Re: [edk2-devel] [PATCH v2 1/2] OvmfPkg/Bhyve: add USB support

["Peter Grehan" <grehan@freebsd.org>]

>>> Is that a detail of the current implementation, or a fundamental 
>>> limitation in the bhyve architecture?
>>
>>   Only two choices ? :) Maybe half way between those points.
> 
> When there is no fundamental limitation,

  It's not so much a fundamental technical limitation as in a large 
amount of work in FreeBSD for almost zero return - maybe a fundamental 
resource limitation.

> i.e. when a future version of 
> the hypervisor may be able to support the feature with no changes to the 
> firmware, then it would be good practice to leave the drivers enabled. 
> Doing so avoids creating an unnecessarily tight coupling between the 
> hypervisor and firmware versions.
  Well versed in those issues :)

> More importantly: does it even matter that the hypervisor doesn't 
> support passthrough of PCI legacy interrupts?  UEFI operates on a 
> polling basis, with the only active interrupt being some kind of 
> periodic timer.  Where do you see any requirement for legacy interrupts 
> in the UHCI/EHCI drivers?

  It creates a case where the o/s booted by EFI isn't able to use those 
controllers as expected.

  Anyways, this is more a discussion for the freebsd-virtualization 
mailing list if you'd like to chat about it more.

later,

Peter.