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| author | Heinrich Schuchardt <xypron.glpk@gmx.de> | 2020-08-16 13:27:19 +0300 |
|---|---|---|
| committer | Heinrich Schuchardt <xypron.glpk@gmx.de> | 2020-08-24 17:37:53 +0300 |
| commit | ebcbfc7d6de20b094090da3aa3b944cfd8103baa (patch) | |
| tree | b9baa768a04a3d1224294a77fcf031ab5db46f49 /doc | |
| parent | dd12c6a4463ff62271a783772b92571dab3b56fb (diff) | |
| download | u-boot-ebcbfc7d6de20b094090da3aa3b944cfd8103baa.tar.xz | |
doc: update UEFI documentation
* UEFI variables can be persisted
* describe that the sequence of files loaded before bootefi matters
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/uefi/uefi.rst | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/doc/uefi/uefi.rst b/doc/uefi/uefi.rst index a72e729cc8..728f7bf4e0 100644 --- a/doc/uefi/uefi.rst +++ b/doc/uefi/uefi.rst @@ -59,6 +59,10 @@ Below you find the output of an example session starting GRUB:: 120832 bytes read in 7 ms (16.5 MiB/s) => bootefi ${kernel_addr_r} ${fdt_addr_r} +The bootefi command uses the device, the file name, and the file size +(environment variable 'filesize') of the most recently loaded file when setting +up the binary for execution. So the UEFI binary should be loaded last. + The environment variable 'bootargs' is passed as load options in the UEFI system table. The Linux kernel EFI stub uses the load options as command line arguments. @@ -217,13 +221,13 @@ which has to be enabled via CONFIG_SUPPORT_EMMC_RPMB=y. Executing the boot manager ~~~~~~~~~~~~~~~~~~~~~~~~~~ -The UEFI specification foresees to define boot entries and boot sequence via UEFI -variables. Booting according to these variables is possible via:: +The UEFI specification foresees to define boot entries and boot sequence via +UEFI variables. Booting according to these variables is possible via:: bootefi bootmgr [fdt address] -As of U-Boot v2018.03 UEFI variables are not persisted and cannot be set at -runtime. +As of U-Boot v2020.10 UEFI variables cannot be set at runtime. The U-Boot +command 'efidebug' can be used to set the variables. Executing the built in hello world application ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |