ARM development steps: After reading this, the development ideas will be clearer

Let's make a rough comparison between the well-known MS DOS and Linux booting parts. In MS DOS, the boot program located in the boot sector on the disk is responsible for loading IO.SYS into memory, and IO.SYS is responsible for loading the DOS kernel --MSDOS.SYS into memory. In Linux, the bootsect program located in the boot sector is responsible for loading setup and the Linux kernel into memory, and then handing control to setup. Driver In the Linux system, the set of entry points provided by the device driver is described to the system by a structure. The entry points provided by the device driver are registered with the system when the device driver is initialized so that the system can call them at the appropriate time. In the Linux system, the character device driver is registered with the system by calling register_chrdev. In Linux, in addition to directly modifying the source code of the system kernel and adding the device driver to the kernel, the device driver can also be used as a loadable module, and the system administrator can dynamically load it to make it part of the kernel. The system administrator can also dynamically unload the loaded module. In Linux, modules can be written in C language and compiled into target files using gcc (without linking, existing as *.o files).

To do this, you need to add the -c parameter to the gcc command line. After successfully registering the device driver with the system (after successfully calling register_chrdev), you can use the mknod command to map the device to a special file. When other programs use this device, they only need to operate on this special file. Replace X-Window with MicroWindows MicroWindows uses a layered design method. It allows different layers to be changed to adapt to actual applications.

At the bottom layer, drivers for the screen, mouse/touch screen, and keyboard are provided, allowing programs to access actual hardware devices and other user-defined devices.

In the middle layer, there is a lightweight graphics engine that provides methods for drawing lines, area filling, drawing polygons, clipping, and using color models.

At the top level, different APIs are provided for graphical applications to use. These APIs may or may not provide desktop and window appearance. Currently, MicroWindows supports Windows Win32/WinCE GDI and Nano-X APIs. These APIs provide close compatibility between Win32 and X Window System, making it easy to port other applications to MicroWindows.