Attach a GPS in preboot mode

[Peter Krempa]

On Tue, Jan 24, 2023 at 00:10:46 +0100, lnj.sam at gmail.com wrote:
> Hello everyone and best wishes for 2023 :)
> 
> I have an old *Garmin Drive Smart 50 GPS* and I want to be able to attach it
> when it is in preboot mode to a VM hosted by a *Debian 11 host*.
> 
> From what I understand, the preboot mode allows us to flash a firmware
> before the GPS actually starts (used among other things when the GPS is soft
> bricked).
> 
> When I connect the GPS to the host it gives:

[...]

> My questions :
> 
> Q1 : Is it possible ?

It shpi;d be/

> 
> Q2 : Am I doing it the right way ?

I don't think so. You are using a serial device emulated which is then
connected to the host side USB-tty device.

A better way is simply to use USB-assignment/passthrough and have the
guest OS handle also the USB side

> 
> Q3 : Is there a method to pass such a device directly (pass-through) ?

To pass a USB device use the following XML: 

    <hostdev mode='subsystem' type='usb' managed='yes'>
      <source>
        <vendor id='0x1a86'/>
        <product id='0x55d4'/>
      </source>
      <address type='usb' bus='0' port='4'/>
    </hostdev>

Obviously tweak vendor/product.

Alternatively when you are using virt-manager GUI there's a menu to pass
any device, or by default when you have a VM window active and plug in a
USB device it's passed to the VM. (It can be disabled though).