I. The operating system startup principle on the UEFI motherboard draws a rough picture without any text descriptions.
Ii. Installation Practice record 2.1 physical environment Machine Type: desktop machine model: Lenovo thinkcenter m4350t machine features: pre-installed Windows 8, the motherboard supports UEFI and secure boot, hard disk 500 GB, using GPT partition. This motherboard is compatible with the legacy BIOS (legacy boot) boot and can be set using the BIOS option. Centos supports both bios and UEFI, so there are two installation methods. 2.2 traditional BIOS installation method (1) set BIOS: Enable CSM, disable secure boot; (2) use diskgen or similar tools to format the hard disk into MBR format; (3) download the CentOS-6.4-x86_64-minimal.iso official website, and burn into a cd; (4) from the CD start, step by step installation. After the installation is complete, centos boot process: Boot Process: BIOS ---- hard disk MBR (With grub part) ---------- other parts of grub (may be located at the beginning of a partition) ------- load and start centos. Note: in fact, it is difficult for other parts of grub to survive. You must find enough sectors to store yourself, it cannot be the same as the sector used by the File System (because grub has very few code and cannot identify the file system, it can only find other parts by the physical sector, the physical sector occupied by files in the file system may change, so the remaining part of grub cannot be stored in the file system !!! 2.3 UEFI Modern installation method (1) BIOS: Disable CSM, disable secure startup; (2) use diskgen or similar tools to the hard disk format GPT format (you can create more than 4 primary partition); (3) the official website to download the CentOS-6.3-x86_64-minimal-EFI.iso, and burn into a cd; (currently, the 6.4 version of the EFI image has not been released.) (Correction: centos images later than 6.4 support both bios and UEFI. The EFI version is no longer released separately. We have a special discussion on this issue, see http://bugs.centos.org/view.php? Id = 5387 ). (4) Start and install the system from the CD. During installation, an ESP partition must be created and mounted to/boot/EFI. Other operations are the same as traditional installation. Note: After the installation is complete,/EFI/redflag/grub. EFI in the ESP partition is started by default. After the system starts, you can run the efiboogmgr command to view and modify the UEFI Startup menu. However, my own experiment proves that the modified menu does not take effect. Another way to change the Startup File is to change the grub. change the name of EFI so that UEFI cannot find this file. When the menu item is invalid,/EFI/boot/bootx64.efi is automatically started. This is just an agreed file name. You can rename any desired Startup File. My approach is to refind. change the name of EFI to bootx64.efi, so that refind can be started by default, and the bootmanger refind can automatically scan all the FAT32 partitions. the EFI file is listed in the graphic interface for the user to choose to start. Centos startup process after installation in this way: Boot Process: BIOS ------ grub. EFI program in the hard disk ESP partition ------- load and start centos. Note: This method provides a dedicated partition for the start loader grub, making grub very comfortable and bulky, and there is no need to divide it into multiple parts, this is grub. EFI. Three installation methods: the traditional BIOS + MBR or UEFI + GPT installation of centos depends on the use environment. In my experiment environment, which method can be used easily with a GB hard disk? If the hard disk is larger than 2 TB, UEFI + GPT is required. From the perspective of technological development, UEFI + GPT is a trend, so my personal attitude is: if the motherboard and OS support, try to use UEFI + GPT to install OS!
