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Linux version in AOSP
Android Version |API Level |Linux Version in AOSP |Header Version
----------------------------------------------------------------------------------------
1.5 Cupcake |3 |(2.6.27) |
1.6 Donut |4 |(2.6.29) ...
24
Kernels vary from manufacturer to manufacturer. A lot of those kernels come from the pure stock kernel line of sources found on CAF, what these manufacturers do is take those stock sources, modify them to suit based on the board/chipset used, also, implement their own drivers.
Take a good look around you, there's variations of touchscreens, variations of ...
17
The Linux user IDs that Android uses to isolate apps from each other are completely unrelated to user profiles on Android 4.2 tablets.
In Android, each app gets its own directory for saving data. The Linux user ID system is used to make sure apps can't read each others' data. But all these data directories are inside one directory on the filesystem, /data/...
14
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 users, each part of a set of groups. These groups are used to manage which users are allowed access to what. For example, in Linux you could set up all printer ...
13
The PC architecture is built around commodity parts because it started out as clones of a specific product, the IBM PC, that were specifically designed to be compatible with it, and therefore with each other. Generally speaking, you could take a program or peripheral device from one PC-compatible and put it into another, and expect it to work. That ability ...
8
Yes, it is possible to install custom kernels on stock roms. The kernel developer will usually say which roms (or types of roms) the kernel supports. If you are not sure you can try reading the kernel thread, and there will always be poeple saying things like "working great on [firmware version here]". This way you can also make sure that it will work ok on ...
8
The filesystem support is device-specific, and in fact many devices using Android 2.3 support ext3 in the kernel (or ext4, which can also mount ext3 and ext2 filesystems).
Usually the difference in filesystem support is due to different hardware. Older devices often used raw NAND flash chips and MTD drivers in Linux, which did not support conventional ...
8
The kernel on your device is tied heavily to the version of the Android operating system you're running. Sony releases your phone with the "stock ROM" (think a "stock" car in stock car racing; no customization, just as-is from the factory), including the stock kernel. Normally, your kernel would be updated when the operating system - your "ROM" - is updated. ...
7
Yes you're correct. Android will use CPU frequency as required including deep sleep to highest CPU frequency. If Android uses 1.2Ghz for high end task it will consume more battery but on the other hand will finish the task quicker than 1Ghz.
Many custom ROM also allows you to change this CPU scaling behavior by changing the governor. For eg: if you choose ...
7
There are perfectly good reasons why those informations are readable, and that's nothing dangerous (writing, however, would be). This is inherited from the Linux system Android builds upon -- and I will give you a few short examples to show you the good of it:
If you list contents of the /proc (virtual) directory, you will find things like e.g.:
/proc/...
7
The differences change from version to version (both of Linux and of Android), and the exact kernel is different for each device. A kernel for Android is a mainstream Linux kernel, with additional drivers for the specific device, and other additional functionality, such as enhanced power management or faster graphics support.
Many features in the Android ...
7
On Nexus devices, at least: CF Auto-Root works by unlocking the device's boot loader via fastboot (if it isn't already unlocked), then sending the device a custom boot image (kernel and ramdisk) that it should run instead of booting from the built-in system or recovery partition. It's analogous to booting your PC from a CD or USB drive instead of from the ...
7
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 create a new OS for smartphones. Smartphones (and earlier, PDAs) based on not only the Linux kernel but the GNU userspace, with the same programming environment as ...
6
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% Energy Aware Scheduling (kernel/sched)
13.8% Networking (net/netfilter)
13.5% Sdcardfs (fs/sdcardfs)
9.4% USB (drivers/usb)
7.2% SoC (arch/arm64, arch/x86)
6.2% f2fs ...
6
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 greater than the partition. That's all.
If the kernel is not good for the ROM, your device would not boot into the ROM or would cause some other instability, so ...
6
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 software and hardware, among other things, and the kernel needs to be just right. If the device hard-bricks, a USB jig would need to be used to force the device into ...
6
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 powerful as you'd like to think), and sometimes illegal when dealing with proprietary components.
6
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 fastboot device it is usually pretty easy - search the internet for instructions for your specific device.
You will need a TWRP recovery image for your device, but ...
6
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 image is invalid or cannot be booted into, the boot process automatically falls back to the image in the boot partition. Once the temporary kernel is booted into, ...
5
The reason is because Android's Linux kernel are generally not compiled on Android itself, instead it had to be cross compiled from another computer. This causes various issues, because the device configuration are not available on compile time, and it is not feasible to compile a generic kernel with all drivers due to space limitation (whereas most desktop ...
5
Beside the device specific differences and wake lock that Dan Hulme and Lie Ryan mentions, Android removed System V IPC features (message queues, shared memory segments, semaphores) that could lead to resource leaks (http://www.kandroid.org/ndk/docs/system/libc/SYSV-IPC.html). This probably is just a matter of configuring the kernel build. Also the Android ...
5
It stands for git, the name of the version control system used for the Linux kernel. Git itself isn't an abbreviation, it's just the name of the system. The git describe command is what's used to generate these version identifiers, and its manpage describes the format:
The hash suffix is "-g" + 7-char
abbreviation for the tip commit of parent ... ...
5
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 (CONFIG_ANDROID_PERSISTENT_RAM) to handle a block of RAM that wasn't erased across reboots (2).
persistent_ram was based on Linux upstream RAMOOPS code which ...
4
The files
/proc/<pid>/maps
/proc/<pid>/smaps
are NOT universally readable by anyone, at least not in stock device.
Try running from a Terminal Emulator from inside Android (running as a regular user), instead of ADB (which runs at a slightly elevated privilege). ADB runs with a lot of privileges because it's used for debugging and need to be ...
4
You can verify by checking /proc/config.gz and search through it looking for the configure option - CONFIG_BLK_DEV_LOOP=y.
To do that you need to do it this way:
cp /proc/config.gz /sdcard/kernel_config.gz
and
adb pull /sdcard/kernel_config.gz
Unzip the kernel_config.gz and open it up in a notepad or text editor and search it.
If its either # ...
4
TL;DR version:
Unlocking the bootloader
The initial program when you boot is the bootloader. If "locked" it may: 1) block attempts at flashing 2) refuse to boot the phone if something unauthorized was flashed. Unlocking it means changing a setting that affects this behaviour.
Rooting
see what does rooting a phone mean
Jailbreaking
iphone word for ...
4
This question is already well answered, but one thing I find most non-tech people getting confused about is the difference between rooting/jailbreaking and SIM Unlocking.
This is the simple explanation I use for non-tech people.
A smartphone is essentially 2 things
A phone
Unlocking is relevant to the phone part of the smartphone.
In some countries ...
4
Well.... drivers and the kernel are not exactly the same.
Drivers are what control the cell antenna, wifi, bluetooth, etc. These are proprietary drivers because the manufacturer has to create a way (the drivers) to talk to their hardware.
The kernel is an intermediary level between the OS/application and the actual drivers (or cpu or memory or any other ...
4
Go to Settings -> About phone menu and scroll all the way to the bottom:
Tap the "SELinux status" menu 3 times in a row in a quick succession. This will bring up a prompt asking you to confirm enabling the other modes:
Be aware that currently this feature is still under heavy development, and isn't supported on all devices yet.
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