Re: [Xen-devel] How to register a 64 bit BAR

[Pasi Kärkkäinen <pasik@xxxxxx>]

On Wed, Sep 24, 2014 at 12:47:01PM +0000, Zytaruk, Kelly wrote:
> Thanks Anthony, you have saved me hours of searching through the source code.
> 
> I am working with Xen 4.2 qemu-traditional.  I checked the source code for 
> upstream xen (qemu-xen-dir) and I didn't even find any support for the 
> pci_register_io_region() function.  Apparently BAR remapping callbacks aren't 
> supported in this version.  This is most unfortunate :-(
> 

Hmm.. I wonder if this old patch would be of any help?

http://lists.xen.org/archives/html/xen-devel/2012-08/msg01168.html


-- Pasi

> Thanks for the help,
> Kelly
> 
> > -----Original Message-----
> > From: Anthony PERARD [mailto:anthony.perard@xxxxxxxxxx]
> > Sent: Wednesday, September 24, 2014 5:53 AM
> > To: Zytaruk, Kelly
> > Cc: xen-devel@xxxxxxxxxxxxx
> > Subject: Re: [Xen-devel] How to register a 64 bit BAR
> > 
> > On Tue, Sep 23, 2014 at 08:33:08PM +0000, Zytaruk, Kelly wrote:
> > > I have used pci_register_io_region() to register 32 bit BARs but how do I
> > register a 64 bit BAR?
> > >
> > > Let's say my region uses BAR 2 and BAR 3 for a 64 bit address.  Do I
> > > register them separately as in
> > >
> > > pci_register_io_region (dev, 2, region_size, PCI_ADDRESS_SPACE_MEM,
> > > &my_func); pci_register_io_region (dev, 3, region_size, ???,
> > > &my_func);
> > 
> > No, that would register two different BARs.
> > 
> > > What would I specify as a region type for BAR 3?
> > 
> > Nothing, since you don't want two different BARs.
> > 
> > > Or is QEMU smart enough for me to register just BAR 2 and it will know
> > somehow that it is a 64 bit BAR?
> > 
> > Nop.
> > 
> > > I also want to call cpu_register_physical_memory() from within the 
> > > callback
> > but the callback only takes a uint32_t as a physical address.
> > > I am having difficulty finding an example that uses a 64 bit BAR address.
> > 
> > Look for where PCI_ADDRESS_SPACE_MEM is define, and you will find how to
> > register a 64bit BAR.
> > Unless your are speaking about qemu-traditional and I'm not sure that is
> > possible.
> > 
> > After looking in the source code of qemu-traditional, it does not appear to
> > support 64bit BAR. Only QEMU upstream handle them (also called qemu-xen).
> > 
> > --
> > Anthony PERARD
> 
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