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bootm command

Synopsis

bootm [fit_addr]#<conf>[#extra-conf]
bootm [[fit_addr]:<os_subimg>] [[<fit_addr2>]:<rd_subimg2>] [[<fit_addr3>]:<fdt_subimg>]

bootm <addr1> [[<addr2> [<addr3>]]    # Legacy boot

Description

The bootm command is used to boot an Operating System. It has a large number of options depending on what needs to be booted.

Note that the second form supports the first and/or second arguments to be omitted by using a hyphen '-' instead.

fit_addr / fit_addr2 / fit_addr3
address of FIT to boot, defaults to CONFIG_SYS_LOAD_ADDR. See notes below.
conf
configuration unit to boot (must be preceded by hash '#')
extra-conf
extra configuration to boot. This is supported only for additional devicetree overlays to apply on the base device tree supplied by the first configuration unit.
os_subimg
OS sub-image to boot (must be preceded by colon ':')
rd_subimg
ramdisk sub-image to boot. Use a hyphen '-' if there is no ramdisk but an FDT is needed.
fdt_subimg
FDT sub-image to boot

See below for legacy boot. Booting using :doc:`../fit/index` is recommended.

Note on current image address

When bootm is called without arguments, the image at current image address is booted. The current image address is the address set most recently by a load command, etc, and is by default equal to CONFIG_SYS_LOAD_ADDR. For example, consider the following commands:

tftp 200000 /tftpboot/kernel
bootm
# Last command is equivalent to:
# bootm 200000

As shown above, with FIT the address portion of any argument can be omitted. If <addr3> is omitted, then it is assumed that image at <addr2> should be used. Similarly, when <addr2> is omitted, it is assumed that image at <addr1> should be used. If <addr1> is omitted, it is assumed that the current image address is to be used. For example, consider the following commands:

tftp 200000 /tftpboot/uImage
bootm :kernel-1
# Last command is equivalent to:
# bootm 200000:kernel-1

tftp 200000 /tftpboot/uImage
bootm 400000:kernel-1 :ramdisk-1
# Last command is equivalent to:
# bootm 400000:kernel-1 400000:ramdisk-1

tftp 200000 /tftpboot/uImage
bootm :kernel-1 400000:ramdisk-1 :fdt-1
# Last command is equivalent to:
# bootm 200000:kernel-1 400000:ramdisk-1 400000:fdt-1

Legacy boot

U-Boot supports a legacy image format, enabled by CONFIG_LEGACY_IMAGE_FORMAT. This is not recommended as it is quite limited and insecure. Use :doc:`../fit/index` instead. It is documented here for old boards which still use it.

Arguments are:

addr1
address of legacy image to boot. If the image includes a second component (ramdisk) it is used as well, unless the second parameter is hyphen '-'.
addr2
address of legacy image to use as ramdisk
addr3
address of legacy image to use as FDT

Example syntax

This section provides various examples of possible usage:

1.  bootm       /* boot image at the current address, equivalent to 2,3,8 */

This is equivalent to cases 2, 3 or 8, depending on the type of image at the current image address.

Boot method: see cases 2,3,8

Legacy uImage syntax

2.  bootm <addr1>            /* single image at <addr1> */

Boot kernel image located at <addr1>.

Boot method: non-FDT

3.  bootm <addr1>            /* multi-image at <addr1>  */

First and second components of the image at <addr1> are assumed to be a kernel and a ramdisk, respectively. The kernel is booted with initrd loaded with the ramdisk from the image.

Boot method: depends on the number of components at <addr1>, and on whether U-Boot is compiled with OF support, which it should be.

Configuration 2 components (kernel, initrd) 3 components (kernel, initrd, fdt)
#ifdef CONFIG_OF_* non-FDT FDT
#ifndef CONFIG_OF_* non-FDT non-FDT 
4.  bootm <addr1> -            /* multi-image at <addr1>  */

Similar to case 3, but the kernel is booted without initrd. Second component of the multi-image is irrelevant (it can be a dummy, 1-byte file).

Boot method: see case 3

5.  bootm <addr1> <addr2>        /* single image at <addr1> */

Boot kernel image located at <addr1> with initrd loaded with ramdisk from the image at <addr2>.

Boot method: non-FDT

6.  bootm <addr1> <addr2> <addr3>   /* single image at <addr1> */

<addr1> is the address of a kernel image, <addr2> is the address of a ramdisk image, and <addr3> is the address of a FDT binary blob. Kernel is booted with initrd loaded with ramdisk from the image at <addr2>.

Boot method: FDT

7.  bootm <addr1> -      <addr3>   /* single image at <addr1> */

<addr1> is the address of a kernel image and <addr3> is the address of a FDT binary blob. Kernel is booted without initrd.

Boot method: FDT

FIT syntax

8.  bootm <addr1>

Image at <addr1> is assumed to contain a default configuration, which is booted.

Boot method: FDT or non-FDT, depending on whether the default configuration defines FDT

9.  bootm [<addr1>]:<subimg1>

Similar to case 2: boot kernel stored in <subimg1> from the image at address <addr1>.

Boot method: non-FDT

10. bootm [<addr1>]#<conf>[#<extra-conf[#...]]

Boot configuration <conf> from the image at <addr1>.

Boot method: FDT or non-FDT, depending on whether the configuration given defines FDT

11. bootm [<addr1>]:<subimg1> [<addr2>]:<subimg2>

Equivalent to case 5: boot kernel stored in <subimg1> from the image at <addr1> with initrd loaded with ramdisk <subimg2> from the image at <addr2>.

Boot method: non-FDT

12. bootm [<addr1>]:<subimg1> [<addr2>]:<subimg2> [<addr3>]:<subimg3>

Equivalent to case 6: boot kernel stored in <subimg1> from the image at <addr1> with initrd loaded with ramdisk <subimg2> from the image at <addr2>, and pass FDT blob <subimg3> from the image at <addr3>.

Boot method: FDT

13. bootm [<addr1>]:<subimg1> [<addr2>]:<subimg2> <addr3>

Similar to case 12, the difference being that <addr3> is the address of FDT binary blob that is to be passed to the kernel.

Boot method: FDT

14. bootm [<addr1>]:<subimg1> -              [<addr3>]:<subimg3>

Equivalent to case 7: boot kernel stored in <subimg1> from the image at <addr1>, without initrd, and pass FDT blob <subimg3> from the image at <addr3>.

Boot method: FDT

  1. bootm [<addr1>]:<subimg1> - <addr3>

Similar to case 14, the difference being that <addr3> is the address of the FDT binary blob that is to be passed to the kernel.

Boot method: FDT

Example

boot kernel "kernel-1" stored in a new uImage located at 200000:

bootm 200000:kernel-1

boot configuration "cfg-1" from a new uImage located at 200000:

bootm 200000#cfg-1

boot configuration "cfg-1" with extra "cfg-2" from a new uImage located at 200000:

bootm 200000#cfg-1#cfg-2

boot "kernel-1" from a new uImage at 200000 with initrd "ramdisk-2" found in some other new uImage stored at address 800000:

bootm 200000:kernel-1 800000:ramdisk-2

boot "kernel-2" from a new uImage at 200000, with initrd "ramdisk-1" and FDT "fdt-1", both stored in some other new uImage located at 800000:

bootm 200000:kernel-1 800000:ramdisk-1 800000:fdt-1

boot kernel "kernel-2" with initrd "ramdisk-2", both stored in a new uImage at address 200000, with a raw FDT blob stored at address 600000:

bootm 200000:kernel-2 200000:ramdisk-2 600000

boot kernel "kernel-2" from new uImage at 200000 with FDT "fdt-1" from the same new uImage:

bootm 200000:kernel-2 - 200000:fdt-1

.. sectionauthor:: Bartlomiej Sieka <tur@semihalf.com>

.. sectionauthor:: Simon Glass <sjg@chromium.org>