Crostini USB Support flag not available on Pixelbook for dev Chrome OS

[Mitchell Harper]

Apologies if this is a dupe or there is documentation I'm missing,

I just purchased a stock Pixelbook now running 78.0.3877.0 after updates.

I am running in the "dev" channel.

However, for the flag "chrome://flags/#crostini-usb-support", the message is that it is "Not available on your platform."

Is there a workaround for enabling the flag, or if not is there a different set of documentation for more experimental ways of passing USB devices through to the Crostini container?

[Ben Wells]

We'll fix the confusing message. This flag is now enabled by default, so you don't need to do anything to turn on USB support. Note that the currently supported devices are just Android devices. If you want more device support, you can try the #crostini-usb-allow-unsupported flag, which allows more devices to be passed into the container (e.g. some serial devices like Arduino).

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[Mitchell Harper]

Thank you very much!

One last question, is there currently a whitelist of what device classes are enabled for serial passthrough? I am currently at CCCamp playing with the Fomu FPGA toolchain (https://github.com/im-tomu/fomu-workshop) and the DFU flash works, however the serial console that is supposed to appear afterward is not available for passthrough after flashing.

This is the current lsusb on the host after flashing (device 47 is the device we care about):

Bus 002 Device 022: ID 0bda:8153 Realtek Semiconductor Corp. 
Bus 002 Device 021: ID 05e3:0749 Genesys Logic, Inc. 
Bus 002 Device 020: ID 2109:0817  
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 046: ID 2109:8888  
Bus 001 Device 047: ID 1209:5bf0 InterBiometrics 
Bus 001 Device 044: ID 2109:2817  
Bus 001 Device 027: ID 8087:0a2a Intel Corp. 
Bus 001 Device 026: ID 0bda:564b Realtek Semiconductor Corp. 
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
/:  Bus 02.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/6p, 5000M
    |__ Port 2: Dev 20, If 0, Class=Hub, Driver=hub/4p, 5000M
        |__ Port 1: Dev 21, If 0, Class=Mass Storage, Driver=usb-storage, 5000M
        |__ Port 4: Dev 22, If 0, Class=Vendor Specific Class, Driver=r8152, 5000M
/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/12p, 480M
    |__ Port 2: Dev 26, If 0, Class=Video, Driver=uvcvideo, 480M
    |__ Port 2: Dev 26, If 1, Class=Video, Driver=uvcvideo, 480M
    |__ Port 3: Dev 27, If 0, Class=Wireless, Driver=btusb, 12M
    |__ Port 3: Dev 27, If 1, Class=Wireless, Driver=btusb, 12M
    |__ Port 5: Dev 44, If 0, Class=Hub, Driver=hub/5p, 480M
        |__ Port 3: Dev 47, If 0, Class=Communications, Driver=cdc_acm, 12M
        |__ Port 3: Dev 47, If 1, Class=CDC Data, Driver=cdc_acm, 12M
        |__ Port 5: Dev 46, If 0, Class=, Driver=, 480M

It appears the driver is "cdc_acm" which may be a non-standard driver.

Also please let me know if a bug is the more appropriate place to file/discuss this issue.

[Mitchell Harper]

Dug in a little further, this seems to be an issue in the permission broker, filed https://bugs.chromium.org/p/chromium/issues/detail?id=996197