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UEFI(8)                 FreeBSD System Manager's Manual                UEFI(8)

     UEFI - Unified Extensible Firmware Interface bootstrapping procedures

     The UEFI Unified Extensible Firmware Interface provides boot- and run-
     time services to operating systems.  UEFI is a replacement for the legacy
     BIOS on the i386 and amd64 CPU architectures, and is also used on arm64
     and ia64.

     The UEFI boot process loads system bootstrap code located in an EFI
     System Partition (ESP).  The ESP is a GPT or MBR partition with a
     specific identifier that contains an msdosfs(5) FAT file system with a
     specified file hierarchy.

           Partition Scheme        ESP Identifier
           GPT                     C12A7328-F81F-11D2-BA4B-00A0C93EC93B
           MBR                     0xEF

     The UEFI boot process proceeds as follows:
           1.   UEFI firmware runs at power up and searches for an OS loader
                in the EFI system partition.  The path to the loader may be
                set by an EFI environment variable.  If not set, the default
                is /EFI/BOOT/BOOTX64.EFI.  The default UEFI boot configuration
                for FreeBSD installs boot1.efi as /EFI/BOOT/BOOTX64.EFI.
           2.   boot1.efi reads boot configuration from /boot.config or
                /boot/config.  Unlike other first-stage boot loaders,
                boot1.efi passes the configuration to the next stage boot
                loader and does not itself act on the contents of the file.
           3.   boot1.efi searches partitions of type freebsd-ufs and
                freebsd-zfs for loader.efi.  The search begins with partitions
                on the device from which boot1.efi was loaded, and continues
                with other available partitions.  If both freebsd-ufs and
                freebsd-zfs partitions exist on the same device the
                freebsd-zfs partition is preferred.  boot1.efi then loads and
                executes loader.efi.
           4.   loader.efi loads and boots the kernel, as described in

     The vt(4) system console is automatically selected when booting via UEFI.

                   First stage UEFI bootstrap
                   msdosfs(5) FAT file system image containing boot1.efi for
                   use by bsdinstall(8) and the bootcode argument to gpart(8).
                   Final stage bootstrap
                   default kernel
                   typical non-default kernel (optional)

     vt(4), boot.config(5), msdosfs(5), boot(8), gpart(8), uefisign(8)

     UEFI boot support first appeared in FreeBSD 10.1.

     UEFI boot support was developed by Benno Rice <[email protected]>, Ed
     Maste <[email protected]>, and Nathan Whitehorn
     <[email protected]>.  The FreeBSD Foundation sponsored portions of
     the work.

     EFI environment variables are not supported by loader(8) or the kernel.

FreeBSD 11.1-RELEASE-p4        February 11, 2016       FreeBSD 11.1-RELEASE-p4
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