Intel X540-T2BP IXGBE bypass feature support

What?

This repository holds a set of patches for the IXGBE Linux Kernel driver for providing it support for the bypass feature available on some Intel NICs. These patches have been mainly derived from the DPDK IXGBE driver and the FreeBSD IXGBE driver implementations (they don't necessarily support this feature for X540-based NICs, but the way it works is exactly the same than in others).

The bypass feature is a feature that allows some 10 Gbit Intel network cards with two RJ45 ports to put themselves in a state where the ports are physically attached together, effectively allowing the traffic to flow from one port to another without going through the NIC, even when it is powered off. This feature may be useful for building networks that goes through the card without a need of an extra switch (I don't know, maybe ring networks or something?) and making sure they don't fail if the server where they are attached to does.

This repository includes patches to make sure the X540-T2BP network card is catched by the IXGBE driver and exposes the bypass feature through sysfs, to be managed from the userspace. Even though the bypass feature is supported on more NICs, this repository only focuses on the X540 because it is the one I have at home and I can use for testing.

This driver is not intended for production use, since it lacks important things like concurrency controls.

Building

Fully download this repository with: git clone --recursive <repo path>. The command will download the repository alongside the Linux kernel and Busybox (for testing).

Then, run make apply-patches to apply the patches over the current Kernel commit.

Finally, run make build-dev-kernel to build the kernel. The build config is optimized for fast building and to be ran on a QEMU virtual machine. Config is located at dev/kernel-dev-config and can be customized.

Testing

Testing is done in a QEMU virtual machine, an this repository holds a couple of scripts to make testing easier and faster.

Firstly, make sure you have installed all the QEMU required packages. In ArchLinux, these are the following:

• qemu-base
• qemu-common
• qemu-hw-usb-host
• qemu-img
• qemu-system-x86
• qemu-system-x86-firmware

Secondly, navigate to the dev/run-virt.sh and make the necessary changes to perform a PCI passthrough of the network card you want to test with from your host machine to the virtual machine. Some guidance here.

Finally, run make build-and-run, which will run anther the hood the targets build-dev-kernel, build-dev-initramfs for generating a boot image with Busybox, and then run-dev-machine which will just run the QEMU emulator.

Developing

Once you've ran the make apply-patches command, you may start coding on top of the latest commit under the linux/ folder. Once you're done, commit the changes and run make build-patches. That will create one patch file per new commit in the patches/ folder.