1. Computers
  2. Display Drivers
  3. Graphics Cards
  4. Memory
  5. Motherboards
  6. Processors
  7. Software
  8. Storage
  9. Operating Systems


Facebook RSS Twitter Twitter Google Plus


Phoronix Test Suite

OpenBenchmarking.org

Intel Provides Linux PCI Express NTB Support

Intel

Published on 14 July 2012 07:42 AM EDT
Written by Michael Larabel in Intel
6 Comments

Intel has provided Linux kernel support for PCI Express Non-Transparent Bridges (NTB). PCI-E NTB allows for interconnecting multiple systems using PCI Express.

Jon Mason, one of the Intel engineers working on the Linux PCI Express Non-Transparent Bridge support, has a fairly lengthy commit message on his patch that describes this PCI-E bridge:
A PCI-Express non-transparent bridge (NTB) is a point-to-point PCIe bus connecting 2 systems, providing electrical isolation between the two subsystems. A non-transparent bridge is functionally similar to a transparent bridge except that both sides of the bridge have their own independent address domains. The host on one side of the bridge will not have the visibility of the complete memory or I/O space on the other side of the bridge. To communicate across the non-transparent bridge, each NTB endpoint has one (or more) apertures exposed to the local system. Writes to these apertures are mirrored to memory on the remote system. Communications can also occur through the use of doorbell registers that initiate interrupts to the alternate domain, and scratch-pad registers accessible from both sides.

The NTB device driver is needed to configure these memory windows, doorbell, and scratch-pad registers as well as use them in such a way as they can be turned into a viable communication channel to the remote system. ntb_hw.[ch] determines the usage model (NTB to NTB or NTB to Root Port) and abstracts away the underlying hardware to provide access and a common interface to the doorbell registers, scratch pads, and memory windows. These hardware interfaces are exported so that other, non-mainlined kernel drivers can access these. ntb_transport.[ch] also uses the exported interfaces in ntb_hw.[ch] to setup a communication channel(s) and provide a reliable way of transferring data from one side to the other, which it then exports so that "client" drivers can access them. These client drivers are used to provide a standard kernel interface (i.e., Ethernet device) to NTB, such that Linux can transfer data from one system to the other in a standard way.
This PCI Express technology isn't new, but is now finding its way to be supported by the mainline Linux kernel -- hopefully for the Linux 3.6 kernel.

A second patch by Jon Mason on Friday provides a virtual Ethernet device using the NTB transport API for sending and receiving data.

About The Author
Michael Larabel is the principal author of Phoronix.com and founded the web-site in 2004 with a focus on enriching the Linux hardware experience and being the largest web-site devoted to Linux hardware reviews, particularly for products relevant to Linux gamers and enthusiasts but also commonly reviewing servers/workstations and embedded Linux devices. Michael has written more than 10,000 articles covering the state of Linux hardware support, Linux performance, graphics hardware drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and OpenBenchmarking.org automated testing software. He can be followed via and or contacted via .
Latest Articles & Reviews
  1. Intel Broadwell HD Graphics 5500: Windows 8.1 vs. Linux
  2. Linux Benchmarks Of NVIDIA's Early 2015 GeForce Line-Up
  3. NVIDIA GeForce GTX 960: A Great $200 GPU For Linux Gamers
  4. Disk Encryption Tests On Fedora 21
  5. Xonotic 0.8 Performance With The Open-Source AMD/NVIDIA Gallium3D Drivers
  6. Many Linux Desktop 2D Benchmarks Of NVIDIA vs. AMD Drivers
Latest Linux News
  1. Linux Users Upset By Chromium's Busted HiDPI Support
  2. BPF Backend Merged Into LLVM To Make Use Of New Kernel Functionality
  3. Dying Light Is Headed To Linux, SteamOS
  4. Wayland 1.6.1 & Weston 1.6.1 Released
  5. Mesa 10.4.3 Brings A Bunch Of Fixes For The Direct3D "Nine" Support
  6. Intel Has A Few More Graphics Changes For The Linux 3.20 Kernel
  7. Gummiboot Gains PE File Searching Support To Find Linux Kernels
  8. Wine 1.7.35 Starts Working On OpenGL Core Context Support
  9. X.Org Server 1.17 Pre-Release "TimTam" Is Out
  10. Faster VP9 Decoding Is On The Horizon
Most Viewed News This Week
  1. Windows 10 To Be A Free Upgrade: What Linux Users Need To Know
  2. CoreOS Moves From Btrfs To EXT4 + OverlayFS
  3. Google Admin Encourages Trying Btrfs, Not ZFS On Linux
  4. TraceFS: The Newest Linux File-System
  5. Mozilla's Servo Still On Track For 2015 Alpha Release
  6. Fedora 23 Likely To Pursue Wayland By Default
  7. My Initial Intel Broadwell Linux Experience With The ThinkPad X1 Carbon
  8. Keith Packard Leaves Intel's Linux Graphics Work