BIOS and EFI introduction and their startup CD making

Many of the installation discs now meet the boot requirements of both the EFI platform and the BIOS platform, and in this article, learn how to make bootable discs that meet both the Legacy BIOS platform and the EFI platform boot. You will learn:

Legacy BIOS overview, Introduction to the startup process, and start-up CD steps to make the Legacy BIOS platform;

EFI overview, Introduction to Startup process, and the production of EFI platform to start the CD steps;

Make a boot CD step that meets both the Legacy BIOS platform and the EFI platform.

Legacy BIOS Boot Introduction and CD-ROM production

Legacy BIOS Boot Introduction

First look at how the Legacy BIOS boots or boots. When the system first boots, or the system is reset, the processor executes a code at a known location. This location is in the basic input/output system (BIOS) and is stored in the flash memory on the motherboard. The CPU invokes the reset vector to start a program at a known address in the Flash/rom. Typically, it performs a boot self-test (POST) to check the machine. Finally, it loads the first sector from the Master boot Record (MBR) on the boot drive.

The first phase of the boot loader begins. The Boot program boot loader is located in the first sector of the MBR. The boot loader is now loaded into RAM and executed. This boot loader is less than 512 bytes (a sector) in size, and its effect is to load the second stage boot loader.

When the second phase of the boot loader is loaded into RAM and executes, an animated screen is typically displayed, and Linux and an optional initial RAM disk (the temporary root file system) are loaded into memory. When the image is loaded, the second phase of the boot loader gives control to the kernel image, and the kernel can be decompressed and initialized. During this phase, the second phase of the boot loader detects the system hardware, enumerates the http://www.aliyun.com/zixun/aggregation/11585.html of the system's links "> hardware devices, mounts the root devices, and then loads the necessary kernel modules." After these actions are completed, the first User space program (INIT) is started and the advanced system initialization is performed.

Figure 1. Boot process schematic

To create a support Legacy BIOS boot CD

Step one: Prepare Isolinux.bin and working directory

Add a subdirectory, such as isolinux/, to a directory that is ready to be ISO, and then put the isolinux.cfg and a bootable media isolinux.bin for all the discs, isolinux the corresponding kernel, INITRD And so on, the directory structure is as follows:

Listing 1. MYBIOSISO directory Structure

Step Two: Configure Isolinux.cfg

Listing 2. Configure Isolinux.cfg