Question about ixgbe and ixgbevf

Question about ixgbe and ixgbevf

[Kevin Wilson]

Hi,
I have an x86_64 machine (F21) on which ixgbevf is not loaded.
I notices that when running
modprobe ixgbevf max_vfs = 10 (or any other number), this triggers
loading of ixgbevf driver.
I will appreciate if someone can exaplain the implementation details
of how does this happen.
I could not find what in the ixgbe driver code triggers this action

Regards,
Kevni

Question about ixgbe and ixgbevf

[Biju Abraham]

Hey Kevin,
   This is basically because of udevd calling modprobe when the new
VFs are created. The code in the ixgbe driver that causes the VFs to
be created would be the function call "pci_enable_sriov()". This
brings about a chain of events resulting in the ixgbevf getting
loaded.
I assume you want to assign the VFs to VMs rather than have ixgbevf
load and take control of the VFs. So, you will have to black list the
ixgbevf driver in your host operating system.
For more information on the udev, udevd and modprobe check out
(section 7.4.2.4) :
http://www.linuxfromscratch.org/lfs/view/6.4/chapter07/udev.html

- Biju


On Mon, Mar 23, 2015 at 11:15 AM, Kevin Wilson <wkevils@gmail.com> wrote:
> Hi,
> I have an x86_64 machine (F21) on which ixgbevf is not loaded.
> I notices that when running
> modprobe ixgbevf max_vfs = 10 (or any other number), this triggers
> loading of ixgbevf driver.
> I will appreciate if someone can exaplain the implementation details
> of how does this happen.
> I could not find what in the ixgbe driver code triggers this action
>
> Regards,
> Kevni
>
> _______________________________________________
> Kernelnewbies mailing list
> Kernelnewbies at kernelnewbies.org
> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies

Question about ixgbe and ixgbevf

[Bjørn Mork]

Kevin Wilson <wkevils@gmail.com> writes:

> Hi,
> I have an x86_64 machine (F21) on which ixgbevf is not loaded.
> I notices that when running
> modprobe ixgbevf max_vfs = 10 (or any other number), this triggers
> loading of ixgbevf driver.
> I will appreciate if someone can exaplain the implementation details
> of how does this happen.
> I could not find what in the ixgbe driver code triggers this action


max_vfs is a deprecated method for setting an initial value for
adapter->num_vfs.  You'll normally use sysfs to add VFs today.


If you look at this extremely over-long ixgbe_probe() function in
ixgbe_main.c then you'll find this:

	pci_sriov_set_totalvfs(pdev, IXGBE_MAX_VFS_DRV_LIMIT);
	ixgbe_enable_sriov(adapter);


... and then looking at ixgbe_enable_sriov() in ixgbe_sriov.c :

		err = pci_enable_sriov(adapter->pdev, adapter->num_vfs);


If you're interested in the gory details here, then I suggest looking at
Documentation/PCI/pci-iov-howto.txt . But it is sufficient to know that
this creates a number of new PCI devices with IDs which is then matched
by the ixgbevf driver.  That driver will then be autoloaded and probed
for all the new VF PCI devices, just like any other hotplugged PCI
device works.



Bj?rn