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RE: [PATCH] pci-hyperv: Use only 16 bit integer for PCI domain




> -----Original Message-----
> From: Bjorn Helgaas [mailto:bhelgaas@xxxxxxxxxx]
> Sent: Thursday, April 20, 2017 2:33 PM
> To: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
> Cc: linux-pci@xxxxxxxxxxxxxxx; KY Srinivasan <kys@xxxxxxxxxxxxx>;
> Stephen Hemminger <sthemmin@xxxxxxxxxxxxx>; olaf@xxxxxxxxx;
> vkuznets@xxxxxxxxxx; driverdev-devel@xxxxxxxxxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH] pci-hyperv: Use only 16 bit integer for PCI domain
> 
> On Thu, Apr 20, 2017 at 11:35 AM, Haiyang Zhang
> <haiyangz@xxxxxxxxxxxxxxxxxxxxxx> wrote:
> > From: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
> >
> > This patch uses the lower 16 bits of the serial number as PCI
> > domain, otherwise some drivers may not be able to handle it.
> 
> Can you give any more details about this?  Which drivers, for
> instance?  Why do drivers care about the domain at all?  Can we or
> should we make this more explicit and consistent in the PCI core,
> e.g., pci_domain_nr() is currently defined to return "int"; maybe it
> should be u32?  (Although I think "int" is the same size as "u32" on
> all arches anyway).

It's Nvidia driver.

Piotr, could you explain why the driver expects 16 bit domain number?

Thanks,
- Haiyang