Using WSL and 'dd' to Image U-Boot Firmware to SDcard

Last time there was something I forgot to cover, because everything was going so smoothly that I completely forgot that I was even using WSL, and thus should try to cover anything unusual about using WSL in this situation.

So this will quickly cover how you can get a USB device in Windows (like a sdcard reader) to show up in WSL as a block device.

Note that this is specific to USB devices, and non-USB devices will need a different method of pass-through.

1. Install Software

For things to execute in PowerShell in windows I’ll use the prompt PS> and for WSL I’ll use > as the bash prompt.

The two software packages I’m recommending for this are:

1. USBipd-win
2. gsudo (optional) - proper sudo for Windows

The second is technically optional, because you can also just run PowerShell as an administrator for the one command that needs it.

Easiest way to get these:

winget install dorssel.usbipd-win
winget install gerardog.gsudo
$env:PATH += ";$env:ProgramFiles\usbipd-win"
Import-Module gsudoModule

2. Eject SDCard

If you have anything inserted in your card reader that windows has mounted, you want to “eject” it (unmount it). usbipd will need to make the device unavailable to Windows to make it available to WSL. So Windows won’t be happy if it disappears when a mounted storage volume is depending on it.

3. Identify USB Device VID/PID

Windows unfortunately makes this a pain, but extra work may not be needed due to a nice option in usbipd list.

PS>  usbipd list -u
Connected:
BUSID  VID:PID    DEVICE                                                        STATE
...
9-4    1189:8840  Acer Communications & Multimedia, Unknown device              Not shared
14-1   05e3:0751  Genesys Logic, Inc., microSD Card Reader                      Not shared
14-4   25a4:9311  Unknown device                                                Not shared

You can also try it without the -u but usually -u will be more useful since Windows only has generic names for these things, like “usb mass storage device”.

Another way, in case it’s needed, is to try to dig this out of Windows. One way to do it is to run this, which isn’t ideal but I’m not willing to write a whole PowerShell script to do a better job (which is what would be required):

PS> Get-PnpDevice -PresentOnly -Class "DiskDrive" | foreach-object { $_ | Get-PnpDeviceProperty DEVPKEY_name ; $_ | Get-PnpDeviceProperty DEVPKEY_Device_Parent } | format-table KeyName, Data
...
KeyName               Data
-------               ----
DEVPKEY_name          ADATA EC700G SCSI Disk Device
DEVPKEY_Device_Parent USB\VID_0BDA&PID_A03A\MSFT30000000001160
DEVPKEY_name          Generic STORAGE DEVICE USB Device
DEVPKEY_Device_Parent USB\VID_05E3&PID_0751\6&2b3456b5&0&1

In this case I know the ADATA one is a large USB SSD, and the “Generic Storage Device” is the card reader. These are usually going to show up as generic USB storage devices just like USB thumb drives.

What we can use here is the USB\VID_05E3&PID_0751 part which tells us we want to use the one with VID=0x05E3 and PID=0x0751.

Comparing with the above, we can see that this matches the one with busid 14-1.

So now we know what we need to attach to WSL.

4. Bind Device to USBIPD

PS> usbipd bind -h
usbipd-win 5.1.0

Description:
  Registers a single USB device for sharing, so it can be attached to other machines. Unless the --force option is used, shared devices remain available to the host
  until they are attached to another machine.

  Exactly one of the options '--busid' or '--hardware-id' is required.

Usage:
  usbipd bind [options]

Options:
  -b, --busid <BUSID>          Share device having <BUSID>
  -f, --force                  Force binding; the host cannot use the device
  -i, --hardware-id <VID:PID>  Share device having <VID>:<PID>
  -?, -h, --help               Show help and usage information

This will install a driver that will allow the device to be “attached” when needed, but left for windows to use the rest of the time.

PS> gsudo usbipd bind --busid <insert actual ID here> # or --hardware-id <VID:PID>

Once that’s done, you no longer need Administrator privileges to attach or detach the device from now on. So as a normal user:

PS> usbipd attach --wsl --busid <busid> # or use --hardware-id <VID:PID>
usbipd: info: Using WSL distribution 'Ubuntu' to attach; the device will be available in all WSL 2 distributions.
usbipd: info: Detected networking mode 'nat'.
usbipd: info: Using IP address 172.21.192.1 to reach the host.

When you want to give this back to windows, just run the usbipd detach command in the same manner.

5. Insert the SDCard

What the heading says.

6. Use Device in WSL

The easiest way to confirm that the device showed up in wWSL is this:

> dmesg
.... lots of stuff ...
[91285.792564] scsi 1:0:0:0: Direct-Access     Generic  STORAGE DEVICE   1404 PQ: 0 ANSI: 6
[91285.794836] sd 1:0:0:0: Attached scsi generic sg6 type 0
[91286.034145] sd 1:0:0:0: [sdg] 31459328 512-byte logical blocks: (16.1 GB/15.0 GiB)
[91286.037572] sd 1:0:0:0: [sdg] Write Protect is off
[91286.037576] sd 1:0:0:0: [sdg] Mode Sense: 21 00 00 00
[91286.040275] sd 1:0:0:0: [sdg] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA
[91286.091552]  sdg: sdg1 sdg2
[91286.092386] sd 1:0:0:0: [sdg] Attached SCSI removable disk

You should see something like that. lsusb can also be used but it’s more trouble to get the block device out of it.

In my case, the device is /dev/sdg

And now you can use dd or whatever meeds direct low level access to the device in WSL and flash the U-Boot firmware/bootloader like this.

Epilog

Apparently there’s also some documentation about connecting USB devices to WSL at Microsoft Dev Blogs. (However, it looks like the first part about installing linux-tools in WSL Ubuntu is no longer necessary, and I think the whole article might be way out of date at this point.)