Re: [PATCH 1/4] PCI: Add #defines for accessing PCIe DVSEC fields

[Greg KH]

On Sat, Nov 20, 2021 at 03:17:02PM -0800, David E. Box wrote:
> Add #defines for accessing Vendor ID, Revision, Length, and ID offsets
> in the Designated Vendor Specific Extended Capability (DVSEC). Defined
> in PCIe r5.0, sec 7.9.6.
> 
> Signed-off-by: David E. Box <david.e.box@xxxxxxxxxxxxxxx>
> Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> ---
>  include/uapi/linux/pci_regs.h | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
> index ff6ccbc6efe9..318f3f1f9e92 100644
> --- a/include/uapi/linux/pci_regs.h
> +++ b/include/uapi/linux/pci_regs.h
> @@ -1086,7 +1086,11 @@
>  
>  /* Designated Vendor-Specific (DVSEC, PCI_EXT_CAP_ID_DVSEC) */
>  #define PCI_DVSEC_HEADER1		0x4 /* Designated Vendor-Specific Header1 */
> +#define  PCI_DVSEC_HEADER1_VID(x)	((x) & 0xffff)
> +#define  PCI_DVSEC_HEADER1_REV(x)	(((x) >> 16) & 0xf)
> +#define  PCI_DVSEC_HEADER1_LEN(x)	(((x) >> 20) & 0xfff)
>  #define PCI_DVSEC_HEADER2		0x8 /* Designated Vendor-Specific Header2 */
> +#define  PCI_DVSEC_HEADER2_ID(x)		((x) & 0xffff)

Why does userspace need to have these defines?  What userspace tool is
going to use these?

thanks,

greg k-h