doc: uefi.rst: Document launching UEFI binaries from FIT images
This patch adds a new section "Launching a UEFI binary from a FIT image"
documenting the usage of the CONFIG_BOOTM_EFI extension to bootm command
that offers a verified boot alternative for UEFI binaries such as GRUB2.
Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@gmail.com>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/doc/uefi/uefi.rst b/doc/uefi/uefi.rst
index db942df..a8fd886 100644
--- a/doc/uefi/uefi.rst
+++ b/doc/uefi/uefi.rst
@@ -63,6 +63,40 @@
table. The Linux kernel EFI stub uses the load options as command line
arguments.
+Launching a UEFI binary from a FIT image
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+A signed FIT image can be used to securely boot a UEFI image via the
+bootm command. This feature is available if U-Boot is configured with::
+
+ CONFIG_BOOTM_EFI=y
+
+A sample configuration is provided as file doc/uImage.FIT/uefi.its.
+
+Below you find the output of an example session starting GRUB::
+
+ => load mmc 0:1 ${kernel_addr_r} image.fit
+ 4620426 bytes read in 83 ms (53.1 MiB/s)
+ => bootm ${kernel_addr_r}#config-grub-nofdt
+ ## Loading kernel from FIT Image at 40400000 ...
+ Using 'config-grub-nofdt' configuration
+ Verifying Hash Integrity ... sha256,rsa2048:dev+ OK
+ Trying 'efi-grub' kernel subimage
+ Description: GRUB EFI Firmware
+ Created: 2019-11-20 8:18:16 UTC
+ Type: Kernel Image (no loading done)
+ Compression: uncompressed
+ Data Start: 0x404000d0
+ Data Size: 450560 Bytes = 440 KiB
+ Hash algo: sha256
+ Hash value: 4dbee00021112df618f58b3f7cf5e1595533d543094064b9ce991e8b054a9eec
+ Verifying Hash Integrity ... sha256+ OK
+ XIP Kernel Image (no loading done)
+ ## Transferring control to EFI (at address 404000d0) ...
+ Welcome to GRUB!
+
+See doc/uImage.FIT/howto.txt for an introduction to FIT images.
+
Executing the boot manager
~~~~~~~~~~~~~~~~~~~~~~~~~~