Questions tagged [kernel]

The kernel is a central component of most computer operating systems. It acts as bridge between applications and the hardware and also manages the systems's resources.

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How to make Ethernet work on Android over OTG?

I am trying to use an LTE modem connected to an Android 7 device over an OTG cable. The kernel recognizes the device and registers it with cdc_ether, but I am unable to use the connection from the ...
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170 votes
9 answers
64k views

What is the difference between: Rooting, Jailbreaking, ROM, Mod, etc.?

What is the difference between: Unlocking the bootloader (prerequisite for doing many, though not all, other things below) Rooting Jailbreaking ROM NAND and Nandroid Operating System Mod (e.g. ...
7 votes
1 answer
12k views

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

I would like to pull the boot image of my device Pipo N7. I don't have root. I found the following link: Backup/dump kernel image without root or twrp/cwm` But when I try to find /dev -name 'by-name'...
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51 votes
1 answer
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Which Android runs which Linux kernel?

Is there a list of which kernel version comes in each Android AOSP version? Or lets say, which version /proc/version would spit out.
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6 votes
2 answers
9k views

How can I enable last_kmsg?

I'm trying to diagnose a random reboot on LineageOS 14. last_kmsg is not in /proc, nor it is in /sys/fs/pstore/console-ramoops. EDIT: ~# mount | grep PSTORE ~# mkdir /mnt/pstore && mount ...
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78 votes
3 answers
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What linux distribution is Android based on?

Did Google use some existing distribution (Debian, Red Hat, etc.) to create Android, or did they use the bare essentials (kernel, file system and some mandatory files)?
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18 votes
3 answers
17k views

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

What are the modifications done in linux kernel to make it an android kernel ? By this question I mean what are the differences between linux kernel and android kernel ?
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19 votes
6 answers
14k views

Why are there so many different Android kernels?

Isn't Android a common kernel that is used across all devices? For example, CentOS will install on Dell, HP, and a variety of other hardware. Sure there are different modules, but it's still CentOS ...
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1 vote
1 answer
496 views

Is it possible to add a driver to my kernel without flashing a new kernel? [duplicate]

Is it possible to load a driver as a kernel module into my Galaxy S10, Magisk rooted without having to build a new kernel and flash it?
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5 votes
1 answer
2k views

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

I'm trying to understand how Android works internally. Before ART, it used Dalvik to run java code. I guess it created a Dalkiv process in 'Linux' kernel which was simply a VM that ran the dex ...
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3 votes
3 answers
20k views

Get root or re-install the OS without a USB cable?

Usually, the guides for getting root or re-installing the OS on an Android device (I have a Samsung Galaxy S, which I'm mostly inetersted about) tell to flash the device from another computer through ...
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2 votes
1 answer
1k views

How to load kernel module with Magisk root but without custom kernel?

I am having a really hard time finding anything about this on Google which is not from 2011. I have a Samsung Galaxy S10+. I have rooted it with Magisk without TWRP, i.e. no custom recovery or custom ...
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2 votes
1 answer
747 views

Why is TRIM not supported on encrypted "/data" partition?

I have a rooted Lenovo A369i. I use LagFix (fstrim) to TRIM partitions. Previously it was working well with /data but after I encrypted my phone it doesn't. I decrypted my phone by formatting. But now ...
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5 votes
2 answers
5k views

Where are kernel modules installed?

I am trying to find Linux kernel modules on my nitrogen board. I have unpacked kernel config from /proc/config.gz and I see kernel was compiled with a lot of modules. I see only one in /vendor/lib/...
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3 votes
1 answer
4k views

SELinux permissive kernel - is it a security risk?

As in title. I am talking of Kernel, not ROM (plenty of questions dealing with ROM on this site). I have a OnePlus 7 running stock Android 10 and prefer a custom kernel. Of late, OnePlus hasn't ...
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3 votes
0 answers
252 views

Unable to take kernel logs on a non-rooted device [duplicate]

I am trying to take kernel logs but so far have only got errors like 'permission denied', 'path does not exist' or 'kernel log does not exist'. I have tried this kernel panic link, this crash logs ...
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7 votes
5 answers
50k views

How to find out if my Device's Kernel has Loop Device Support

I would assume most all of you know why I am asking this, but for those who don't, Loop Device Support of a Kernel on an Android device is utilized to mount a Linux Distro IMG file (Ubuntu or Debian, &...
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3 votes
1 answer
1k views

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

System apps can be disabled by using pm disable [appname] and re-enabled in the same fashion. But is there a way to accomplish the same thing by editing some file(s?) somewhere? Context: My Android-...
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3 votes
1 answer
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How can I backup and restore Cyanogenmod 12.1 rom installed on my Samsung Galaxy 2 i9100?

Cyanogenmod(12.1)'s recovery has no backup or restore option. As I read in the answer of a previous post, CyanogenMod recovery is basic, so we should flash another recovery. The easiest way would be ...
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7 votes
2 answers
4k views

Given that every application runs as a separate user, what happens when you want to add a new user account?

According to this, every application in Android runs as a separate kernel-level user, with a unique user ID and group ID. So, what happens under the hood when you add a new user (e.g. to your shared ...
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4 votes
1 answer
36k views

How can I update the Linux kernel of my Android device?

I am using Sony Xperia E Dual with the kernel that identifies as 3.0.8-perf administrator@ubuntu-scm01 #1 and now I want to update it to the latest and the best one. Please help me understand it can ...
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3 votes
2 answers
28k views

Backup/dump kernel image without root or twrp/cwm

Is there any way to backup/dump kernel image without root or twrp/cwm ?
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3 votes
1 answer
1k views

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

How can /proc/sys values be changed at boot? sysctl.conf doesn't exist on Android and echoing values to the proc files isn't persistent.
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3 votes
1 answer
3k views

Does Cyanogenmod Kernel support loop devices?

Since I am failing to mount a Nandroid image and since I have read that the kernel needs to support loop devices for that I need to know if anybody has managed to mount a loop device on CM7 or similar....
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  • 507
2 votes
1 answer
4k views

Booting kernel from fastboot

We all have heard of "fastboot boot xxxx" command. How does it work when you use it for kernel (fastboot boot boot.img)? Is it simple as this: it boot Android with that kernel if possible or it make ...
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1 vote
1 answer
1k views

Why files/directories under Android's root filesystem don't change across different version updates?

I compared 2 devices; one running Android v5.1.1 and other v9.0. So I noticed that files under /proc are same in both. Can anyone explain why there is no difference even though OEM's are different and ...
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8 votes
1 answer
8k views

l2_hsic prevents my device from Deep Sleep. How to fix it?

I have installed BetterBatteryStats and CPU SPY, because I noticed that I had a faster than normal battery consumption when the tab was left alone. I made a 30 mins test Wifi OFF, Flight Mode On, ...
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4 votes
1 answer
6k views

Where can I configure SELinux in Cyanogenmod 10.1.3?

Cyanogenmod released the stable version 10.1.3 yesterday and it apparently includes SELinux enhancements running in permissive mode per default. I thought that you could change the mode in the ...
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3 votes
0 answers
5k views

Why does the Kernel and Android System/Android OS drain my battery?

3 hours since unplugging my phone, and at light usage it's at 61%. It is the kind of problem I've had with my previous phone, and I have with my current phone, often starting a few months in and ...
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  • 131
3 votes
1 answer
197 views

Salvage Android Phone as Linux-Server (radio/wifi hardware broken)

My device has hardware problems with radio/wifi. Hence it's not possible to use sim-card or wifi. That also makes it restart frequently. Now it's useless as a phone. So I am trying to turn it in a ...
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3 votes
1 answer
34k views

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

I'm looking to flash a ROM's boot.img on another ROM with TWRP 3.0. Is it possible? If it's relevant, both ROMs are CM-based running Android 5.1 Lollipop.
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2 votes
1 answer
2k views

How do I load an unsigned Kernel Module to my signature enforcing Kernel?

I compiled a kernel module (wacom.ko) using the proper kernel source for my device and Google toolchain. When I tried to insmod the module, an error message popped up saying required keys not ...
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2 votes
1 answer
1k views

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

Is it possible to use adb to detect whether a device is booted into "Safe Mode" or normal mode? I've looked through the output of getprop and other command-line tools and haven't found any good ...
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  • 440
2 votes
1 answer
6k views

Why is EXT3 not supported on Android?

Android uses the Linux kernel instead of some "Android kernel", so why is ext3 not supported on Android 2.3?
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1 vote
1 answer
495 views

mkbootfs command not found while trying to build aosp kernel

Followed guide here: https://source.android.com/setup/build/building-kernels mkdir android-kernel && cd android-kernel repo init -u https://android.googlesource.com/kernel/manifest -b android-...
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1 vote
0 answers
113 views

pstore/ramoops won't work on Poco M3, rooted

I'm trying to use pstore logs on my Poco M3. I tried everything. PSTORE configs are activated on the kernel, pstore module is loaded on the phone, phone is rooted, /sys/fs/pstore is mounted ...
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1 vote
1 answer
3k views

How to edit root files in /sys (Permission Denied)?

I have been trying to change root files in my phone through an app I am developing. The phone I have is a Moto G6, fully rooted. I'm using terminal emulators to run commands on my phone. I've tried "...
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1 vote
0 answers
1k views

How to capture kernel panic logs when ROM failed to flash?

Background: Stuck in boot-loop when unpack and pack system.img? Short Description: I am trying to modify the system partition of my Samsung S10 5G system-as-root treble device. I have successfully ...
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1 vote
1 answer
306 views

Building Pixel 4a kernel [closed]

I'm trying to build my custom sunfish kernel on pixel 4a, note that the system is unlocked and rooted via "Magisk", After building success (for test I didn't change anything on kernel source)...
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1 vote
0 answers
323 views

What are the technical differences between bootloader, recovery, kernel and ROM? [duplicate]

Possible Duplicate: What is the difference between: Rooting, Jailbreak, ROM, Mod, etc.? I'd love a reference (or an explanation if anyone has the time) on what characterizes these different ...
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1 vote
1 answer
405 views

Modifications of vendor image on Android 10

There is a vendor image in my device I want to change (unpack/mount, doing changes, pack/umount). My purpose is to update boot.img with my new kernel (in rooted device). Unfortinatly it does not ...
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1 vote
1 answer
989 views

Building ROMs & Kernels?

I've been using customs ROMs and Kernels on my GS5 for a while now, but I want to get a clear explanation about how it works. Here are a few questions: What is 'building' in Android? I heard that the ...
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1 vote
1 answer
2k views

What is the default Kernel Governor in Stock Samsung Galaxy Mega Android ROM?

I have rooted my phone recently and just installed ROM Toolbox which has several Governors available. It is using OnDemand by default, but I switched to Interactive. I just need to be as close to ...
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  • 157
1 vote
0 answers
232 views

Why does android has only one zram but linux distros use many zram equal to the number of cpu cores?

Most android roms have only one zram device [zram0] but linux distros use many zram like zram0, zram1 .... Why is it like that? Does using many zram consumes more power or adds complexity? what's the ...
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0 votes
1 answer
1k views

Where is the current_now measurement generated

If you go into the adb shell, you can check what the amount of current the battery is discharging by using the following command cat /sys/class/power_supply/battery/current_now When the current is ...
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  • 151
0 votes
0 answers
824 views

USB OTG not showing WiFi network even after drivers are installed in Android kernel

I am trying to connect to WiFi using a USB WiFi stick by making use of OTG on my Android Nexus 6. The USB WiFi stick has a separate AP. However, I am unable to see this AP in the list of available ...
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  • 11
0 votes
2 answers
2k views

How do I get a version of Android with linux kernel >= 3.18 on a Nexus 5?

According to this post Android 7.1 has kernel 4.1.1 and Android 6.0 has kernel 3.18.10. I installed Android 6.0 on a Nexus 5 (using the latest google image) and ended up with kernel 3.4. Then I ...
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