RE: [Xen-devel] [PATCH][VTD] enable integrated graphics passthrough for Calpella and Sandybridge

["Kay, Allen M" <allen.m.kay@xxxxxxxxx>]

> Can you register a dummy device at the address corresponding to IGD and
> get the pci conf read and write calls directly from the functions you
> pass to pci_register_device?

I'm not sure what do you mean...

The issue is IGD driver accesses some registers in device 0:0.0.  However, we 
don't want to passthrough platform's 0:0.0 to the guest as it will change the 
guest's chipset wholesale thus create more problems than it solves.  For now, 
we are keeping the 440 chipset's 0:0.0 device but passthrough certain register 
accesses.

Isaku proposed register another set of read/write function for guest's device 
0:0.0 instead of modifying existing functions.  The advantage of this approach 
is that original QEMU read/write function will be left unmodified for IGD 
purpose.  The disadvantage is this requires making a copy of exiting code and 
redirect all read/write handling of 0:0.0 device to a function in 
pt-graphics.c.  I tried it out but found the resulting code a bit confusing.

Allen

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