On Fri, Jan 05, 2018 at 12:51:55PM -0600, Stuart Hayes wrote:
> Some multifunction PCI devices with more than 8 functions use "alternative
> routing-ID interpretation" (ARI), which means the 8-bit device/function
> number field will be interpreted as 8 bits specifying the function number
> (the device number is 0 implicitly), rather than the upper 5 bits
> specifying the device number and the lower 3 bits specifying the function
> number. The kernel can enable and use this.
>
> Expose in a sysfs attribute whether the kernel has enabled ARI, so that a
> program in userspace won't have to parse PCI devices and PCI configuration
> space to figure out if it is enabled. This will allow better predictable
> network naming using PCI function numbers without using PCI bus or device
> numbers, which is desirable because bus and device numbers can change with
> system configuration but function numbers will not.
>
> Signed-off-by: Stuart Hayes <stuart.w.hayes@xxxxxxxxx>
Applied to pci/virtualization for v4.16, thanks!
> ---
>
> --- linux-4.15-rc6/drivers/pci/pci-sysfs.c.orig 2017-12-31 17:47:43.000000000 -0500
> +++ linux-4.15-rc6/drivers/pci/pci-sysfs.c 2018-01-02 13:58:23.372928377 -0500
> @@ -278,6 +278,16 @@ static ssize_t subordinate_bus_number_sh
> }
> static DEVICE_ATTR_RO(subordinate_bus_number);
>
> +static ssize_t ari_enabled_show(struct device *dev,
> + struct device_attribute *attr,
> + char *buf)
> +{
> + struct pci_dev *pci_dev = to_pci_dev(dev);
> +
> + return sprintf(buf, "%u\n", pci_ari_enabled(pci_dev->bus));
> +}
> +static DEVICE_ATTR_RO(ari_enabled);
> +
> static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
> char *buf)
> {
> @@ -786,6 +796,7 @@ static struct attribute *pci_dev_attrs[]
> &dev_attr_devspec.attr,
> #endif
> &dev_attr_driver_override.attr,
> + &dev_attr_ari_enabled.attr,
> NULL,
> };
>
