access usb device from bhyve vm

Rodney W. Grimes freebsd-rwg at
Sat Aug 25 02:56:55 UTC 2018

> I asked this on usb@, but might get a better bhyve perspective on this
> list...
> Does anyone have thought about what it would take to support access to
> individual usb devices "natively" from a bhyve vm?

The best though on this, and note I have not done this with bhyve,
but have done it with ESXi, is to get yourself a PCI USB card,
and pass the card in as a PCI device.

Note that for bhyve this requires a careful selection of
that PCI card, as the BAR's have to be page sized and
paged aligned to not have some issues getting it passed
in due to the fact that the IOMMU only works on pages
aligned and sized stuff.

I have asked about what magic would it take to make our
USB stack allow this and it is "non trivial".

Rod Grimes                                                 rgrimes at

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