Intel's powerful new Xeon Phi co-processor
Operating System
Because the Xeon Phi has full-fledged cores, not just highly optimized special-purpose computing units, it can run its own operating system. Intel leverages this ability to manage the board's resources and simplify software development.
When the host computer boots, the Xeon Phi first appears as a normal PCI device; the processor on the board is inactive. To activate the card, the host system's system management controller helps load an initrd image with a built-in BusyBox into the Xeon Phi's memory.
The Linux kernel used on the Xeon Phi differs only slightly from an ordinary x86 kernel; the necessary adjustments are comparable to those for an ARM image. After the image is transferred, the processor is started, and Linux is booted on the card for the first time. The coprocessor either uses initrd directly as the root filesystem, or it loads a filesystem from the host computer to the memory card, or it uses NFS to retrieve a filesystem.
Data Exchange
The PCIe bus allows the host system to write data to a memory expansion card. Conversely, expansion cards can also write to the memory of the host computer. However, writing directly to the memory of the host system is extremely awkward for an application programmer because this kind of low-level data transfer usually only takes place at the driver level. Intel therefore provides the Symmetric Communications Interface (SCIF), a library that includes an easy-to-use interface for low-level data transfer at the memory level. SCIF is the most efficient way of exchanging data between the host computer and the Xeon Phi card, and it also provides a means for transferring the root file system to the memory of the card.
Networking via Virtio
Intel has implemented additional data exchange options. The most important of these options integrates the card into a network. Intel uses the Virtio framework [5], among other things, for network access. Virtio provides virtual Ethernet interfaces on both the host system and the card's operating system, with the data traveling across the PCIe bus. The Ethernet interfaces operates in typical Linux style. In other words, the virtual Ethernet interface on the host operating system can connect to a physical port on the host computer and the Linux running on the card can join the local network via the virtual network interface (Figure 2).

Following the same principle, Intel has also implemented a virtual serial port and a virtual block device. The virtual serial port is designed to transfer the boot log, debug messages, and other status information to the host computer. The block device is actually intended to provide the Linux swap space on the card, but if you modify the init scripts supplied by Intel appropriately, it also provides a root filesystem and thus basically a fourth option for booting the card.
« Previous 1 2 3 Next »
Buy this article as PDF
(incl. VAT)
Buy Linux Magazine
Direct Download
Read full article as PDF:
Price $2.95
News
-
Titan Linux is a New KDE Linux Based on Debian Stable
Titan Linux is a new Debian-based Linux distribution that features the KDE Plasma desktop with a focus on usability and performance.
-
Danielle Foré Has an Update for elementary OS 7
Now that Ubuntu 22.04 has been released, the team behind elementary OS is preparing for the upcoming 7.0 release.
-
Linux New Media Launches Open Source JobHub
New job website focuses on connecting technical and non-technical professionals with organizations in open source.
-
Ubuntu Cinnamon 22.04 Now Available
Ubuntu Cinnamon 22.04 has been released with all the additions from upstream as well as other features and improvements.
-
Pop!_OS 22.04 Has Officially Been Released
From the makers of some of the finest Linux-powered desktop and laptop computers on the market comes the latest version of their Ubuntu-based distribution, Pop!_OS 22.04.
-
Star Labs Unveils a New Small Format Linux PC
The Byte Mk I is an AMD-powered mini Linux PC with Coreboot support and plenty of power.
-
MX Linux Verison 21.1 “Wildflower” Now Available
The latest release of the systemd-less MX Linux is now ready for public consumption.
-
Microsoft Expands Their Windows Subsystem for Linux Offerings With AlmaLinux
Anyone who works with Windows Subsystem for Linux (WSL) will now find a new addition to the available distributions, one that’s become the front-runner replacement for CentOS.
-
Debian 11.3 Released wIth Numerous Bug and Security Fixes
The latest point release for Debian Bullseye is now available with some very important updates.
-
The First Alpha of Asahi Linux is Available
Asahi Linux is the first distribution to fully support Apple Silicon and is now available for testing.