The UEFI specification has a standard convention that each vendor should place the bootloader for a permanently installed OS within the path \EFI\ on the ESP, so having multiple UEFI bootloaders co-exist on the same ESP is actually supported and should make things easier than with classic BIOS that had a single Master Boot Record per disk. In Ubuntu, these UEFI NVRAM boot settings can be viewed using the sudo efibootmgr -v command in Windows, you can start a Command Prompt as Administrator and then use the bcdedit /enum firmware command to view the settings. The descriptive name is simply "ubuntu" and the optional data is not used. The optional data seems to contain a GUID reference to something within the Windows bootloader's BCD configuration file.įor Ubuntu, the pathname should be \EFI\Ubuntu\grub圆4.efi if you don't need Secure Boot support, or \EFI\Ubuntu\shim圆4.efi if the Secure Boot shim is used. optionally, some data for the bootloaderįor Windows, the standard UEFI pathname for the Windows boot process will be \EFI\Microsoft\Boot\bootmgfw.efi, and the descriptive name will be "Windows Boot Manager".a descriptive (human-friendly) name for this particular bootloader instance.Bootloader pathname on the EFI System Partition (ESP) that holds the bootloader(s).When installing the bootloader, four things are written to the NVRAM memory that holds the firmware settings: When an operating system is installed permanently to a UEFI system, there is one new step that absolutely did not exist on classic BIOS. Bootloader path for a permanently installed OS If you want to create a Secure Boot-compatible USB stick for UEFI, you should place a copy of the shim as EFI\boot\boot圆4.efi and a copy of GRUB as EFI\boot\grub圆4.efi, as the shim bootloader will look for grub圆4.efi in the same directory the shim bootloader is in. If you want, you can use grub-install -removable to tell it to install to the fallback boot path, or grub-install -force-extra-removable to overwrite any existing bootloader in the fallback path and replace it with GRUB. Windows will install a copy of its bootloader to this path automatically when installing GRUB, the grub-install (or grub2-install depending on Linux distribution) command may also put a copy of the respective bootloader here if it does not already exist. This is the only bootloader pathname that the UEFI firmware on 64-bit X86 systems will look for without any pre-existing NVRAM boot settings, so this is what you want to use on removable media. EFI\boot\boot圆4.efi: Fallback bootloader path
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