Difference between revisions of "Linux Partition Table"
m |
m |
||
| Line 5: | Line 5: | ||
=== GPT === | === GPT === | ||
| + | For booting from a GPT device, Linux requires a BIOS Boot Partition and a boot loader that can work with the GPT format (such as Grub2). The boot manager will manage the boot entries in the persistent NVRAM. The appropriate boat loader is located on the UEFI system partition (ESP). | ||
| + | |||
Use the command 'gdisk' which is GPT fdisk to work with your GPT partition table. | Use the command 'gdisk' which is GPT fdisk to work with your GPT partition table. | ||
| Line 22: | Line 24: | ||
5 293GB 500GB 207GB ext4 /share | 5 293GB 500GB 207GB ext4 /share | ||
| − | The UEFI partition is marked with the boot flag. This is the first partition read on system boot. | + | The UEFI partition is marked with the boot flag. This is the first partition read on system boot. For UEFI to work, it has to be on the first partition at least 256MB large and bootable, the example above it is actually over sized by at least four times what is necessary. From there UEIF directs which partition to load next, or in this case, which one to direct to grub2. To access the UEFI setup we reboot the machine and from the grub2 menu select "System setup." |
| + | |||
| + | Also in the example above both / and /2 contain a grub bootloader. The UEFI directs to the one on / and does not see the one on /2 | ||
Q: When I have more than one partition with an active operating system, why does UEIF Startup Menu, Boot Menu (F9) only show one of the operating systems for UEFI Boot Sources? | Q: When I have more than one partition with an active operating system, why does UEIF Startup Menu, Boot Menu (F9) only show one of the operating systems for UEFI Boot Sources? | ||
| + | |||
| + | A: | ||
| + | |||
| + | efibootmgr is a utility under Linux for manipulating the UEFI boot manager such as changing the sequence of UEFI boot entries. | ||
| + | |||
| + | Tip: if UEFI Secure Boot is on, the machine will only boot to Windows and you must disable that in the BIOS to boot Linux. | ||
Revision as of 11:49, 30 August 2019
MBR (Master Boot Record) and GPT (GUID Partition Table) are two different types of partition table available to linux users now.
- MBR standards for Master Boot Record. It was introduced with IBM PC DOS 2.0 in 1983.
- GPT stands for GUID Partition Table. It is associated with UEFI
GPT
For booting from a GPT device, Linux requires a BIOS Boot Partition and a boot loader that can work with the GPT format (such as Grub2). The boot manager will manage the boot entries in the persistent NVRAM. The appropriate boat loader is located on the UEFI system partition (ESP).
Use the command 'gdisk' which is GPT fdisk to work with your GPT partition table.
More useful might be 'parted'. Here is example output:
(parted) print Model: ATA ST3500413AS (scsi) Disk /dev/sda: 500GB Sector size (logical/physical): 512B/512B Partition Table: gpt Disk Flags: Number Start End Size File system Name Flags 1 1049kB 1075MB 1074MB fat32 EFI System Partition boot, esp 2 1075MB 18.3GB 17.2GB linux-swap(v1) 3 18.3GB 156GB 137GB ext4 / 4 156GB 293GB 137GB ext4 /2 5 293GB 500GB 207GB ext4 /share
The UEFI partition is marked with the boot flag. This is the first partition read on system boot. For UEFI to work, it has to be on the first partition at least 256MB large and bootable, the example above it is actually over sized by at least four times what is necessary. From there UEIF directs which partition to load next, or in this case, which one to direct to grub2. To access the UEFI setup we reboot the machine and from the grub2 menu select "System setup."
Also in the example above both / and /2 contain a grub bootloader. The UEFI directs to the one on / and does not see the one on /2
Q: When I have more than one partition with an active operating system, why does UEIF Startup Menu, Boot Menu (F9) only show one of the operating systems for UEFI Boot Sources?
A:
efibootmgr is a utility under Linux for manipulating the UEFI boot manager such as changing the sequence of UEFI boot entries.
Tip: if UEFI Secure Boot is on, the machine will only boot to Windows and you must disable that in the BIOS to boot Linux.
