From mboxrd@z Thu Jan  1 00:00:00 1970
From: Simon Martin <furryfuttock@gmail.com>
Subject: Re: [Query] Flow of PCI device dedicated to a domU
Date: Tue, 22 Jul 2014 16:56:57 +0100
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To: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>, Xenbegn developer <xen.begn.dev@gmail.com>, ian.campbell@citrix.com, xen-devel@lists.xen.org
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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@gmail.com