Skip to main content
New
Stack Overflow Jobs powered by Indeed: A job site that puts thousands of tech jobs at your fingertips (U.S. only). Search jobs
14 votes
Accepted

Is kernel mode of operating system and root permissions in android same thing?

Root permissions and kernel mode are not the same thing. Programs with root access can access part of the kernel, but root is not the kernel itself. The Android (and Linux) user model has a set of ...
gertmenkel's user avatar
12 votes
Accepted

How can I enable last_kmsg?

Back in 2012, /proc/last_kmsg (1) used to be a dump of kernel console messages, exported after reboots by Android's ram_console functionality (CONFIG_ANDROID_RAM_CONSOLE), which used persistent_ram (...
Irfan Latif's user avatar
  • 20.6k
11 votes
Accepted

How to make Ethernet work on Android over OTG?

There is a long list of Ethernet related questions but none has a comprehensive answer covering all aspects. I'm generalizing your question in order to share my knowledge on this. This is what you ...
Irfan Latif's user avatar
  • 20.6k
10 votes

Backup/dump kernel image without root or twrp/cwm

It is possible to dump device partitions without root or custom recovery - if your device has "fastboot" mode and is boot unlocked. I'm not going to describe unlocking the boot loader, but with a ...
Guss's user avatar
  • 201
9 votes

What is the difference between the Linux Kernel and the Android Kernel?

I think this Android Source is a great documentation for understanding it. And here is a list of changes done from mainline kernel for android kernel 4.14. The largest features include: 19.8% ...
chankruze's user avatar
  • 189
9 votes
Accepted

Is it possible to flash a boot.img kernel with TWRP?

Boot into TWRP, select Install and follow the screenshots for the rest. (Click image to enlarge) It's not a problem for TWRP to which ROM your particular kernel belongs. The size should not be ...
Firelord's user avatar
  • 25.1k
8 votes
Accepted

Why does Android differ so much from Linux?

Why didn't Google just take a Linux distribution ... and create a desktop environment for touchscreens? Because they didn't want to create a desktop environment for touchscreens: they wanted to ...
Dan Hulme's user avatar
  • 35k
8 votes
Accepted

Booting kernel from fastboot

When you use fastboot boot FILE.img, the image is downloaded and written into the RAM and than the normal procedure to boot a boot.img is followed. No changes to any partition takes place. If the ...
Firelord's user avatar
  • 25.1k
8 votes
Accepted

Backup/dump kernel image (and full ROM) without root for Mediatek Devices

To answer my own question! Warning, in some very rare cases this doesn't work or could be dangerous. For example, Amazon Fire devices refuse to communicate with these tools despite being MediaTek. ...
Sruly's user avatar
  • 988
6 votes
Accepted

What happens if you install another phone's kernel on yours?

At a simple level, the effects would be catastrophic. The system wouldn't boot, and you would probably hard-brick OR super-brick. Kernels are the direct system for managing communication between ...
Dan Brown's user avatar
  • 1,731
6 votes
Accepted

Is it possible to extract the kernel and device tree from a rom?

If it was that easy then we'd have custom ROMs in no time for every phone on the planet. What's on our phone are compiled, it's basically impossible to decompile them (modern decompilers are not as ...
Andy Yan's user avatar
  • 9,539
6 votes
Accepted

What is needed to run ELF binaries compiled from android APKs? (understanding android internals)

What is needed to run ELF binaries compiled from Android APKs? A simple hello world app which does nothing except printing Hello World! (no animations, no sounds, no menus), running on Android 9 ...
Irfan Latif's user avatar
  • 20.6k
5 votes
Accepted

Can IMEI number of a device really be changed

IMEI is an baseband identifier so it's stored on non-writable memory. There are two IMEIs actually - display and hardware. It's possible to change the display IMEI on rooted devices, but no way to ...
Tomáš Pánik's user avatar
5 votes
Accepted

Building ROMs & Kernels?

1) Building in Android could mean: - building a deliverable in the android build tree - building a deliverable on an android platform having build tools installed - building the AOSP (Android ...
Rémi Cohen-Scali's user avatar
5 votes
Accepted

CPU-Z shows 8 cores, but 4 of them are stopped

Is there any way of activating all cores? You can't. The hardware is not designed to have all 8 cores active. The reason for this is that this Octacore CPU is actually based on big.LITTLE technology,...
Lie Ryan's user avatar
  • 19.1k
5 votes

Where are kernel modules installed?

There are two ways Linux kernel modules are built: 1. as a part of kernel executable binary (compressed image) i.e. with CONFIG_*=y options at build time, or 2. as separate kernel object (.ko) files ...
Irfan Latif's user avatar
  • 20.6k
4 votes
Accepted

Can system apps be enabled/disabled directly from the filesystem?

Whether an app is enabled or disabled is stored in a single file /data/system/users/0/package-restrictions.xml. I took the following steps to re-enable the Google App and solve my bootloop problem: ...
Marc.2377's user avatar
  • 484
4 votes
Accepted

Application Sandboxing in Android

Every single application that is installed on your phone, gets a UID. It is a number that Android uses to identify the apps so it can check from what app commands are executed and check the ...
SarpSTA's user avatar
  • 2,682
4 votes

How can /proc/sys values be changed at boot (sysctl.conf does this on normal Linuxes)?

Use init's write command in /init.rc or any other .rc file. You may also create your own: # /system/etc/init/custom.rc on property:sys.boot_completed=1 write /proc/sys/kernel/hostname MyDroid ...
Irfan Latif's user avatar
  • 20.6k
4 votes
Accepted

SELinux permissive kernel - is it a security risk?

SELinux is a security framework which restricts (kernel and userspace) processes within their domains according to defined policy. So the ultimate goal is to load a working policy, label filesystems ...
Irfan Latif's user avatar
  • 20.6k
4 votes
Accepted

Native Linux on Android's SOCs

The main reason: There is no revenue-generating stream for Linux on smartphones in comparison to Android. Technical reasons, which can't be solved without heavy investments Just porting Linux to SoC ...
LVitya's user avatar
  • 156
3 votes

How can I check if a device is booted into safe mode from adb?

Aha! This'll do the trick! Android's dumpsys display command: $ adb shell dumpsys display|grep mSafeMode mSafeMode=true
Dan's user avatar
  • 440
3 votes
Accepted

Can I flash a custom ROM and a separate custom kernel after?

Yes, flashing a kernel is mostly safe. The worst thing that could happen would be a boot loop aka soft brick, which can be fixed by flashing another, proper kernel. Remember that the kernel in your ...
GiantTree's user avatar
  • 4,062
3 votes
Accepted

Why isn't Android using kernel v4+?

Google's Android specific features were not included in the mainline Linux development. So they took the then LTS branch and added their own code. Android does not use or include the native GNU C Lib, ...
ThorX2's user avatar
  • 174
3 votes
Accepted

What does the ROM files (FACTORYFS, HIDDEN, CACHE, PARAM, etc.) mean?

From [INFO] What the ROM files mean boot.bin This is the Primitive Bootloader. Seems to make some basic initializations and finally loads the secondary bootloader. Sbl.bin The Secondary ...
Édouard Lopez's user avatar
3 votes

What linux distribution is Android based on?

It's a modified Linux kernel plus modified libraries designed to run on a closed source architecture. The GUI is its own thing with no source-able materials, also partially why Google spent billions ...
slegg's user avatar
  • 31
3 votes
Accepted

How to brick android

You can easily root the phone (or do this in a working recovery) then run the following command in a shell: dd if=/dev/zero of=/dev/mmcblk0 bs=1M count=1 Do note that unless you destroy a piece of ...
iBug's user avatar
  • 7,767
3 votes

Where to find information about WiFi connectivity of the device?

You can use various Wifi/network analysis apps from Play Store to get some of the information you're looking for. I suggest IP Tools. In its default screen/view, you would get to see following ...
Firelord's user avatar
  • 25.1k
3 votes
Accepted

How do I change the Battery Percentage that corresponds to a Voltage in Android

Let's look at the challenges you would face in achieving correct reading, rooting is not a magic key that let's you do everything easily: The battery capacity (mAh) is coded in two places - the ROM ...
beeshyams's user avatar
  • 41k
3 votes
Accepted

Default kernel version of Android-x86 ISO

How can I know what is the default kernel version? By reading the release notes. With every new release, the development team publishes the major changes compared to the previous releases. The kernel ...
Reddy Lutonadio's user avatar

Only top scored, non community-wiki answers of a minimum length are eligible