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32 .Nd Unified Extensible Firmware Interface bootstrapping procedures
36 Unified Extensible Firmware Interface provides boot- and run-time services
39 is a replacement for the legacy BIOS on the i386 and amd64 CPU architectures,
40 and is also used on arm, arm64 and ia64.
44 boot process loads system bootstrap code located in an EFI System Partition
46 The ESP is a GPT or MBR partition with a specific identifier that contains an
48 FAT file system with a specified file hierarchy.
49 .Bl -column -offset indent ".Sy Partition Scheme" ".Sy ESP Identifier"
50 .It Sy "Partition Scheme" Ta Sy "ESP Identifier"
51 .It GPT Ta C12A7328-F81F-11D2-BA4B-00A0C93EC93B
57 boot process proceeds as follows:
58 .Bl -enum -offset indent -compact
61 firmware runs at power up and searches for an OS loader in the EFI system
63 The path to the loader may be set by an EFI environment variable.
64 If not set, the default is
65 .Pa /EFI/BOOT/BOOTX64.EFI .
68 boot configuration for
73 .Pa /EFI/BOOT/BOOTX64.EFI .
76 reads boot configuration from
80 Unlike other first-stage boot loaders,
82 passes the configuration to the next stage boot loader and does not
83 itself act on the contents of the file.
86 searches partitions of type
92 The search begins with partitions on the device from which
94 was loaded, and continues with other available partitions.
99 partitions exist on the same device the
101 partition is preferred.
103 then loads and executes
107 loads and boots the kernel, as described in
113 system console is automatically selected when booting via
116 .Bl -tag -width /boot/loader -compact
117 .It Pa /boot/boot1.efi
121 .It Pa /boot/boot1.efifat
123 FAT file system image containing
131 .It Pa /boot/loader.efi
132 Final stage bootstrap
133 .It Pa /boot/kernel/kernel
135 .It Pa /boot/kernel.old/kernel
136 typical non-default kernel (optional)
147 boot support first appeared in
152 boot support was developed by
153 .An Benno Rice Aq Mt benno@FreeBSD.org ,
154 .An \&Ed Maste Aq Mt emaste@FreeBSD.org ,
156 .An Nathan Whitehorn Aq Mt nwhitehorn@FreeBSD.org .
159 Foundation sponsored portions of the work.
161 EFI environment variables are not supported by