Re: [Xen-devel] pv_ops reassigndev for pci passthrough

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Mon, Dec 28, 2009 at 10:22:02AM -0500, Michael D Labriola wrote:
> > As a hack you can eliminate the check in the Xend python code for this
> > and see how far you can go. Just remember that it is a hack :-)
> 
> Might try this if I get a spare moment... just to see what happens ;-)
> 
> > I had not ported it over. My thought was to write code in the pciback 
> code
> > that would do this automatically (if BARs are found to be not BAR 
> aligned).
> > 
> > Thought I am unsure of why this was not explored - are there any 
> badtechnical
> > reasons to make BARs page-aligned after the device has been enabled (and 
> then
> > disabled)?
> > 
> > I am taking aside the Linux kernel resources structs (request_resource
> > and its friends), which probabally will throw a fit.
> 
> Yeah, I always kinda wondered why this wasn't done automatically by 
> pciback.  Having pciback do it would mean that even non-BAR aligned 
> devices could be exported after booting and w/out specifying PCI IDs as 
> kernel args.  That would be one fewer issue to fix later in the 
> upstreaming effort.

So this is actually implemented in the pvops kernel, but has a different
name: pci=resource_alignment=<BDF>

This is what you need to pass as bootup argument, for example:

xen-pciback.hide=(07:00.0)(08:05.0)(08:07.0)(08:07.2) 
pci=resource_alignment=08:05.0 

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