Note in some file systems and file system configuration, you may need a 1.5 step file used to connect to the basic boot program and the second difference between the boot program.
For example, if the second step in the boot loader file is located in a first step in using a boot loader program cannot access the file system partition, you may want to indicate that the first step in a bootloader from 1.5 step file load additional instruction to read the second step the bootloader files. More related information, please refer to GRUB's information page. Previously mentioned boot method is called directly mount. Because this method is used in the directive directly loading the operating system, not to any bootloader and the operating system master file (such as kernel) intermediate code. However, different operating systems used by the boot process may be mentioned there are some subtle differences. For example, Microsoft DOS and Windows operating system at installation time, inclination tends to completely override the master boot record, instead of merging the current configuration of the master boot record. This will disrupt other operating system is stored in the master boot record of all information, such as RedHatLinux. Microsoft operating system, there are other proprietary operating system, use a technique called chain loading boot method to start. In this approach, the master boot record just simply point to the operating system partition of the first sector. GRUB support direct and chain loading boot method. GRUB cannot be used for almost all operating systems, the most popular file systems, as well as almost all of the system BIOS to recognition of the hard disk. GRUB GRUB contains many of the characteristics of properties, which makes GRUB than other available boot loader is more superior. Listed below are some of the more important features: · GRUB on the x 86 machine, provides a really based on the command line, before the operating system (pre-OS) environment. It is loads of options used to determine the operating system, or collect system information, provides the most flexibility. Many non-x 86 architecture is already in use before operating systems collar jing for many years, it provides the control system how to boot from a command line. When LILO or other x 86 boot loader uses some command properties, GRUB already contains many of the features in this regard. · GRUB supports logical block addressing (LBA). LBA is used to find the drive file address translation work on the drive hardware, it is used in many IDE and SCSI hard drives in all. Before using LBA, hard drives have a 1024 cylinder limit, i.e. BIOS cannot find in the 1024 cylinder files (such as a bootloader or kernel file). As long as the system BIOS to support LBA mode (most do), then LBA allows GRUB beyond 1024 cylinder limit boot OS. grub configuration · would each time the system boots is read. This avoids the user each time you change the boot option to override a master boot record. Most of the bootloader can be Waterloo Road to read configuration file, and use them to set the boot options. For example, the user must change a LILO's configuration file, and then run a command to the new configuration data is written back to the system's master boot record. This method than GRUB the approach it more dangerous, because an incorrect configuration of the master boot record will let the system will not boot. Using GRUB, if profile been misconfigured and boot, it will simply go to one of the default command line, allowing the user to manually enter the command to run the operating system. Apart from updating the system boot is the first step, a second step, or menu configuration file location, the master boot record will not be touched, but this is rare. Note: when GRUB configuration file is changed, there is no need to reboot GRUB. All changes can be automatically detected. If GRUB was restarted, the user will be returned to the command line grub shell. Install GRUB if RedHatLinux installation, GRUB is not installed, the following will explain how to install it, and it is set to the default boot loader. Note: if LILO is installed, and is the current system bootloader, and there is no need to use the GRUB and delete it. GRUB once after installation, will be the system default bootloader. First, get the latest GRUB package available. On RedHatLinux installation CD on the GRUB package can also be used. Secondly, at a shell prompt, run the command/sbin/grub-install, here is GRUB will be installed. For example:/sbin/grub-install/dev/da Finally, reboot the system. GRUB graphical bootloader menu appears. Second, the use of terminology in the GRUB GRUB before, one of the most important thing is to understand how this program is the reference device, such as system hard drives, partitions, etc. For Configuring GRUB to boot multiple operating systems, this information is very important. Device name of the system is the first hard disk drive (hd0) GRUB called. In the first partition is known as (hd0, 0), the second on the hard drive of the fifth partition called (hd1, 4). Usually when using GRUB, file system, it is customary to use the following naming: (,) in the device name in parentheses, and commas are very important. That is a hard disk (hd) or a floppy disk (fd) is specified. Is determined in accordance with the system BIOS and theDevice number, starting from 0. Basic IDE hard disk is marked as 0, second IDE hard disk is marked as 1. This sort is roughly equivalent to the linux kernel with the order of letters arranged device, just in a hda into 0, hdb in b variable to 1, and so on. Note: GRUB for device naming system is starting from 0, not 1. This is often the GRUB novices often make the most common errors. Refers to a hard disk on a partition number. Similar to the partition numbering starts from 0. Although most partitions can use numbers to specify, but if the system uses a BSD partition, then they still use letters to specify, such as a or c. GRUB in naming devices and partitions, use the following rules: · System use the IDE hard drive or SCSI hard drive, doesn't matter. All of the hard disk are hd begins. Beginning with the floppy disk fd. · When you specify the entire hard drive, regardless of its partitions, simply remove the comma and the partition number. When to tell GRUB configuration of a specific hard disk's master boot sector, this is important. For example, (hd0) specifies the first device, (hd3) specifies the fourth device. · If a system has multiple driver equipment, know the drive the BIOS determines the order is important. If the system only IDE or SCSI drives, it is quite simple. But if you have multiple drives are mixed, it becomes confusing. The file name when entering in the GRUB command includes the file, as in many operating systems use a menu list, file names must be directly on the device and after the specified partition. An absolute file name of the form: (,) when/path/to/ile most, users can partition the directory path with file name to the specified file. This approach is straightforward. In addition, we also will not appear in the file system to the file, such as GRUB in a partition is initially a few sectors in the chain the bootloader. In order to specify the files, you need to supply a chunk list (blocklist), from it to a piece to tell GRUB file location of the partition. When a file is composed of several different pieces together, you need to have a special way to write block list. Each file fragment position consists of a block of offset and starting from the offset point to describe the number of blocks, these fragments to a comma boundaries (comma-delimited) order together. Consider the following block list: 0 + 50,100 + 25,200 + 1 above the block list to tell GRUB uses a file, the file starting at the first partition, use the block 0 to 49 block, the block to 99, and article 124 block 199 block. When you use GRUB loading such as Microsoft Windows this way with chain loading of the operating system, you know how to write a block list is very useful. If you start from 0 blocks, then you can omit the offset of the block. As an example, when the chain in the first loading the file on your hard drive first partition, you can use the following naming: (hd0, 0) + 1 following a similar block list name chainloader command. It is set to the correct device and partition as root after the GRUB command line. Chainloader + 1 GRUB's root file system for some users often confuse the root file system in GRUB (rootfilesystem) usage of the term. GRUB's root file system and Linux root file system is not related, this needs in mind. GRUB's root file system is used for a particular device's root partition. GRUB uses this information to hang in (mount) this device and load file from it. On RedHatLinux, once the GRUB to load its own contains Linux kernel root partition, then the kernel command can set the kernel file location as an option. Once the Linux kernel boot, it set up its own root file system, the root file system is the one most people use to contact with Linux. The original GRUB root file system, and it's linked-in is removed, they only exist in the file used to boot the kernel. On the root and the kernel command for more information, refer to the following commands section.
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