Re: [Xen-devel] [Query] Flow of PCI device dedicated to a domU

[Simon Martin <furryfuttock@xxxxxxxxx>]

Hello Stefano,

> The basic mechanism is that Xen assigns the PCI root complex/host
> bridge to Dom0. Dom0 walks the bus and finds out the devices available.

> When the user assigns a PCI device to a VM, the toolstack (xl/libxl)
> issues hypercalls to remap interrupts and MMIO regions of that device
> into the guest VM.

I am currently trying writing my own PCI front to access directly a
PCI device from my PV guest.

If I read this correctly you are saying that the MMIO region is
already mapped into my domain by xl? So when I go and read the BAR
register from the PCI configuration I can just go and access it
directly or do I have to update the VA mapping?

-- 
Best regards,
 Simon                            mailto:furryfuttock@xxxxxxxxx


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