Today we learn more about our Android devices and about the possibility to install an alternative operating system for them. First, we learn how to speak to our device from the computer.
- plug in USB
- on Mac:
system_profiler SPUSBDataType - on Linux:
lsusbandlsusb -a
[..]
SAMSUNG_Android:
Product ID: 0x6860
Vendor ID: 0x04e8 (Samsung Electronics Co., Ltd.)
Version: 4.00
Serial Number: 8fc8ffff
Speed: Up to 480 Mb/sec
Manufacturer: SAMSUNG
Location ID: 0x14200000 / 27
Current Available (mA): 500
Current Required (mA): 96
Now we have to make sure that our phone is ready to receive commands via USB.
Quickly tap on the "Android version" field 4-5 times. Tap as fast as you can and it'll launch a secret Easter egg!
Now let's enable USB debugging.
Settings> Applications> Development> USB Debugging
Settings> Developer Options> USB Debugging
If developer options are hidden, go to Settings > About and tab on the "Build Version" 7 times. Then enable Settings> Developer Options> USB Debugging.
The options are hidden by default and we have to enable them. Open Settings> About. If you have a Samsung Galaxy S3, S4, Note 8.0, Tab 3 or any other Galaxy device with Android 4.2 or Android 4.3, open Settings> More/General tab> About and tap it. If you have Galaxy Note 2 or Note 3 or any Galaxy device with Android 4.3, go to Settings> General> About. Now scroll to Build number and tap it 7 times. You will see a message “You are now a developer!” or “Developer mode has been enabled”. Return to the main Settings menu and now you can see Developer Options. Tap on Developer options and mark the box in front of USB Debugging to enable it. To disable USB Debugging mode later, you can uncheck the box before the option. Some devices have a slider instead of a check box.
Go to Settings> About> Software Information> More. Tap “Build number” seven times to enable Developer options. You will see a “You are now a developer!” message. Go back to the Settings and you can see “Developer options”. Tap it and turn on USB Debugging.
Go to Settings> About> Software Information. Tap "Build Number" seven times. You will see a “You are now a developer!” message. Go back to Settings and you can see Developer options. Tap it and enable USB Debugging.
Newer Linux distributions have adb in their repositories. For Ubuntu 12.10 and later, run the following command:
sudo apt-get install android-tools-adb
If we have no internet, double click on the .deb file or move it to /var/cache/apt/archives and then install as above.
Or for Fedora 18/19:
sudo yum install android-tools
Or on OSX using Homebrew:
brew install android-platform-tools
Find out where Homebrew's downloaded files are with brew --cache - here you have to put your source file if we have no internet.
If your distribution does not have packages for adb available (i.e. Ubuntu 12.04 or Fedora 17), you'll need to install the Android SDK starter package for your platform (you'll want the ADT Bundle, not the SDK Tools Only option). Then run their package manager, $SDK_HOME/tools/android, and use the GUI to install "Android SDK Platform-tools".
Find out where adb is installed (usually in usr/bin, possibly additionally inside adt/platform-tools, depending on how you installed it). Be sure to add this directory to your PATH. This can be done by adding the line
PATH=$SDK_HOME:$PATH
replacing $SDK_HOME with the location of the android sdk, to your ~/.bashrc or equivalent.
$ adb shell
* daemon not running. starting it now on port 5037 *
* daemon started successfully *
error: device unauthorized. Please check the confirmation dialog on your device.
Look at your phone and allow access from your computer. Then try again.
$ adb shell
shell@jfltecan:/ $
You can always exit the shell by typing exit.
Android devices have three kinds of storage:
- RAM,
- internal flash storage,
- removable storage on an SD card.
RAM or internal memory is very fast, read-write, and volatile, meaning it "forgets" data when the device is turned off. RAM is the 'short term' memory that the device uses when it's actively 'thinking' or processing. For apps to run, they must first be 'loaded' from the internal storage into RAM memory. When an app is closed, it is then removed from RAM to make room for other programs.
Internal storage, also known as flash memory, flash storage, or the eMMC (Embedded MultiMedia Card), is keeping information even when the device is off. Internal storage in the device works like a hard drive in a computer. This is where the device's operating system (sometimes called "firmware"), apps, user data, and more are stored. Internal storage is generally slower than internal memory (aka "RAM").
The SD card is a removable flash memory storage media for example for pictures and music. You can buy SD cards at most electronic stores and can swap them out when storage runs low on your device.
Android devices have their internal flash storage divided into partitions. A partition is like a room in a house. Just as each room has a specific purpose, each partition has a specific purpose. Additionally, directories (or folders) are used to organize information.
Let's look at some of the most common partitions and their corresponding directories (yours might be different).
/boot stores the kernel and ramdisk. The kernel can be thought of as the "core" of the device's software. It is what allows the hardware to talk to the software. It determines in which file format information can be stored. The ramdisk contains the very first bits of Android that are loaded. It's the software that loads everything else.
/recovery holds the device's recovery software, which gives the user access to functions for upgrading or the operating system or making a backup of the device's software.
/system the most important software, the operating system itself, is stored here. When CyanogenMod is installed, this is where it goes. Usually, this partition is loaded into "read only" mode so that you don't accidentally overwrite portions of Android. You only make it writeable for the time while you upgrade Android or install Cyanogenmod.
/cache This directory stores temporary files used by Android. Files on this partition are not critical to the operation of the device, and can be "cleared out" by wiping its contents, especially during every major upgrade.
/data much of your personal data is stored here. So if you download an app from the Play Store, it goes here. If you change a setting, that change is also stored here. If you receive a SMS, it too is stored here.
/sdcard contains the stuff from your removable media, such as an SD card. It is used by many apps as a general purpose download space. You can put movies and such on here as well. Even devices without a removable SD card slot may have an /sdcard directory. In this case, it is usually "linked" to a folder in internal storage.
Source: http://wiki.cyanogenmod.org/w/Doc:_more_concepts
Partitions can contain different data or even different operating systems. When booting up a computer or device, we can choose a "boot partition" and then the operating system on that partition will be run.
We can see all currently used partitions by running a command in adb shell
shell@jfltecan:/ $ cat /proc/partitions
These names look very cryptic!
We can see readable names that are given on "mounting" the partitions (the process of opening them and adding them to the ones available in the current running system).
shell@jfltecan:/ $ mount
A short list we can find by looking at the /dev/block/platform directory - so let's have a look!
1|shell@jfltecan:/ $ ls /dev/block/platform/
msm_sdcc.1
msm_sdcc.2
ls /dev/block/platform/msm_sdcc.1/by-name/
aboot
apnhlos
backup
boot
cache
carrier
efs
fota
fsg
hidden
m9kefs1
m9kefs2
m9kefs3
mdm
modemst1
modemst2
pad
param
persdata
persist
recovery
rpm
sbl1
[..]
Recovery is an Android-based, mini operating system separate from the main Android operating system on the device. It is stored on a different disk partition than the main Android partitions (boot/kernel, root/system). It contains its own Linux kernel. Because it has this own separate kernel and recovery apps, the device is able to boot into the recovery mode even if the main system is broken, allowing the user a set of tools to fix the device.
The bootloader determines whether to boot Android or Recovery, based on which buttons you press while turning the device on.
The open-source community has extended the Android Recovery system to add other features:
- system backup and restore (NANDroid),
- ability to apply Android changes that aren't approved by the manufacturers or carriers
- improved user interface, including using the touch screen instead of only the volume and power buttons, and runs adbd, to support ADB connections.
The most popular custom recovery is ClockworkMod Recovery.
To get a custom recovery, many manuals suggest reflashing the recovery partition (overwriting it). This is dangerous and if you do something wrong you can "brick" your device (break it forever). Even though the built-in recovery might be very simple (if there is one), it is able to run update.zip from a microSD card. This allows you to run the custom recovery application from the SDcard without flashing it to the device itself.
Enter recovery mode by pressing a button combination during the boot sequence of the device. When these keys are pressed, the device does not boot Android as usual. Instead, it boots the recovery partition, kernel and recovery apps are loaded from this partition, and the rest of the flash storage is untouched. What is flashed on the recovery partition, will be run. Sometimes there is no recovery flashed by the manufacturer, so even if the recovery mode keys are pressed, no recovery mode is happening. You then can still flash your own recovery to the device with Odin mode and use it later.
Samsung Galaxy phones have their own recovery mode with simple "ClockworkMod Recovery" in its stock firmware. Extended CWM can be flashed via Odin mode or from the stock recovery mode. Enter recovery mode this way:
- Power off the device
- Press Volume Up + Home + Power ON buttons at the same time and hold them pressed
- Most Galaxy devices boot twice to enter recovery mode, so just hold keys pressed and wait release buttons when CWM announces itself
- use Volume Up/Down and Home button to pick menu entries Some Samsung devices (Samsung Galaxy Tab series) have no Home hardware button. These devices may require only Volume Up + Power ON to be pressed during boot.
Source: http://forum.xda-developers.com/wiki/Recovery
Rooting your device means that you gain superuser access on the device. Superuser is a user that can do anything on the device, like for example delete each file. These special powers are required for some more complex operations where you have to access or move system files. Apps may request root access, for example TitaniumBackup, an App for backing up all files including system files, or Orbot, a Tor client for Android which can wrap your traffic in many onion layers of encryption. In a stock Android the superuser access is usually not available (the phone is "not rooted"). The manufacturers claim this is to prevent the user from destroying the system, but we could also say it restricts the owner of the phone from taking full control over his or her device!
For installing Cyanogenmod, rooting the device is only necessary when you want to install it via the Clockworkmod recovery installer app, which requires superuser powers (to overwrite the recovery partition?). Rooting the device comes for free with Cyanogenmod, it is build into the Cyanogenmod system already.
CyanogenMod (pronounced /saɪ.ˈæn.oʊ.ˌdʒɛn.mɒd/) is an open source operating system for smartphones and tablet computers, based on the Android mobile platform. It is developed as free and open source software based on the official releases of Android by Google, with added original and third-party code. It does not contain spyware or bloatware. In many cases, it may increase performance and reliability compared with official firmware releases.
http://wiki.cyanogenmod.org/w/About
ROM, operating system, firmware are all synonyms when we speak about an Android device. There are many more custom ROMs out there, Cyanogenmod being the most popular one.
go to http://get.cm/app it leads you to http://beta.download.cyanogenmod.org/install and follow the instructions. You will install an app on your phone, and a Software on your Mac or Windows PC, just follow the step by step instructions. These together will install Cyanogenmod on the system partition of your phone.
Install Clockworkmod or load it from SDcard via your preinstalled recovery mode (see above), or maybe you have Clockworkmod already because you have a Samsung phone (test like above).
Find out what Cyanogenmod version you need for your device, either by device name or by looking at the Model Number in "Settings->About Phone" on your phone and searching that in the Cyanaogenmod or xda-Developers pages (can be useful if you have a rare model).
Download Cyanogenmod from http://download.cyanogenmod.org/, for example a stable release from http://download.cyanogenmod.org/?type=stable. The nightly builds may have more features, but also crash because they are not stable, it is up to you what you choose.
Check if the file is correctly downloaded by comparing it's checksum with the one on the download page:
md5 <filename> or md5sum <filename>.
Put the file on the SDcard (via a cardreader or connecting in your device via USB and then Filebrowser or adb push).
Boot into Clockworkmod and select upgrade, then select the cyanogenmod zipfile. Reboot. Done. :)
Samsung devices can be put into Odin mode, where the phone waits for commandline instructions to overwrite it's memory.
This is dangerous, since you can write to the wrong partition, and overwrite system and recovery, which will destroy your phone irreversibly. To send the new firmware/operating system to your phone, you need the Odin Software for Windows or the cross-platform alternative Heimdall.
I have used this method on my old phone (Samsung Galaxy SII) and it worked well, but I encourage you to read elsewhere about it before you try it out.
- no store at all - go apk
- F-Droid vs. play store
- google apps
- Redphone
- Orbot & Torbrowser
- Xabber & OTR
- Textsecure
- No Google account or empty google account
- No sync to Google (I sync to CardDAV on OwnCloud)