host command


host bind [-r] <label> [<filename>]
host unbind <label|seq>
host info [<label|seq>]
host dev [<label|seq>]


The host command provides a way to attach disk images on the host to U-Boot sandbox. This can be useful for testing U-Boot’s filesystem implementations.

Common arguments:


This is used to specify a host device. It can either be a label (a string) or the sequence number of the device. An invalid value causes the command to fail.

host bind

This creates a new host device and binds a file to it.



Label to use to identify this binding. This can be any string.


Host filename to bind to



Mark the device as removable

host unbind

This unbinds a host device that was previously bound. The sequence numbers of other devices remain unchanged.

host info

Provides information about a particular host binding, or all of them.

host dev

Allowing selecting a particular device, or (with no arguments) seeing which one is selected.


Initially there are no devices:

=> host info
dev       blocks label           path

Bind a device:

=> host bind -r test2 2MB.ext2.img
=> host bind fat 1MB.fat32.img
=> host info
dev       blocks label           path
  0         4096 test2           2MB.ext2.img
  1         2048 fat             1MB.fat32.img

Select a device by label or sequence number:

=> host dev fat
Current host device: 1: fat
=> host dev 0
Current host device: 0: test2

Write a file:

=> ext4write host 0 0 /dump 1e00
File System is consistent
7680 bytes written in 3 ms (2.4 MiB/s)
=> ext4ls host 0
<DIR>       4096 .
<DIR>       4096 ..
<DIR>      16384 lost+found
            4096 testing
            7680 dump

Unbind a device:

=> host unbind test2
=> host info
dev       blocks label           path
  1         2048 fat             1MB.fat32.img

Return value

The return value $? indicates whether the command succeeded.