Difference between revisions of "Talk:Linux Partition Table"
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EFI-mode booting from GPT -- Under EFI, booting is handled by boot loaders stored on the EFI System Partition (ESP), which shows up in GParted as having the "boot flag" set. The ESP is normally mounted at /boot/efi in Ubuntu, and Ubuntu's GRUB goes in the ESP's EFI/ubuntu directory -- that is, /boot/efi/EFI/ubuntu. The computer knows which boot loader to launch because of NVRAM entries, which you can examine and manipulate with the efibootmgr command in Ubuntu. Type sudo efibootmgr to see the existing entries, or add -v to see extended information. You can use -c to add new entries, -B to delete entries, -o to change the boot priority, and so on. (Some of these options require additional options to do any good.) Type man efibootmgr for details. Note that EFI boot loaders are ordinary files; they have no components that are stored "raw" in the MBR or partition boot sector, unlike BIOS boot loaders. EFI-mode GRUB still relies on files in the Linux /boot directory tree, though, just like its BIOS-mode counterpart. | EFI-mode booting from GPT -- Under EFI, booting is handled by boot loaders stored on the EFI System Partition (ESP), which shows up in GParted as having the "boot flag" set. The ESP is normally mounted at /boot/efi in Ubuntu, and Ubuntu's GRUB goes in the ESP's EFI/ubuntu directory -- that is, /boot/efi/EFI/ubuntu. The computer knows which boot loader to launch because of NVRAM entries, which you can examine and manipulate with the efibootmgr command in Ubuntu. Type sudo efibootmgr to see the existing entries, or add -v to see extended information. You can use -c to add new entries, -B to delete entries, -o to change the boot priority, and so on. (Some of these options require additional options to do any good.) Type man efibootmgr for details. Note that EFI boot loaders are ordinary files; they have no components that are stored "raw" in the MBR or partition boot sector, unlike BIOS boot loaders. EFI-mode GRUB still relies on files in the Linux /boot directory tree, though, just like its BIOS-mode counterpart. | ||
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| + | == Please select boot device: == | ||
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| + | Please select boot device: | ||
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| + | UEFI Boot Sources | ||
| + | ubuntu | ||
| + | Legacy Boot Sources | ||
| + | Hard Drive | ||
| + | SATA0 | ||
| + | Network Controller (IBA GE Slot 00C8 v1550) | ||
Latest revision as of 12:07, 30 August 2019
EFI-mode booting from GPT
# efibootmgr BootCurrent: 0000 Timeout: 0 seconds BootOrder: 0000,0001,0002,0003,0004,0005,0006,0007 Boot0000* ubuntu Boot0001 DTO UEFI USB Floppy/CD Boot0002* DTO UEFI USB Hard Drive Boot0003 DTO UEFI ATAPI CD-ROM Drive Boot0004 CD/DVD Drive Boot0005* DTO Legacy USB Floppy/CD Boot0006* Hard Drive Boot0007* IBA GE Slot 00C8 v1550
BIOS-mode booting from GPT -- On a BIOS-based computer or an EFI-based computer that uses its Compatibility Support Module (CSM) to emulate a BIOS, GRUB is installed split across the Master Boot Record (MBR; the first sector of the disk), the BIOS Boot Partition, and files in the Linux /boot directory. In some cases, the BIOS Boot Partition code can be placed elsewhere, but Ubuntu pretty much insists on the BIOS Boot Partition being present. Since you don't have this partition on your disk (it shows up as having the "bios_grub flag" set in GParted), it's pretty clear that your disk is not set up for BIOS-mode booting.
EFI-mode booting from GPT -- Under EFI, booting is handled by boot loaders stored on the EFI System Partition (ESP), which shows up in GParted as having the "boot flag" set. The ESP is normally mounted at /boot/efi in Ubuntu, and Ubuntu's GRUB goes in the ESP's EFI/ubuntu directory -- that is, /boot/efi/EFI/ubuntu. The computer knows which boot loader to launch because of NVRAM entries, which you can examine and manipulate with the efibootmgr command in Ubuntu. Type sudo efibootmgr to see the existing entries, or add -v to see extended information. You can use -c to add new entries, -B to delete entries, -o to change the boot priority, and so on. (Some of these options require additional options to do any good.) Type man efibootmgr for details. Note that EFI boot loaders are ordinary files; they have no components that are stored "raw" in the MBR or partition boot sector, unlike BIOS boot loaders. EFI-mode GRUB still relies on files in the Linux /boot directory tree, though, just like its BIOS-mode counterpart.
Please select boot device:
Please select boot device:
UEFI Boot Sources
ubuntu
Legacy Boot Sources
Hard Drive
SATA0
Network Controller (IBA GE Slot 00C8 v1550)
