EFI / UEFI

Загрузившись в EFI Shell мы можем найти требуемый диск командой

map -b

Если требуемый диск отображается, например, как fs9, то можно переключиться на него, выполнив

fs9:

Приглашение на следующей строке будет выглядеть как

fs9:\>

там уже пишем то, что хотим (из того, что есть): update.nsh или boot.nsh и т.п.

FreeBSD UEFI

Create Bootable UEFI-based USB with Windows

RHEL UEFI

RHEL GRUB & UEFI Boot

GRUB loads itself into memory in the following stages:

The UEFI-based platform reads the partition table on the system storage and mounts the EFI System Partition (ESP), a VFAT partition labeled with a particular globally unique identifier (GUID). The ESP contains EFI applications such as bootloaders and utility software, stored in directories specific to software vendors. Viewed from within the Red Hat Enterprise Linux 6.6 file system, the ESP is /boot/efi/, and EFI software provided by Red Hat is stored in /boot/efi/EFI/redhat/.

The /boot/efi/EFI/redhat/ directory contains grub.efi, a version of GRUB compiled for the EFI firmware architecture as an EFI application. In the simplest case, the EFI boot manager selects grub.efi as the default bootloader and reads it into memory.

If the ESP contains other EFI applications, the EFI boot manager might prompt you to select an application to run, rather than load grub.efi automatically.

GRUB determines which operating system or kernel to start, loads it into memory, and transfers control of the machine to that operating system.

Because each vendor maintains its own directory of applications in the ESP, chain loading is not normally necessary on UEFI-based systems. The EFI boot manager can load any of the operating system bootloaders that are present in the ESP.

GRUB contains several features that make it preferable to other boot loaders available for the x86 architecture. Below is a partial list of some of the more important features:

GRUB provides a true command-based, pre-OS environment on x86 machines. This feature affords the user maximum flexibility in loading operating systems with specified options or gathering information about the system. For years, many non-x86 architectures have employed pre-OS environments that allow system booting from a command line.

GRUB supports Logical Block Addressing (LBA) mode. LBA places the addressing conversion used to find files in the hard drive's firmware, and is used on many IDE and all SCSI hard devices. Before LBA, boot loaders could encounter the 1024-cylinder BIOS limitation, where the BIOS could not find a file after the 1024 cylinder head of the disk. LBA support allows GRUB to boot operating systems from partitions beyond the 1024-cylinder limit, so long as the system BIOS supports LBA mode. Most modern BIOS revisions support LBA mode.

GRUB can read ext2 partitions. This functionality allows GRUB to access its configuration file, /boot/grub/grub.conf, every time the system boots, eliminating the need for the user to write a new version of the first stage boot loader to the MBR when configuration changes are made. The only time a user needs to reinstall GRUB on the MBR is if the physical location of the /boot/ partition is moved on the disk. For details on installing GRUB to the MBR, refer to Section E.3, “Installing GRUB”.

Installing GRUB on UEFI Systems

The following procedure explains how to install or reinstall GRUB on a system using UEFI firmware. ⁠

Installing GRUB on BIOS-based Systems

Log in as root:

$ su -

Execute the grub-install command to install GRUB:

# grub2-install location

Replace location with the name of the drive or partition where you want to install the first stage of GRUB - for example, /dev/hda for the first hard drive on the system.

Optionally, you can open the /etc/default/grub configuration file, and edit existing boot options on the line starting with GRUB_CMDLINE_LINUX= to suit your needs. Note that this requires advanced knowledge of boot options, and is not necessary in most cases.

Generate the grub.conf configuration file, which will be used to construct the boot menu:

# grub-mkconfig -o /boot/grub/grub.conf

Log out from root:

# exit

The next time the system boots, the GRUB boot loader menu will appear before the kernel loads into memory.

efi_uefi/start.txt · Last modified: 2015/01/22 22:19 by rybario
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