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authorAlexander Graf <agraf@suse.de>2016-03-04 01:10:09 +0100
committerTom Rini <trini@konsulko.com>2016-03-15 21:30:12 -0400
commit996a18a7142442767821f4c8bb560cb081d6948f (patch)
treec19465b8930641afebef1f4ef515093b4b09069f /doc
parent74522c898b35e641cde9ea6a20625a3d80e56e53 (diff)
downloadtalos-obmc-uboot-996a18a7142442767821f4c8bb560cb081d6948f.tar.gz
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efi_loader: Add README section in README.efi
To preserve all cover letter knowledge of the status on UEFI payload support, let's add some sections to README.efi. Signed-off-by: Alexander Graf <agraf@suse.de> v3 -> v4: - Add section about config options - s/10kb/10KB/
Diffstat (limited to 'doc')
-rw-r--r--doc/README.efi83
1 files changed, 82 insertions, 1 deletions
diff --git a/doc/README.efi b/doc/README.efi
index 23a3cdd57a..1fd3f004c3 100644
--- a/doc/README.efi
+++ b/doc/README.efi
@@ -4,6 +4,28 @@
# SPDX-License-Identifier: GPL-2.0+
#
+=========== Table of Contents ===========
+
+ 1 U-Boot on EFI
+ 1.1 In God's Name, Why?
+ 1.2 Status
+ 1.3 Build Instructions
+ 1.4 Trying it out
+ 1.5 Inner workings
+ 1.6 EFI Application
+ 1.7 EFI Payload
+ 1.8 Tables
+ 1.9 Interrupts
+ 1.10 32/64-bit
+ 1.11 Future work
+ 1.12 Where is the code?
+
+ 2 EFI on U-Boot
+ 2.1 In God's Name, Why?
+ 2.2 How do I get it?
+ 2.3 Status
+ 2.4 Future work
+
U-Boot on EFI
=============
This document provides information about U-Boot running on top of EFI, either
@@ -234,7 +256,6 @@ board/efi/efi-x86/efi.c
common/cmd_efi.c
the 'efi' command
-
--
Ben Stoltz, Simon Glass
Google, Inc
@@ -242,3 +263,63 @@ July 2015
[1] http://www.qemu.org
[2] http://www.tianocore.org/ovmf/
+
+-------------------------------------------------------------------------------
+
+EFI on U-Boot
+=============
+
+In addition to support for running U-Boot as a UEFI application, U-Boot itself
+can also expose the UEFI interfaces and thus allow UEFI payloads to run under
+it.
+
+In God's Name, Why?
+-------------------
+
+With this support in place, you can run any UEFI payload (such as the Linux
+kernel, grub2 or gummiboot) on U-Boot. This dramatically simplifies boot loader
+configuration, as U-Boot based systems now look and feel (almost) the same way
+as TianoCore based systems.
+
+How do I get it?
+----------------
+
+EFI support for 32bit ARM and AArch64 is already included in U-Boot. All you
+need to do is enable
+
+ CONFIG_CMD_BOOTEFI=y
+ CONFIG_EFI_LOADER=y
+
+in your .config file and you will automatically get a bootefi command to run
+an efi application as well as snippet in the default distro boot script that
+scans for removable media efi binaries as fallback.
+
+Status
+------
+
+I am successfully able to run grub2 and Linux EFI binaries with this code on
+ARMv7 as well as AArch64 systems.
+
+When enabled, the resulting U-Boot binary only grows by ~10KB, so it's very
+light weight.
+
+All storage devices are directly accessible from the uEFI payload
+
+Removable media booting (search for /efi/boot/boota{a64,arm}.efi) is supported.
+
+Simple use cases like "Plug this SD card into my ARM device and it just
+boots into grub which boots into Linux", work very well.
+
+Future work
+-----------
+
+Of course, there are still a few things one could do on top:
+
+ - Improve disk media detection (don't scan, use what information we
+have)
+ - Add EFI variable support using NVRAM
+ - Add GFX support
+ - Make EFI Shell work
+ - Network device support
+ - Support for payload exit
+ - Payload Watchdog support
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