projects / people / ms / u-boot.git / blame
| Commit | Line | Data |
|---|---|---|
| 1aa5e936 SG |
1 | # |
| 2 | # Copyright (C) 2015 Google, Inc | |
| 3 | # | |
| 4 | # SPDX-License-Identifier: GPL-2.0+ | |
| 5 | # | |
| 6 | ||
| f3b5056c | 7 | EFI on U-Boot |
| 1aa5e936 | 8 | ============= |
| f3b5056c HS |
9 | This document provides information about the implementation of the UEFI API [1] |
| 10 | in U-Boot. | |
| 1aa5e936 | 11 | |
| 1aa5e936 | 12 | |
| f3b5056c | 13 | =========== Table of Contents =========== |
| 1aa5e936 | 14 | |
| f3b5056c HS |
15 | Motivation |
| 16 | How do I get it? | |
| 1aa5e936 | 17 | Status |
| 1aa5e936 | 18 | Future work |
| 1aa5e936 | 19 | |
| 1aa5e936 | 20 | |
| f3b5056c HS |
21 | Motivation |
| 22 | ---------- | |
| 996a18a7 | 23 | |
| f3b5056c | 24 | With this API support in place, you can run any UEFI payload (such as the Linux |
| 996a18a7 AG |
25 | kernel, grub2 or gummiboot) on U-Boot. This dramatically simplifies boot loader |
| 26 | configuration, as U-Boot based systems now look and feel (almost) the same way | |
| 27 | as TianoCore based systems. | |
| 28 | ||
| 29 | How do I get it? | |
| 30 | ---------------- | |
| 31 | ||
| 32 | EFI support for 32bit ARM and AArch64 is already included in U-Boot. All you | |
| 33 | need to do is enable | |
| 34 | ||
| 35 | CONFIG_CMD_BOOTEFI=y | |
| 36 | CONFIG_EFI_LOADER=y | |
| 37 | ||
| 38 | in your .config file and you will automatically get a bootefi command to run | |
| 39 | an efi application as well as snippet in the default distro boot script that | |
| 40 | scans for removable media efi binaries as fallback. | |
| 41 | ||
| 42 | Status | |
| 43 | ------ | |
| 44 | ||
| 45 | I am successfully able to run grub2 and Linux EFI binaries with this code on | |
| 46 | ARMv7 as well as AArch64 systems. | |
| 47 | ||
| 48 | When enabled, the resulting U-Boot binary only grows by ~10KB, so it's very | |
| 49 | light weight. | |
| 50 | ||
| 51 | All storage devices are directly accessible from the uEFI payload | |
| 52 | ||
| 53 | Removable media booting (search for /efi/boot/boota{a64,arm}.efi) is supported. | |
| 54 | ||
| 55 | Simple use cases like "Plug this SD card into my ARM device and it just | |
| 56 | boots into grub which boots into Linux", work very well. | |
| 57 | ||
| c7ae3dfd SG |
58 | |
| 59 | Running HelloWord.efi | |
| 60 | --------------------- | |
| 61 | ||
| 62 | You can run a simple 'hello world' EFI program in U-Boot. | |
| 63 | Enable the option CONFIG_CMD_BOOTEFI_HELLO. | |
| 64 | ||
| 65 | Then you can boot into U-Boot and type: | |
| 66 | ||
| 67 | > bootefi hello | |
| 68 | ||
| 69 | The 'hello world EFI' program will then run, print a message and exit. | |
| 70 | ||
| 71 | ||
| 996a18a7 AG |
72 | Future work |
| 73 | ----------- | |
| 74 | ||
| 75 | Of course, there are still a few things one could do on top: | |
| 76 | ||
| 77 | - Improve disk media detection (don't scan, use what information we | |
| 78 | have) | |
| 79 | - Add EFI variable support using NVRAM | |
| 80 | - Add GFX support | |
| 81 | - Make EFI Shell work | |
| 82 | - Network device support | |
| 83 | - Support for payload exit | |
| 84 | - Payload Watchdog support | |
| f3b5056c HS |
85 | |
| 86 | [1] http://uefi.org/ |