1 ==============================================
2 The Unified Extensible Firmware Interface (UEF
3 ==============================================
4
5 UEFI, the Unified Extensible Firmware Interfac
6 governing the behaviours of compatible firmwar
7 maintained by the UEFI Forum - http://www.uefi
8
9 UEFI is an evolution of its predecessor 'EFI',
10 UEFI are used somewhat interchangeably in this
11 source code. As a rule, anything new uses 'UEF
12 to legacy code or specifications.
13
14 UEFI support in Linux
15 =====================
16 Booting on a platform with firmware compliant
17 makes it possible for the kernel to support ad
18
19 - UEFI Runtime Services
20 - Retrieving various configuration information
21 interface of UEFI configuration tables. (ACP
22
23 For actually enabling [U]EFI support, enable:
24
25 - CONFIG_EFI=y
26 - CONFIG_EFIVAR_FS=y or m
27
28 The implementation depends on receiving inform
29 in a Flattened Device Tree (FDT) - so is only
30
31 UEFI stub
32 =========
33 The "stub" is a feature that extends the Image
34 PE/COFF executable, including a loader applica
35 load the kernel directly from the UEFI shell,
36 lightweight bootloaders like Gummiboot or rEFI
37
38 The kernel image built with stub support remai
39 booting in non-UEFI environments.
40
41 UEFI kernel support on ARM
42 ==========================
43 UEFI kernel support on the ARM architectures (
44 when boot is performed through the stub.
45
46 When booting in UEFI mode, the stub deletes an
47 Instead, the kernel reads the UEFI memory map.
48
49 The stub populates the FDT /chosen node with (
50 following parameters:
51
52 ========================== ====== =========
53 Name Type Descripti
54 ========================== ====== =========
55 linux,uefi-system-table 64-bit Physical
56
57 linux,uefi-mmap-start 64-bit Physical
58 populated
59
60 linux,uefi-mmap-size 32-bit Size in b
61 pointed t
62
63 linux,uefi-mmap-desc-size 32-bit Size in b
64 memory ma
65
66 linux,uefi-mmap-desc-ver 32-bit Version o
67
68 kaslr-seed 64-bit Entropy u
69 base addr
70
71 bootargs String Kernel co
72 ========================== ====== =========
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