Re: [PATCH] PCI: Expose ari_enabled in sysfs

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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,
>  };
>  



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