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 Linux Hardware Reviews
  1. Rosewill RS-MI-01: An Ultra Low-Cost Mini-ITX Chassis
  2. D-Link DCS-2330L HD Wireless Network Camera
  3. Gigabyte AM1M-S2H
  4. AMD's New Athlon/Semprons Give Old Phenom CPUs A Big Run For The Money
Latest Linux Articles
  1. Red Hat Enterprise Linux 7.0 RC Benchmarks
  2. AMD Catalyst 14.4 Brings Few Linux Performance Improvements
  3. The Performance Of Fedora 20 Updated
  4. Clang Fights GCC On AMD's Athlon AM1 APU With Jaguar Cores
Latest Linux News
  1. More Steam Linux Tests/Benchmarks Might Be Coming
  2. NVIDIA's Amazing Single-Board ARM Computer Might Be Delayed
  3. Fedora 21 To Get A Playground, New Features
  4. PC-BSD Is Developing Its Own Desktop Environment
  5. Valve Is Bringing VOGL To Windows & Working On Regression Tests
  6. Canonical Is Taking Over Linux 3.13 Kernel Maintenance
  7. Google Web Designer Is Now Natively Available On Linux
  8. Ubuntu 14.10 Is Codenamed The Utopic Unicorn
  9. Audacious 3.5 Lightweight Audio Player Released
  10. Steam Updated For Ubuntu 14.04 LTS, SteamOS
  11. DNF 0.5 Yum Replacement Now Supports Groups
  12. Red Hat Enterprise Linux 7.0 Is Looking Fantastic
Latest Forum Discussions
  1. HTPC-upgrade advice: AMD Richland A8-7600 or Kaveri A10-6700T ???
  2. The GNOME Foundation Is Running Short On Money
  3. What Else Would You Like To See On Phoronix This Spring?
  4. Linux Kernel Developers Fed Up With Ridiculous Bugs In Systemd
  5. The Most Amazing OpenGL Tech Demo In 64kb
  6. Announcing radeontop, a tool for viewing the GPU usage
  7. New card. Open source drivers only.
  8. Script for Fan Speed Control