hboot and recovery, boot.img, system.img

hboot

The role of HBOOT

The mobile phone is booted by hboot. Here is a brief description of the process. After hboot starts, it will check the status of the security lock:

If it is found to be S-ON after inspection, it means that the security lock is open, then hboot will write-protect the system and recovery partitions while completing the boot.

If it is found to be S-OFF after checking, it means that the security lock is turned off, then hboot will open the write protection of the system and recovery partitions while completing the boot.

What does this modified hboot do here?

When the mobile phone is started through hboot, when hboot checks the state of the security lock, no matter what the check result is, the modified hboot will think that the security lock is closed, that is, let hboot deceive itself that the security lock is inS-OFF state.In fact, the safety lock at this time is still S-ON, but it is displayed as S-OFF.

This also finds a reasonable explanation for the following situation:

Friends whose machine status is ENG S-OFF flashed the official package, then ENG changed back to SHIP, and S-OFF changed back to S-ON.But friends whose machine status is SHIP S-OFF will do the same operation without losing S-OFF.

Because the official package is a complete flashing package, the hboot will be overwritten during the update process. Then, when the modified hboot is replaced with the official original hboot, our machine will return to the original one.SHIP status.At this time, because ENG S-OFF is an illusion, S-OFF changes back to S-ON, but because SHIP S-OFF really turns off the safety lock, S-OFF remains unchanged..

hboot is equivalent to the computer's bios

recovery

Recovery is the Android phone backup function, which refers to a mode that can modify the data or system inside the Android phone (similar to windows PE or DOS).In this mode, the existing system can be backed up or upgraded, and the factory settings can also be restored here.
If you flash the third-party Recovery, you will get more functions, and you can flash the third-party rom, but not the official one.

boot.img

boot.img and system.img are the partition image files that are often used when flashing the machine

boot.img is a file that must be loaded to start the Android system.Simply put, boot.img contains two parts, kernel and ramdisk.
Kernel Operating System Kernel The operating system kernel refers to the core part of most Linux operating systems.It consists of those parts of the operating system that manage memory, files, peripherals, and system resources.The operating system kernel typically runs processes and provides inter-process communication.
A virtual memory disk is a technology used by software to simulate a portion of memory (RAM) as a hard disk.Compared with direct hard disk file access, this technology can greatly improve the speed of file access on it.But the volatile nature of RAM also means that this part of the data will be lost when the power is turned off.In general, however, the data transferred to the RAM disk is a copy of a file that is permanently stored on the hard disk or elsewhere.With proper configuration, the virtual disk can be re-created when the system is restarted.

boot.img will guide the system to start, if the wrong boot.img is flashed during the flashing process, the system will not be able to start normally

system.img

system.img is an image file that stores system files in the Android system. The file format is yaff2 or emmc. When flashing, expand it and flash it into the system partition of the phone. system.imgdirectory structure:

app directory: store general apk files.bin directory: stores some Linux tools, but most of them are links to toolbox.etc directory: Store system configuration files.fonts directory: store the font files of the system.framework directory: store all jar packages and resource file packages of the system platform.lib directory: The shared library of the system is stored.media directory: Store multimedia resources of the system, mainly ringtones.priv-app directory: The newly added directory from android4.4 to store the core apk files of the system.tts directory: store the language synthesis files of the system.usr directory: store various keyboard layouts, time zone files.vendor directory: store configuration files, firmware, and dynamic libraries of some third-party vendors.xbin directory: store system management tools, this folder is equivalent to sbin in the standard Linux file system.build.prop file: The definition file of system properties.