gcc/arm-linux-gnueabihf/6/$f; done
cd android-ndk/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/bin
for f in addr2line ar as c++filt cpp dwp elfedit g++ gcc ar nm ranlib gcc-ar gcc-ar gcc-nm gcc-ranlib gcov gcov-tool gdb gprof ld ld.bfd ld.gold nm objcopy objdump ranlib readelf size strings strip; do mv arm-linux-androideabi-$f arm-linux-androideabi-${f}.orig; ln -s /usr/bin/$f arm-linux-androideabi-$f; done
cd android-ndk/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/arm-linux-androideabi/bin
for f in ar as ld ld.bfd ld.gold nm objcopy objdump ranlib strip; do mv $f ${f}.orig; ln -s /usr/bin/$f ; done
sudo apt install llvm
Well for not it does not work.
cd android-ndk/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/lib/gcc
ln -s arm-linux-androideabi arm-linux-gnueabihf
cd android-ndk/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64
ln -s arm-linux-androideabi arm-linux-gnueabihf
cd android-ndk/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/libexec/gcc
ln -s arm-linux-androideabi arm-linux-gnueabihf
Check what is called with strace and do all symlinks...
Tedious work... and does not work.
mdns
In order to get multicast zeroconf service such as mdns you need to:
apt install avahi-daemon avahi-utils libnss-mdns
/etc/avahi/avahi-daemon.conf
hostname=mark32
disable-publishing=yes
Access local Android via adb on chromebook
In crosh domain:
# to be done once for all
sudo crossystem dev_boot_signed_only=0
sudo /usr/libexec/debugd/helpers/dev_features_rootfs_verification
sudo reboot
sudo /usr/libexec/debugd/helpers/dev_features_ssh
Go in chromebook settings->search for android->GooglePlay settings->android preferences->about->click 5 times on build to be a developer and then switch on adb under developer settings.
Connect to Android under chroot via (not using localhost:22 as advised https://developer.android.com/topic/arc/studio):
adb connect 100.115.92.2:5555
Afterwards you can install any application via adb that you have locally compiled and run it without an emulator: sweet!
If you experience issues and you cannot see any devices after connecting with adb devices try through Android settings to revoke all adb authentication tokens and cycle off/on adb. 

END