First and foremost thing, go to your BIOS and trun on/select booting from UEFI option.
Booting Linux from UEFI environment as well creating the environment. This is an attempt to let you familier with the UEFI booting requirement for Linux.
Few basic things first, Please create a FAT formatted EFI partition .
Then, please create a efi directory in /boot directory then mount the EFI partition on it .
To make it more consistent, please put an entry in /etc/fstab like this :
UUID="83BB-469F" /boot/efi vfat umask=0077 0 1
OR
/dev/EFI_Partition /boot/efi vfat umask=0077 0 1
Please change the "EFI_Partiton" to actual partition number , that might /dev/sda1 or /dev/sda2
The .conf files for the specific OS has to reside in the /boot/efi/loader/entries directory and it looks like this :
ArchLinux.conf Debian.conf Gentoo.conf Opensuse.conf Slackware.conf Tools.conf UEFI-shell.conf
There is also a "loader" directory under /boot/efi/ , which consist a file called "loader.conf"
timeout 5
default Gentoo
console-mode keep
This is bare minimal. You can replace the OS of your choice in the default entry, so , the cursor will always place on it.
Here is how the EFI folder content looks like , which reside in /boot/efi/ ...basically holding the kernel and initrd images
ArchLinux Boot debian Gentoo goofiboot opensuse.nsh Shell.efi slackware.nsh tools
archlinux.nsh certs debian.nsh gentoo.nsh opensuse refind slackware
Now if I entered any of those OS directory , the content will be like this :
initramfs-ArchLinux-5.8.14.img vmlinuz-ArchLinux-5.8.14
So, basically if the building mechanism of kernel not putting the kernel image and initrd image in the specific direcotry in EFI(I believe modern distros does put in) , then you have to manually put those two files in that specific(OS dir) under EFI folder.
Install "efibootmgr" package/software in your computer to see the thing about UEFI stuff from command line , and also to create boot entry in the UEFI directory.
Here is how it look like , when you fire the "efibootmgr" from cli with the -v option:
efibootmgr -v
BootCurrent: 0013
Timeout: 0 seconds
BootOrder: 0013,0016,0014,0015,0009,0004,0007,0008,000A,000B,000C,0012
Boot0000 Setup FvFile(721c8b66-426c-4e86-8e99-3457c46ab0b9)
Boot0001 Boot Menu FvFile(126a762d-5758-4fca-8531-201a7f57f850)
Boot0002 Diagnostic Splash Screen FvFile(a7d8d9a6-6ab0-4aeb-ad9d-163e59a7a380)
Boot0003 Lenovo Diagnostics FvFile(3f7e615b-0d45-4f80-88dc-26b234958560)
Boot0004 Startup Interrupt Menu FvFile(f46ee6f4-4785-43a3-923d-7f786c3c8479)
Boot0005 Rescue and Recovery FvFile(665d3f60-ad3e-4cad-8e26-db46eee9f1b5)
Boot0006 MEBx Hot Key FvFile(ac6fd56a-3d41-4efd-a1b9-870293811a28)
Boot0007* USB CD VenMsg(bc7838d2-0f82-4d60-8316-c068ee79d25b,86701296aa5a7848b66cd49dd3ba6a55)
Boot0008* USB FDD VenMsg(bc7838d2-0f82-4d60-8316-c068ee79d25b,6ff015a28830b543a8b8641009461e49)
Boot0009* ATA HDD0 VenMsg(bc7838d2-0f82-4d60-8316-c068ee79d25b,91af625956449f41a7b91f4f892ab0f600)
Boot000A* ATA HDD1 VenMsg(bc7838d2-0f82-4d60-8316-c068ee79d25b,91af625956449f41a7b91f4f892ab0f601)
Boot000B* ATA HDD2 VenMsg(bc7838d2-0f82-4d60-8316-c068ee79d25b,91af625956449f41a7b91f4f892ab0f602)
Boot000C* USB HDD VenMsg(bc7838d2-0f82-4d60-8316-c068ee79d25b,33e821aaaf33bc4789bd419f88c50803)
Boot000D* PCI LAN VenMsg(bc7838d2-0f82-4d60-8316-c068ee79d25b,78a84aaf2b2afc4ea79cf5cc8f3d3803)
Boot000E* IDER BOOT CDROM PciRoot(0x0)/Pci(0x16,0x2)/Ata(0,1,0)
Boot000F* IDER BOOT Floppy PciRoot(0x0)/Pci(0x16,0x2)/Ata(0,0,0)
Boot0010* ATA HDD VenMsg(bc7838d2-0f82-4d60-8316-c068ee79d25b,91af625956449f41a7b91f4f892ab0f6)
Boot0011* ATAPI CD VenMsg(bc7838d2-0f82-4d60-8316-c068ee79d25b,aea2090adfde214e8b3a5e471856a354)
Boot0012* PCI LAN VenMsg(bc7838d2-0f82-4d60-8316-c068ee79d25b,78a84aaf2b2afc4ea79cf5cc8f3d3803)
Boot0013* Linux Boot Manager HD(3,GPT,0c5344f1-db24-4668-aef2-9f007e93caac,0x3ff4a800,0x200000)/File(\EFI\goofiboot\goofibootx64.efi)
Boot0014* elilo HD(3,GPT,0c5344f1-db24-4668-aef2-9f007e93caac,0x3ff4a800,0x200000)/File(\EFI\Boot\elilo-x86_64.efi)
Boot0015* EFIBoot HD(3,GPT,0c5344f1-db24-4668-aef2-9f007e93caac,0x3ff4a800,0x200000)/File(\EFI\Boot\BOOTX64.EFI)
Boot0016* rEFInd Boot Manager HD(3,GPT,0c5344f1-db24-4668-aef2-9f007e93caac,0x3ff4a800,0x200000)/File(\EFI\refind\refind_x64.efi)
efibootmgr -c -d /dev/sda -p 1 -L "Arch Linux" -l '\EFI\arch\vmlinuz-arch.efi' -u root=/dev/sda3 ro initrd=EFI/arch/initramfs-arch.img
Change the disk and partition as per your requirement.
grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=gentoo --recheck --no-floppy --debug
