Commit 0077a845 authored Jan 05, 2018 by Stuart Hayes Committed by Bjorn Helgaas Jan 23, 2018

PCI: Expose ari_enabled in sysfs



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@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

parent aa008206

drivers/pci/pci-sysfs.c

+11 −0

Original line number	Diff line number	Diff line
		@@ -278,6 +278,16 @@ static ssize_t subordinate_bus_number_show(struct device *dev,
		}
		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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