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. A Walkthrough Of The New 32 System Open-Source Linux Benchmarking Test Farm
  2. Habey MITX-6771: Mini-ITX Board With Quad-Core J1900 Bay Trail
  3. OCZ Vector 150 SSD On Linux
  4. Noctua i4 CPU Cooler: Great For Cooling High-End LGA-2011v3 CPUs
Latest Linux Articles
  1. AMD Kaveri: Open-Source Radeon Gallium3D vs. Catalyst 14.12 Omega Driver
  2. 12-Way AMD Catalyst 14.12 vs. NVIDIA 346 Series Linux GPU Comparison
  3. AMD Catalyst 14.12 Omega Driver Brings Mixed Results For Linux Users
  4. 6-Way Winter 2014 Linux Distribution Comparison
Latest Linux News
  1. LLVM 3.6 Will Be Branched Next Month
  2. Opera Browser Puts Out Linux Updates For The Holidays
  3. GNOME Shell 3.15.3 Adds Support For High-Contrast Themes
  4. Linux 3.19: ThinkPad Muting Redone, New Dell Backlight Support, Acer Is Banging
  5. KVM Drops Support For IA64 While Adding Various x86 Improvements
  6. GCC 4.8.4 Officially Released
  7. FSF's High Priority Project List Now Has A Committee
  8. Details On Using OpenACC & GPUs With GCC
  9. Ubuntu 15.04 Alpha 1 For Its Various Flavors
  10. Git 2.2.1 Released To Fix Critical Security Issue
Latest Forum Discussions
  1. XLennart: A Game For Systemd Haters With Nothing Better To Do
  2. The New SuperTuxKart Looks Better, But Can Cause GPU/Driver Problems
  3. Debian init discussion in Phoenix Wright format
  4. FPS capped on Linux (AMD fglrx drivers)
  5. Are there an app using HSA ?
  6. Bench specific mount point
  7. Tool for measuring FPS in games
  8. Need some hand holding with upgrading xserver