Where is Grub located?

[derBaer93]

Hey Forum,

im interessted in understanding how Grub Bootloader is started by the UEFI/BIOS.
I always thought Grub is installed on the EFI/MBR Partition created when installing a Linux System, but why is there a grubx64.efi file on linux systems under /boot/efi folder?Isnt this the Grub bootloader itself, which is supposed to be saved in the EFI Partition?

Thx in advance for your answers

 

[Aggam]

take this with a grain of salt, bc I'm not sure.
As far as I know, even if it is in another partition, it's simply mounted to that directory. You can mount storage mediums to specific directories.

 

[Peer]

Yeah, the boot files them selves are on the ESP (EFI system partition) that is (Normaly) mounted to /boot/efi
The grub config file (Normaly) is /boot/grub/grub.cfg and the file from which it is generated (using grub-mkconfig -o /boot/grub/grub.cfg) is /etc/default/grub. In this file are all relevant settings for the grub.

 

[captain-sensible]

you can look at whats on efi partition and "do" things using efibootmgr eg my output :

bash-5.0# efibootmgr
BootCurrent: 0003
Timeout: 0 seconds
BootOrder: 0003,0000,9999
Boot0000* Slackware	HD(1,GPT,192a9aa1-9848-4329-8171-9253ffc0f920,0x800,0x32000)/File(\EFI\Slackware\elilo.efi)
Boot0001* USB Drive (UEFI) - Hard Drive	BBS(HD,,0x0)..GO..NO........o.B.H.T. .W.R.2.0.2.I.0.0.6.4.G. .E.7.0.2.9.0.F.5......
...
Boot0003* slackware-14.2+	HD(1,GPT,192a9aa1-9848-4329-8171-9253ffc0f920,0x800,0x32000)/File(\EFI\slackware-14.2+\grubx64.efi)
Boot0004* USB Drive (UEFI) - Hard Drive	BBS(HD,,0x0)..GO..NO........o.B.H.T. .W.R.2.0.2.I.0.0.6.4.G. .E.7.0.2.9.0.F.5..................

theres an elilo entry elilo being efi version of lilo since i was using that as my boot manager then i installed grub2

the grub entry points to : EFI\slackware-14.2+\grubx64.efi

and this is what i have in boot:

bash-5.0$ tree -l 2 /boot/efi/EFI
2 [error opening dir]
/boot/efi/EFI
├── Slackware
│   ├── elilo.conf
│   ├── elilo.efi
│   ├── initrd.gz
│   ├── initrd_old.gz
│   └── vmlinuz
└── slackware-14.2+
    └── grubx64.efi

so there is the grub64.efi in slackware14+ == slackware current ( i did system upgrade from slackware 14.2 to current)


for uefi info this is not a bad starting point : http://www.rodsbooks.com/linux-uefi/

 

[Alexzee]

Grub is in the boot file of the root file system.

 

[f33dm3bits]

GNU GRUB - Wikipedia

en.wikipedia.org