bootflow command

Synopis

bootflow scan [-abelGH] [bootdev]
bootflow list [-e]
bootflow select [<num|name>]
bootflow info [-d]
bootflow boot

Description

The bootflow command is used to manage bootflows. It can scan bootdevs to locate bootflows, list them and boot them.

See U-Boot Standard Boot for more information.

bootflow scan

Scans for available bootflows, optionally booting the first valid one it finds. This operates in two modes:

  • If no bootdev is selected (see bootdev select) it scans bootflows one by one, extracting all the bootdevs from each

  • If a bootdev is selected, it just scans that one bootflow

Flags are:

-a

Collect all bootflows, even those that cannot be loaded. Normally if a file is not where it is expected, then the bootflow fails and so is dropped during the scan. With this option you can see why each bootflow would be dropped.

-b

Boot each valid bootflow as it is scanned. Typically only the first bootflow matters, since by then the system boots in the OS and U-Boot is no-longer running. bootflow scan -b is a quick way to boot the first available OS. A valid bootflow is one that made it all the way to the loaded state.

-e

Used with -l to also show errors for each bootflow. The shows detailed error information for each bootflow that failed to make it to the loaded state.

-l

List bootflows while scanning. This is helpful when you want to see what is happening during scanning. Use it with the -b flag to see which bootdev and bootflows are being tried.

-G

Skip global bootmeths when scanning. By default these are tried first, but this flag disables them.

-H

Don’t use bootdev hunters. By default these are used before each boot priority or label is tried, to see if more bootdevs can be discovered, but this flag disables that process.

The optional argument specifies a particular bootdev to scan. This can either be the name of a bootdev or its sequence number (both shown with bootdev list). Alternatively a convenience label can be used, like mmc0, which is the type of device and an optional sequence number. Specifically, the label is the uclass of the bootdev’s parent followed by the sequence number of that parent. Sequence numbers are typically set by aliases, so if you have ‘mmc0’ in your devicetree alias section, then mmc0 refers to the bootdev attached to that device.

bootflow list

Lists the previously scanned bootflows. You must use bootflow scan before this to see anything.

If you scanned with -a and have bootflows with errors, -e can be used to show those errors.

The list looks something like this:

Seq

Method

State

Uclass

Part

Name

Filename

0

distro

ready

mmc

2

mmc@7e202000.bootdev.part_2

/boot/extlinux/extlinux.conf

1

pxe

ready

ethernet

0

smsc95xx_eth.bootdev.0

rpi.pxe/extlinux/extlinux.conf

The fields are as follows:

Seq:

Sequence number in the scan, used to reference the bootflow later

Method:

The boot method (bootmeth) used to find the bootflow. Several methods are included in U-Boot.

State:

Current state of the bootflow, indicating how far the bootdev got in obtaining a valid one. See Bootflow states for a list of states.

Uclass:

Name of the media device’s Uclass. This indicates the type of the parent device (e.g. MMC, Ethernet).

Part:

Partition number being accesseed, numbered from 1. Normally a device will have a partition table with a small number of partitions. For devices without partition tables (e.g. network) this field is 0.

Name:

Name of the bootflow. This is generated from the bootdev appended with the partition information

Filename:

Name of the bootflow file. This indicates where the file is on the filesystem or network device.

bootflow select

Use this to select a particular bootflow. You can select it by the sequence number or name, as shown in bootflow list.

Once a bootflow is selected, you can use bootflow info and bootflow boot.

If no bootflow name or number is provided, then any existing bootflow is unselected.

bootflow info

This shows information on the current bootflow, with the format looking like this:

Name

mmc@7e202000.bootdev.part_2

Device

mmc@7e202000.bootdev

Block dev

mmc@7e202000.blk

Type

distro

Method:

syslinux

State

ready

Partition

2

Subdir

(none)

Filename

/extlinux/extlinux.conf

Buffer

3db7ad48

Size

232 (562 bytes)

FDT:

<NULL>

Error

0

Most of the information is the same as bootflow list above. The new fields are:

Device

Name of the bootdev

Block dev

Name of the block device, if any. Network devices don’t have a block device.

Subdir

Subdirectory used for retrieving files. For network bootdevs this is the directory of the ‘bootfile’ parameter passed from DHCP. All file retrievals when booting are relative to this.

Buffer

Buffer containing the bootflow file. You can use the md command to look at it, or dump it with bootflow info -d.

Size

Size of the bootflow file

FDT:

Filename of the device tree, if supported. The EFI bootmeth uses this to remember the filename to load. If <NULL> then there is none.

Error

Error number returned from scanning for the bootflow. This is 0 if the bootflow is in the ‘loaded’ state, or a negative error value on error. You can look up Linux error codes to find the meaning of the number.

Use the -d flag to dump out the contents of the bootfile file.

bootflow boot

This boots the current bootflow.

Example

Here is an example of scanning for bootflows, then listing them:

U-Boot> bootflow scan -l
Scanning for bootflows in all bootdevs
Seq  Type         State   Uclass    Part  Name                      Filename
---  -----------  ------  --------  ----  ------------------------  ----------------
Scanning bootdev 'mmc@7e202000.bootdev':
  0  distro       ready   mmc          2  mmc@7e202000.bootdev.p    /extlinux/extlinux.conf
Scanning bootdev 'sdhci@7e300000.bootdev':
Card did not respond to voltage select! : -110
Scanning bootdev 'smsc95xx_eth.bootdev':
Waiting for Ethernet connection... done.
BOOTP broadcast 1
DHCP client bound to address 192.168.4.30 (4 ms)
Using smsc95xx_eth device
TFTP from server 192.168.4.1; our IP address is 192.168.4.30
Filename 'rpi.pxe/'.
Load address: 0x200000
Loading: *
TFTP error: 'Is a directory' (0)
Starting again

missing environment variable: pxeuuid
Retrieving file: rpi.pxe/pxelinux.cfg/01-b8-27-eb-a6-61-e1
Waiting for Ethernet connection... done.
Using smsc95xx_eth device
TFTP from server 192.168.4.1; our IP address is 192.168.4.30
Filename 'rpi.pxe/pxelinux.cfg/01-b8-27-eb-a6-61-e1'.
Load address: 0x2500000
Loading: ##################################################  566 Bytes
     45.9 KiB/s
done
Bytes transferred = 566 (236 hex)
  1  distro       ready   ethernet     0  smsc95xx_eth.bootdev.0 rpi.pxe/extlinux/extlinux.conf
No more bootdevs
---  -----------  ------  --------  ----  ------------------------  ----------------
(2 bootflows, 2 valid)
U-Boot> bootflow l
Showing all bootflows
Seq  Type         State   Uclass    Part  Name                      Filename
---  -----------  ------  --------  ----  ------------------------  ----------------
  0  distro       ready   mmc          2  mmc@7e202000.bootdev.p    /extlinux/extlinux.conf
  1  pxe          ready   ethernet     0  smsc95xx_eth.bootdev.0     rpi.pxe/extlinux/extlinux.conf
---  -----------  ------  --------  ----  ------------------------  ----------------
(2 bootflows, 2 valid)

The second one is then selected by name (we could instead use bootflow sel 0), displayed and booted:

U-Boot> bootflow info
No bootflow selected
U-Boot> bootflow sel mmc@7e202000.bootdev.part_2
U-Boot> bootflow info
Name:      mmc@7e202000.bootdev.part_2
Device:    mmc@7e202000.bootdev
Block dev: mmc@7e202000.blk
Sequence:  1
Method:    distro
State:     ready
Partition: 2
Subdir:    (none)
Filename:  extlinux/extlinux.conf
Buffer:    3db7ae88
Size:      232 (562 bytes)
Error:     0
U-Boot> bootflow boot
** Booting bootflow 'smsc95xx_eth.bootdev.0'
Ignoring unknown command: ui
Ignoring malformed menu command:  autoboot
Ignoring malformed menu command:  hidden
Ignoring unknown command: totaltimeout
1:  Fedora-Workstation-armhfp-31-1.9 (5.3.7-301.fc31.armv7hl)
Retrieving file: rpi.pxe/initramfs-5.3.7-301.fc31.armv7hl.img
get 2700000 rpi.pxe/initramfs-5.3.7-301.fc31.armv7hl.img
Waiting for Ethernet connection... done.
Using smsc95xx_eth device
TFTP from server 192.168.4.1; our IP address is 192.168.4.30
Filename 'rpi.pxe/initramfs-5.3.7-301.fc31.armv7hl.img'.
Load address: 0x2700000
Loading: ###################################T ###############  57.7 MiB
     1.9 MiB/s
done
Bytes transferred = 60498594 (39b22a2 hex)
Retrieving file: rpi.pxe//vmlinuz-5.3.7-301.fc31.armv7hl
get 80000 rpi.pxe//vmlinuz-5.3.7-301.fc31.armv7hl
Waiting for Ethernet connection... done.
Using smsc95xx_eth device
TFTP from server 192.168.4.1; our IP address is 192.168.4.30
Filename 'rpi.pxe//vmlinuz-5.3.7-301.fc31.armv7hl'.
Load address: 0x80000
Loading: ##################################################  7.2 MiB
     2.3 MiB/s
done
Bytes transferred = 7508480 (729200 hex)
append: ro root=UUID=9732b35b-4cd5-458b-9b91-80f7047e0b8a rhgb quiet LANG=en_US.UTF-8 cma=192MB cma=256MB
Retrieving file: rpi.pxe//dtb-5.3.7-301.fc31.armv7hl/bcm2837-rpi-3-b.dtb
get 2600000 rpi.pxe//dtb-5.3.7-301.fc31.armv7hl/bcm2837-rpi-3-b.dtb
Waiting for Ethernet connection... done.
Using smsc95xx_eth device
TFTP from server 192.168.4.1; our IP address is 192.168.4.30
Filename 'rpi.pxe//dtb-5.3.7-301.fc31.armv7hl/bcm2837-rpi-3-b.dtb'.
Load address: 0x2600000
Loading: ##################################################  13.8 KiB
     764.6 KiB/s
done
Bytes transferred = 14102 (3716 hex)
Kernel image @ 0x080000 [ 0x000000 - 0x729200 ]
## Flattened Device Tree blob at 02600000
   Booting using the fdt blob at 0x2600000
   Using Device Tree in place at 02600000, end 02606715

Starting kernel ...

[  OK  ] Started Show Plymouth Boot Screen.
[  OK  ] Started Forward Password R…s to Plymouth Directory Watch.
[  OK  ] Reached target Local Encrypted Volumes.
[  OK  ] Reached target Paths.
....

Here we scan for bootflows and boot the first one found:

U-Boot> bootflow scan -bl
Scanning for bootflows in all bootdevs
Seq  Method       State   Uclass    Part  Name                    Filename
---  -----------  ------  --------  ----  ----------------------  ----------------
Scanning bootdev 'mmc@7e202000.bootdev':
  0  distro       ready   mmc          2  mmc@7e202000.bootdev.p  /extlinux/extlinux.conf
** Booting bootflow 'mmc@7e202000.bootdev.part_2'
Ignoring unknown command: ui
Ignoring malformed menu command:  autoboot
Ignoring malformed menu command:  hidden
Ignoring unknown command: totaltimeout
1:  Fedora-KDE-armhfp-31-1.9 (5.3.7-301.fc31.armv7hl)
Retrieving file: /initramfs-5.3.7-301.fc31.armv7hl.img
getfile 2700000 /initramfs-5.3.7-301.fc31.armv7hl.img
Retrieving file: /vmlinuz-5.3.7-301.fc31.armv7hl
getfile 80000 /vmlinuz-5.3.7-301.fc31.armv7hl
append: ro root=UUID=b8781f09-e2dd-4cb8-979b-7df5eeaaabea rhgb LANG=en_US.UTF-8 cma=192MB console=tty0 console=ttyS1,115200
Retrieving file: /dtb-5.3.7-301.fc31.armv7hl/bcm2837-rpi-3-b.dtb
getfile 2600000 /dtb-5.3.7-301.fc31.armv7hl/bcm2837-rpi-3-b.dtb
Kernel image @ 0x080000 [ 0x000000 - 0x729200 ]
## Flattened Device Tree blob at 02600000
   Booting using the fdt blob at 0x2600000
   Using Device Tree in place at 02600000, end 02606715

Starting kernel ...

[    0.000000] Booting Linux on physical CPU 0x0

Here is am example using the -e flag to see all errors:

U-Boot> bootflow scan -a
Card did not respond to voltage select! : -110
Waiting for Ethernet connection... done.
BOOTP broadcast 1
DHCP client bound to address 192.168.4.30 (4 ms)
Using smsc95xx_eth device
TFTP from server 192.168.4.1; our IP address is 192.168.4.30
Filename 'rpi.pxe/'.
Load address: 0x200000
Loading: *
TFTP error: 'Is a directory' (0)
Starting again

missing environment variable: pxeuuid
Retrieving file: rpi.pxe/pxelinux.cfg/01-b8-27-eb-a6-61-e1
Waiting for Ethernet connection... done.
Using smsc95xx_eth device
TFTP from server 192.168.4.1; our IP address is 192.168.4.30
Filename 'rpi.pxe/pxelinux.cfg/01-b8-27-eb-a6-61-e1'.
Load address: 0x2500000
Loading: ##################################################  566 Bytes
     49.8 KiB/s
done
Bytes transferred = 566 (236 hex)
U-Boot> bootflow l -e
Showing all bootflows
Seq  Type         State   Uclass    Part  Name                   Filename
---  -----------  ------  --------  ----  ---------------------  ----------------
  0  distro       fs      mmc          1  mmc@7e202000.bootdev.p /extlinux/extlinux.conf
     ** File not found, err=-2
  1  distro       ready   mmc          2  mmc@7e202000.bootdev.p /extlinux/extlinux.conf
  2  distro       fs      mmc          3  mmc@7e202000.bootdev.p /extlinux/extlinux.conf
     ** File not found, err=-1
  3  distro       media   mmc          0  mmc@7e202000.bootdev.p <NULL>
     ** No partition found, err=-2
  4  distro       media   mmc          0  mmc@7e202000.bootdev.p <NULL>
     ** No partition found, err=-2
  5  distro       media   mmc          0  mmc@7e202000.bootdev.p <NULL>
     ** No partition found, err=-2
  6  distro       media   mmc          0  mmc@7e202000.bootdev.p <NULL>
     ** No partition found, err=-2
  7  distro       media   mmc          0  mmc@7e202000.bootdev.p <NULL>
     ** No partition found, err=-2
  8  distro       media   mmc          0  mmc@7e202000.bootdev.p <NULL>
     ** No partition found, err=-2
  9  distro       media   mmc          0  mmc@7e202000.bootdev.p <NULL>
     ** No partition found, err=-2
  a  distro       media   mmc          0  mmc@7e202000.bootdev.p <NULL>
     ** No partition found, err=-2
  b  distro       media   mmc          0  mmc@7e202000.bootdev.p <NULL>
     ** No partition found, err=-2
  c  distro       media   mmc          0  mmc@7e202000.bootdev.p <NULL>
     ** No partition found, err=-2
  d  distro       media   mmc          0  mmc@7e202000.bootdev.p <NULL>
     ** No partition found, err=-2
  e  distro       media   mmc          0  mmc@7e202000.bootdev.p <NULL>
     ** No partition found, err=-2
  f  distro       media   mmc          0  mmc@7e202000.bootdev.p <NULL>
     ** No partition found, err=-2
 10  distro       media   mmc          0  mmc@7e202000.bootdev.p <NULL>
     ** No partition found, err=-2
 11  distro       media   mmc          0  mmc@7e202000.bootdev.p <NULL>
     ** No partition found, err=-2
 12  distro       media   mmc          0  mmc@7e202000.bootdev.p <NULL>
     ** No partition found, err=-2
 13  distro       media   mmc          0  mmc@7e202000.bootdev.p <NULL>
     ** No partition found, err=-2
 14  distro       ready   ethernet     0  smsc95xx_eth.bootdev.0 rpi.pxe/extlinux/extlinux.conf
---  -----------  ------  --------  ----  ---------------------  ----------------
(21 bootflows, 2 valid)
U-Boot>

Return value

On success bootflow boot normally boots into the Operating System and does not return to U-Boot. If something about the U-Boot processing fails, then the return value $? is 1. If the boot succeeds but for some reason the Operating System returns, then $? is 0, indicating success.

For other subcommands, the return value $? is always 0 (true).