CODEWITHSUNDEEP
linux-kernellinux-device-driverpci-evfio
Patrick Collins
Patrick Collins

Reputation: 10574

How do PCIe devices advertise multiple virtual functions to Linux?

SR-IOV lets PCIe devices expose a single physical function and multiple virtual functions. How does the kernel detect that a device supports virtual functions? Is it a part of the PCIe configuration registers? Where in the kernel are devices tested for how many functions they export?

EDIT: I'm looking for a line of code (or a file) in the kernel source that inspects a PCIe device in order to determine how many virtual functions it exports. I'd also settle for a link to the appropriate standard that lays out what information a device needs to send to the host in order to report that it supports multiple virtual functions.

Upvotes: 3

Views: 1209

Answers (1)

prl
prl

Reputation: 12435

An SR-IOV capable device defines the SR-IOV Capability (extended capability ID 10h).

This is specified in chapter 9 of the PCI Express Base specification revision 4.0. I'm not sure whether you can find a free copy online; you may need to be a PCI-SIG member.

In the Linux kernel, look for PCI_EXT_CAP_ID_SRIOV and PCI_SRIOV_TOTAL_VF in drivers/pci/iov.c.

Upvotes: 2

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