Article directory
The three major management permissions of the Android system
1. Software permissions
The user software reads and writes the camera, positioning, Bluetooth, and system files, etc.
2. User permissions
Set a mobile phone password, restart the mobile phone, uninstall and install third-party software, etc. These operations cannot be done by ordinary software, so the user's authority is higher than that of third-party software.
Three, root user (ROOT) permissions
Super user permissions, with this kind of permissions, you can completely control the mobile phone, to realize some closed functions of the mobile phone system itself, such as modifying the mobile phone model, uninstalling the system software, realizing the control of the underlying hardware, scheduling CPU and GPU, etc.
Partitions for Android
Boot partition
Contains the Kernel (kernel) and Ramdisk (virtual memory) of the operating system. Many operations to change the CPU scheduling involve the Boot partition. If the Boot partition is erased or damaged, the phone will not start normally, and it will usually open in the first boot partition. One screen (called Kami by many people) is the LOGO interface of major manufacturers. Once erased, the device can only be reinstalled with a new boot partition, which can be achieved by installing a ROM containing the boot partition, otherwise the Android system cannot be started
Recovery Partition
As the name suggests, this is a recovery partition, which can be used to restore and update the contents of other partitions. Students who have installed the Windows system should know PE. This is like a very simple operating system. Other partitions are erased and restarted. Many flashing operations are performed in this partition. Android uses more TWRP. However, since the introduction of the new OTA A/B System Updates after Android 7.0, there have been many inappropriate A phone with a Recovery partition. A/B System Updates is an upgrade method that turns the Boot partition and the System partition into two sets, that is, the AB partition. Usually, A (primary partition) is used, and B is generally a backup partition.
Advantages of using AB partition:
1. Using this AB partition scheme can achieve a seamless upgrade of the Android system , and users can use the mobile phone while upgrading the system in the background. The system is upgraded in the backup partition. After the upgrade is completed and the phone is restarted, the backup partition will automatically switch to the primary partition. 2. To
prevent the upgrade failure from causing the machine to freeze, when the current system cannot be started, it will switch back to the original system partition
Disadvantages:
1. The system partition space is doubled , and one of the two partitions of AB will always be used as a spare partition.
So there is a new solution, virtual AB (VAB) . The current Android mobile phone comes with Android 11 system, and Android 11 mobile phones generally adopt this new VAB partition method, which solves the problem of double occupied space. question.
Flashing the AB partition and VAB partition is more troublesome than the ordinary Recovery partition flashing, because in the AB partition and VAB partition, the Recovery partition is merged into the Boot partition, and it is more troublesome to flash a third-party Recovery. of.
Cache partition cache
The cache area of the Android system, the cache can help users quickly open the most frequently accessed data and applications in the system without reloading. /b> Erasing this partition will not affect personal user data. After erasing, the content of the cache will continue to be updated in subsequent uses.
System partition
As the name suggests, this is a system partition, which contains the entire operating system and pre-installed software . System upgrades and flashing are usually operated on this partition. If the System partition is damaged, it will be stuck on the second screen of the card machine, and the animation interface of booting will not be able to enter the system.
Vendor partition
Contains some application and library files customized by developers. Many manufacturers will put these files in the System partition to facilitate later update and maintenance.
Data partition
The data partition includes all kinds of data, music, video, pictures, various software, file information, system setting records, etc. stored by the user in the mobile phone. Erasing this partition is equivalent to clearing all software data, which is equivalent to mobile phone recovery. Factory settings. But this partition will not affect the normal startup of the system.
Two brushing methods
Before flashing, you need to unlock the BL lock, BootLoader, and boot loader, which are equivalent to the BIOS on the PC motherboard. If Recovery is compared to PE, then BL is equivalent to BIOS/UEFI.
The boot process of Android phones:
BL—>Android kernel (Kernel)—>fastboot—>mobile operating system.
Wire Brush - FastBoot
You need to download the ADB tool, the link is as follows:
ADB tool official website
First, open the developer options of the mobile phone, enable USB debugging, then connect the computer to the mobile phone, and enter the fastboot of the mobile phone.
To be continued...
Card brush——Recovery
Card swiping generally uses the third-party Recovery, and TWRP is used more often. TWRP official website links the mobile phone to enter fastboot, and executes the flashing command:
fastboot flash recovery 镜像名称.img
To be continued...