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

From: Simon Martin <furryfuttock@gmail.com>
To: Ian Campbell <Ian.Campbell@citrix.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>,
	Xenbegn developer <xen.begn.dev@gmail.com>,
	xen-devel@lists.xen.org,
	Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Subject: Re: [Query] Flow of PCI device dedicated to a domU
Date: Tue, 22 Jul 2014 17:06:28 +0100	[thread overview]
Message-ID: <1669742135.20140722170628@gmail.com> (raw)
In-Reply-To: <1406044966.32556.1.camel@kazak.uk.xensource.com>

Hello Ian,

>> 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?

> Stefano meant mapped in the p2m which under ARM or x86 HVM still means
> you need to make a virtual mapping of those PFNs.

> Under X86 PV "mapping" in this context really just means giving
> permission to map the underlying MFNs, so you still need to create a
> virtual mapping but they don't exist in your p2m until you put them
> there.

Thanks Ian, that is what I had understood from the mail that you sent
me on the thread I started about "Consuming PCI device in PV kernel".
Just wanted to confirm. I have just about worked my way up to
implementing the MMIO access now and wanted to make sure before I
carry on.

-- 
Best regards,
 Simon                            mailto:furryfuttock@gmail.com