Cell Linux port heads for mainstream kernel tree
Jun 27, 2005 — by Henry Kingman — from the LinuxDevices Archive — views[Updated Jun. 29, 2005] — IBM, Sony, and Toshiba have ported Linux to the Cell processor, and hope to merge their patches into the next major Linux kernel release, 2.6.13. The port includes a 64-bit PowerPC kernel, and a filesystem availing it of the chip's multiple independent vector processing units.
IBM's developerWorks has published a detailed, technical article about the port.
The Cell processor is expected to power Sony's Playstation 3, rumored to be slated for worldwide rollout in March of 2006. However, the chip's co-creators said in December of last year, when they first revealed architectural details, that workstations — not Playstations — represented the chip's initial target market. Now, according to developerworks, it appears the Cell will see use initially in blade computers for powerful multi-board systems.
The Cell processor was scheduled to begin pilot production at IBM's 300mm wafer fabrication facility in East Fishkill, New York in the first half of this year. The chip was designed at IBM's Austin, Texas research facility, after IBM, Sony, and Toshiba jointly committed more than $400M to the project in March of 2001.
Like so many new chips being introduced these days, the Cell processor has a multi-core design. It is not an SMP (symmetric multiprocessing) multi-core chip, but instead has a primary 64-bit PowerPC core clocked up to 4GHz, and augmented by multiple independent vector processors called Synergistic Processing Units (SPUs).
According to the developerWorks article, Linux ports readily to the Cell, since Linux has long supported 64-bit PowerPC chips such as those used in Apple Power Macintoshes and IBM's pSeries line of 4- to 16-way enterprise servers. However, taking advantage of the SPUs required additional work.
The Cell team has “done the groundwork” for a Linux kernel port, the developerWorks article says, including porting Linux to the Cell's primary PowerPC core. True to the Linux way of looking at everything as a file, the team also created a virtual filesystem called Spufs (Synergistic processing unit filesystem) that abstracts SPU resources, enabling the Linux kernel to load program binaries into an SPU, transfer memory between an SPU program and a Linux userspace application, and synchronize execution.
The article concludes, “With the current state of Linux on Cell, you can write special-purpose applications running on the prototype board while using the full performance of the chip. While most applications do not immediately run better on Cell, there is a lot of potential to port performance-critical applications to use library code running on an SPU for better performance.”
The article additionally reveals, “The current set of kernel patches is based on the latest 2.6.xx snapshot kernel, and is maintained by the IBM LTC (Linux Technology Center) team in Böblingen, Germany. The team hopes to integrate most of this into the 2.6.13 kernel release, so it will become part of upcoming distribution releases.”
Read the full developerWorks story for complete details:
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