More accurately, Grub is a way to edit boot files like bcdedit. bcdedit and grub can be used to edit and manage boot files on their respective systems whether it is a Legacy or EFI install. efibootmgr is limited to managing the EFI booting.

BCD (and the many bcd commands) is part of the new vista boot rewrite to support uefi. BCD isn't in any way a loader. Grub and it's configuration is a loader. eifbootmgr you are correct is a boot manager for efi in linux.

To manage uefi one may need this in windows. https://docs.microsoft.com/en-us/win...options-in-efihttps://neosmart.net/wiki/easybcd/uefi/

This only shows 2 SATA drives. There are 2 PCIe drives with Windows that are not showing.


# parted -l
Model: ATA Samsung SSD 850 (scsi)
Disk /dev/sda: 1000GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags:

Number Start End Size File system Name Flags
1 1049kB 316MB 315MB fat32 EFI system partition boot, esp
2 316MB 450MB 134MB Microsoft reserved partition msftres
3 450MB 913GB 913GB Basic data partition msftdata


Model: ATA Samsung SSD 860 (scsi)
Disk /dev/sdb: 1000GB
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 2149MB 1074MB ext4
3 2149MB 902GB 900GB lvm




What I don't understand is just the two SATA disks are shown by parted -l and the other two PCIe disks are now shown. Parted -l shows one data disks (not a boot disk) and the Linux disk. The two Windows disks are missing.

Maybe this visual diagram will help with understanding which disks are involved. Windows is a dead-end, when I fire up bcdedit, it doesn't even show the Linux option at all. So I must use grub2 and represent these 3 disks there as 3 different boot options.

# efibootmgr
BootCurrent: 0001
Timeout: 1 seconds
BootOrder: 0000,000E,000B,000F,0001,0011,0006
Boot0000* Windows Boot Manager
Boot0001* Fedora
Boot0006 Windows Boot Manager
Boot000B* Windows Boot Manager
Boot000E* Windows Boot Manager
Boot000F* Windows Boot Manager
Boot0011* UEFI OS

I got Fedora 29 reinstalled on the new 1TB SSD. Again, I while I can multiboot Windows 10 (primary) and Windows 10 (backup), there is no option showing up in BIOS (that is, UEFI that shows you the Linux boot option, it appears to be impossible to configure.

In Windows, the Linux SSD is not even showing up with a letter and it's impossible to assign a drive letter to it as the option is grayed out (In Windows 10)

So I booted back in Linux.

Therefore forget bcdedit, how do I configure grub2 to multiboot Win10, Win10 and Fedora?

Am I correct in understanding that grub2 modifies UEFI options just like bcdedit? When I reboot the machine, by default it goes into the first SSD as defined by bcdedit which is Windows 10. The bootloader grub2 is located on the Linux SSD but how do I activate it if I am not hitting that SSD at all during the boot process - I Have to hit the F11 button and then select Fedora from the list of bootable devices?

grub2-mkconfig -o /boot/grub2/grub.cfg

I ran that and it created the output file.