Re: [Qemu-devel] [PATCH 0/5][RFC] virtio-net: MAC filtering

[Avi Kivity]

Paul Brook wrote:
> > A concern here is the growing size of the virtio-net I/O port space
> > config.  This series brings it up to 256 bytes with PCI resource
> > rounding.  The VLAN filter bitmap would increase that by another 512
> > bytes, making it 1kB and limiting us to something less than 64 such
> > devices per guest.  Is anyone worried?  Should filter tables live in
> > MMIO space for virtio devices?  I'll send out the guest side patches for
> > virtio-net in a separate thread.  Thanks,
> >     
>
> This is one reason why IO ports are a reallybad idea. Use memory mapped 
> register spaces like any other sane system and you won't have a problem.
>   

mmio is slower for virtualization.  But I agree pio is baroque.

Luckily we didn't implement the 768 pci slot thing, that wouldn't have 
flown (for yet another reason).

--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.