1.. SPDX-License-Identifier: GPL-2.0+:
2
3booti command
4=============
5
6Synopsis
7--------
8
9::
10
11    booti [<addr> [<initrd>[:<size>]] [<fdt>]]
12
13Description
14-----------
15
16The booti command is used to boot a Linux kernel in flat or compressed
17'Image' format. Which compressed formats are supported is configurable.
18
19addr
20    address of kernel image, defaults to CONFIG_SYS_LOAD_ADDR.
21
22initrd
23    address of the initial RAM disk. Use '-' to boot a kernel with a device
24    tree but without an initial RAM disk.
25
26size
27    size of the initial RAM disk. This parameter must be specified for raw
28    initial RAM disks.
29
30fdt
31    address of the device tree.
32
33To support compressed Image files the following environment variables must be
34set:
35
36kernel_comp_addr_r
37    start of memory area used for decompression
38
39kernel_comp_size
40    size of the compressed file. The value has to be at least the size of
41    loaded image for decompression to succeed. For the booti command the
42    maximum decompressed size is 10 times this value.
43
44Example
45-------
46
47This is the boot log of an Odroid C2 board:
48
49::
50
51    => load mmc 0:1 $fdt_addr_r dtb-5.10.0-3-arm64
52    27530 bytes read in 7 ms (3.7 MiB/s)
53    => load mmc 0:1 $kernel_addr_r vmlinuz-5.10.0-3-arm64
54    26990448 bytes read in 1175 ms (21.9 MiB/s)
55    => load mmc 0:1 $ramdisk_addr_r initrd.img-5.10.0-3-arm64
56    27421776 bytes read in 1209 ms (21.6 MiB/s)
57    => booti $kernel_addr_r $ramdisk_addr_r:$filesize $fdt_addr_r
58    Moving Image from 0x8080000 to 0x8200000, end=9c60000
59    ## Flattened Device Tree blob at 08008000
60       Booting using the fdt blob at 0x8008000
61       Loading Ramdisk to 7a52a000, end 7bf50c50 ... OK
62       Loading Device Tree to 000000007a520000, end 000000007a529b89 ... OK
63
64    Starting kernel ...
65
66The kernel can be compressed with gzip:
67
68.. code-block:: bash
69
70    cd /boot
71    gzip -k vmlinuz-5.10.0-3-arm64
72
73Here is the boot log for the compressed kernel:
74
75::
76
77    => setenv kernel_comp_addr_r 0x50000000
78    => setenv kernel_comp_size 0x04000000
79    => load mmc 0:1 $fdt_addr_r dtb-5.10.0-3-arm64
80    27530 bytes read in 6 ms (4.4 MiB/s)
81    => load mmc 0:1 $kernel_addr_r vmlinuz-5.10.0-3-arm64.gz
82    9267730 bytes read in 402 ms (22 MiB/s)
83    => load mmc 0:1 $ramdisk_addr_r initrd.img-5.10.0-3-arm64
84    27421776 bytes read in 1181 ms (22.1 MiB/s)
85    => booti $kernel_addr_r $ramdisk_addr_r:$filesize $fdt_addr_r
86       Uncompressing Kernel Image
87    Moving Image from 0x8080000 to 0x8200000, end=9c60000
88    ## Flattened Device Tree blob at 08008000
89       Booting using the fdt blob at 0x8008000
90       Loading Ramdisk to 7a52a000, end 7bf50c50 ... OK
91       Loading Device Tree to 000000007a520000, end 000000007a529b89 ... OK
92
93    Starting kernel ...
94
95Configuration
96-------------
97
98The booti command is only available if CONFIG_CMD_BOOTI=y.
99
100Which compression types are supported depends on:
101
102* CONFIG_BZIP2
103* CONFIG_GZIP
104* CONFIG_LZ4
105* CONFIG_LZMA
106* CONFIG_LZO
107* CONFIG_ZSTD
108
109Return value
110------------
111
112Normally this command does not return. If an error occurs, the return value $?
113is set to 1 (false). If the operating system returns to U-Boot, the system is
114reset.
115