doc: booti man-page

Provide a man-page for the booti command.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>

doc/usage/booti.rst

@@ -0,0 +1,114 @@
+.. SPDX-License-Identifier: GPL-2.0+:
+
+booti command
+=============
+
+Synopsis
+--------
+
+::
+
+    booti [<addr> [<initrd>[:<size>]] [<fdt>]]
+
+Description
+-----------
+
+The booti command is used to boot a Linux kernel in flat or compressed
+'Image' format. Which compressed formats are supported is configurable.
+
+addr
+    address of kernel image, defaults to CONFIG_SYS_LOAD_ADDR.
+
+initrd
+    address of the initial RAM disk. Use '-' to boot a kernel with a device
+    tree but without an initial RAM disk.
+
+size
+    size of the initial RAM disk. This parameter must be specified for raw
+    initial RAM disks.
+
+fdt
+    address of the device tree.
+
+To support compressed Image files the following environment variables must be
+set:
+
+kernel_comp_addr_r
+    start of memory area used for decompression
+
+kernel_comp_size
+    size of the compressed file. The value has to be at least the size of
+    loaded image for decompression to succeed. For the booti command the
+    maximum decompressed size is 10 times this value.
+
+Example
+-------
+
+This is the boot log of an Odroid C2 board:
+
+::
+
+    => load mmc 0:1 $fdt_addr_r dtb-5.10.0-3-arm64
+    27530 bytes read in 7 ms (3.7 MiB/s)
+    => load mmc 0:1 $kernel_addr_r vmlinuz-5.10.0-3-arm64
+    26990448 bytes read in 1175 ms (21.9 MiB/s)
+    => load mmc 0:1 $ramdisk_addr_r initrd.img-5.10.0-3-arm64
+    27421776 bytes read in 1209 ms (21.6 MiB/s)
+    => booti $kernel_addr_r $ramdisk_addr_r:$filesize $fdt_addr_r
+    Moving Image from 0x8080000 to 0x8200000, end=9c60000
+    ## Flattened Device Tree blob at 08008000
+       Booting using the fdt blob at 0x8008000
+       Loading Ramdisk to 7a52a000, end 7bf50c50 ... OK
+       Loading Device Tree to 000000007a520000, end 000000007a529b89 ... OK
+
+    Starting kernel ...
+
+The kernel can be compressed with gzip:
+
+.. code-block:: bash
+
+    cd /boot
+    gzip -k vmlinuz-5.10.0-3-arm64
+
+Here is the boot log for the compressed kernel:
+
+::
+
+    => setenv kernel_comp_addr_r 0x50000000
+    => setenv kernel_comp_size 0x04000000
+    => load mmc 0:1 $fdt_addr_r dtb-5.10.0-3-arm64
+    27530 bytes read in 6 ms (4.4 MiB/s)
+    => load mmc 0:1 $kernel_addr_r vmlinuz-5.10.0-3-arm64.gz
+    9267730 bytes read in 402 ms (22 MiB/s)
+    => load mmc 0:1 $ramdisk_addr_r initrd.img-5.10.0-3-arm64
+    27421776 bytes read in 1181 ms (22.1 MiB/s)
+    => booti $kernel_addr_r $ramdisk_addr_r:$filesize $fdt_addr_r
+       Uncompressing Kernel Image
+    Moving Image from 0x8080000 to 0x8200000, end=9c60000
+    ## Flattened Device Tree blob at 08008000
+       Booting using the fdt blob at 0x8008000
+       Loading Ramdisk to 7a52a000, end 7bf50c50 ... OK
+       Loading Device Tree to 000000007a520000, end 000000007a529b89 ... OK
+
+    Starting kernel ...
+
+Configuration
+-------------
+
+The booti command is only available if CONFIG_CMD_BOOTI=y.
+
+Which compression types are supported depends on:
+
+* CONFIG_BZIP2
+* CONFIG_GZIP
+* CONFIG_LZ4
+* CONFIG_LZMA
+* CONFIG_LZO
+* CONFIG_ZSTD
+
+Return value
+------------
+
+Normally this command does not return. If an error occurs, the return value $?
+is set to 1 (false). If the operating system returns to U-Boot, the system is
+reset.

doc/usage/index.rst

@@ -15,6 +15,7 @@ Shell commands
 
    base
    bootefi
+   booti
    bootmenu
    button
    conitrace