Linux system Boot 01-Basic concepts

I. Description of the start-up phase

Linux launches are broadly divided into 6 phases: (http://www.thegeekstuff.com/2011/02/linux-boot-process/)

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Second, the BIOS boot process

1. Basic Process

1) The BIOS will give control to the bootloader (stage1) of the hard drive.

2) bootloader (stage1) loads the stage1_5 into memory.

3) bootloader through stage1.5, identify the file system and load the stage2 into memory.

4) Stage2 can now load the Menu.lst configuration file in the file system and enter the boot process of the boot kernel.

2.BIOS and related chips

The role of BIOS:

The BIOS is responsible for communicating with all hardware when the computer is started and presenting the computer in front of the user.

BIOS with South/North Bridge:

North Bridge mainly controls memory and CPU, while South Bridge is mainly responsible for all peripheral equipment such as PCI,PCI-E,USB,VGA.

There is a special area in the South Bridge that is responsible for storing CMOS information, and CMOS is where the user stores the BIOS device.

III. structure diagram of MBR

1.MBR Total 512 bytes.

2.446 bytes Store Bootloader's stage1.

3.64 bytes as 4 partitions of information, each partition accounted for 16 bytes.

4. The last two bytes are the checksum of the MBR area.

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Four, disk partition structure diagram

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One storage device has only one MBR (Master Boot Record), and each partition has a boot sector extension partition without boot sector. MBR to Partition1 has 64 sectors (512 bytes) of =64*512byte=32k.

The launcher can be installed in the MBR and boot sector, following the relationship between the MBR and boot sector in the context of the Linux System and window coexistence:

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The Bootloder is installed in 1.MBR and provides a menu that can be directly directed to Linux.

2. The bootloader that points to Windows is installed in partition 1.

3. Partition 2 installs a bootloader that points to Linux.

Attention:

If you install Windows after installing Linux, Windows installs two copies of Bootloader in the MBR and the bootsector of its own partition, and Linux cannot find it.

If you install Windows first install Linux, then Linux will install its own bootloder in the MBR, at this time we can modify the MBR configuration, provide access to the window is a menu.

Reference blog:

http://blog.csdn.net/sdcxyz/article/details/23601491

http://www.thegeekstuff.com/2011/02/linux-boot-process/

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Linux system Boot 01-Basic concepts