Embedded Linux | What are BootLoader, Linux Kernel, and File System?

What is a BootLoader?

It is a boot program, which is the first program to execute after hardware reset. Its main job is to initialize the environment for the operating system to run, such as memory, timers, buffers, etc. Once this is done, it loads the operating system’s code into memory, and then the operating system can start and execute. At this point, the task of the bootloader is complete.

Types of bootloaders include U-BOOT, REDBOOT, LILO, etc. My development board uses Uboot.

What is the Kernel?

The Kernel is the core of Linux, meaning it is the code of the Linux operating system itself. When U-BOOT finishes booting, it loads the Linux kernel into memory and jumps to the Kernel to execute.

What is a file system?

The Linux kernel must mount a file system at the end of its startup. This is a characteristic of Linux; it is different from other operating systems. For example, QT, Android, and Ubuntu systems all have the Linux kernel at their core, but their file systems are different.

For example, Uboot, Kernel, and file system are compiled into three separate files,

which means three files will be generated, and we need to learn how to flash these files onto the board.

What is an application program?

It runs on top of the operating system, utilizing the resources of the operating system to function, representing the final business logic. For example, on Windows, there are many application programs, such as QQ, WPS, WORD, EXCEL, and various other applications.

Linux drivers

Linux drivers include three types: character devices, block devices, and network devices.

06 Embedded Experts

Basic digital circuits + C language + basic framework knowledge —–> Embedded driver engineer
Data structures + compilation principles ——> Senior embedded driver engineer
Computer system architecture + operating systems (from abstract to concrete) ——-> System architect engineer

07 Learning Path08 Environment Setup

Virtual machine installation and Linux operating system tutorial

Linux | Linux disk management

Qt | Complete tutorial for installing Qt 6.5.3 on Ubuntu 20.04 and creating an app (involves many development details, use with caution for commercial purposes)

ubuntu + MobaXterm + ssh + running Qt

The download link for Ubuntu is:

https://www.ubuntu.com/download/desktop

When installing Ubuntu, be sure to choose a relatively large drive letter,

If your computer has only 8 GB, then you can set it to half, which is 4GB.

Then set the processor; since the author’s computer is quad-core, I set it to 4, and we generally set the number of processor cores to 1.

09 What are Bridge Mode, NAT Mode, and Host-Only Mode?

Bridge Mode is like connecting the virtual machine and the host computer to the same local area network, where all computers can access the virtual machine (SSH can connect multiple times), and the virtual machine can also access all computers in this local area network. Later, when we use the nfs function, we must use bridge mode; other modes will not work, so selecting bridge mode here is fine.
NAT Mode is like placing the virtual machine and the host computer in the same local area network,

but other hosts in this network cannot access our virtual machine.
Host-Only Mode is like our virtual machine is an independent machine, unrelated to any machine in this local area network, and of course, it is also unrelated to our host; we generally do not use this.

USB controller, for compatibility, we set it to 3.0. The last one is the display; uncheck “Accelerate 3D graphics”. After setting, click “OK” to complete the hardware settings of the virtual machine.

Set the resolution Displays