As the subject is coming round to peripherals, and I'm just compeleting an
NDIS NIC
driver (windows MAC driver), I thought I'd add my 2c worth.
Having 2 (or more) OSs accessing a network card at the same time, totally
ignorant
of each other, is somewhat undesirable (virtually guarantees that networking
won't
work for either OS). So, what to do... For windows as the guest, one
approach would
be to create a standard NDIS driver and punt the actual operation to the
host. This
would be easiest if the Windows networking was TCP/IP based. This is the
usual case
anyway. All IP traffic could be punted to the host OS, leaving only a few
oddballs
(like DHCP and ARP) that may have to be directly emulated. NIC addresses
could be
a problem for DHCP and ARP, but I'm sure we can work around it somehow - by
setting
the adapter into promicuous mode, if nothing else.
This would involve spoofing the PCI bus, so that the windows guest thought
it had
a suitable NIC to play with, figuring some mechanism to pass requests to the
host
to the guest, writing a guest handler to redirect the network traffic,
implementing
a "virtual interrupt" mechanism whereby the host could cause the guest OS to
"see"
a hardware interrupt and of course, writing a NIC driver for windows that
will
work with Plex86 (and provide a suitable NIC address - one that won't
conflict with
the rest of the LAN).
I just had another thought. There's no reason why the sends and receives
could not
work at the ethernet, except that the host would have to recognize both its
own NIC
address and the Guest NIC address - could be done in promiscuous mode, with
the host
driver filtering (this could be costly in machine cycles)... In this case,
we would
have to make sure that the host driver would recognize its own NIC address,
and
loop-back any packets that the Guest sent to it.
Either way, we would want a virtual card for windows, and a driver to handle
it, a
virtual interrupt mechanism, PCI spoofing, a communication mechanism to the
host
from the guest and vice-versa. Thinking about it, PCI spoofing is probably
going to
play a big role in peripheral handling, whatever it is. This is probably a
VIP
(Very Important sub-Project).
