integrated processors.
3.2.12. Other ARM
More than 100 semiconductor companies are developing integrated solutions based on ARM technologyfar too many to list here. Many offer specialized application processors serving vertical markets such as the handset market, storage area networking, network processing, and the automotive market, as well as many more. These companies include Altera, PMC-Sierra, Samsung Electronics, Philips Semiconductor, Fujitsu, and more. See the ARM Technologies website at www.arm.com for additional ARM licensees and information.
3.2.13. Other Architectures
We have covered the major architectures in widespread use in embedded Linux systems. However, for completeness, you should be aware of other architectures for which support exists in Linux. A recent Linux snapshot revealed 25 architecture branches (subdirectories). In some instances, the 64-bit implementation of an architecture is separated from its 32-bit counterpart. In other cases, ports are not current or are no longer maintained.
The Linux source tree contains ports for Sun Sparc and Sparc64, the Xtensa from Tensilica, and the v850 from NEC, to name a few. Spend a few minutes looking through the architecture branches of the Linux kernel to see the range of architectures for which Linux has been ported. Beware, however, that not all these architectures might be up-to-date in any given snapshot. You can be reasonably certain that the major architectures are fairly current, but the only way to be certain is to follow the development in the Linux community or consult with your favorite embedded Linux vendor. Appendix E, 'Open Source Resources,' contains a list of resources you can consult to help you stay current with Linux developments.
3.3. Hardware Platforms
The idea of a common hardware reference platform is not new. The venerable PC/104 and VMEbus are two examples of hardware platforms that have withstood the test of time in the embedded market.[24] More recent successful platforms include CompactPCI and its derivatives.
3.3.1. CompactPCI
The CompactPCI (cPCI) hardware platform is based on PCI electrical standards and Eurocard physical specifications. cPCI has the following general features:
• Vertical cards of 3U or 6U heights
• Latch system for securing and ejecting cards
• Front- or rear-panel I/O connections supported
• High-density backplane connector
• Staggered power pins for hot-swap support
• Support by many vendors
• Compatibility with standard PCI chipsets
You can view highlights of and obtain specifications for the cPCI architecture at the PCI Industrial Computer Manufacturers Group (PICMG) cPCI web page, at www.picmg.org/compactpci.stm.
3.3.2. ATCA
A successor to the successful cPCI, Advanced Telecommunications Computing Architecture is the name given to the architecture and platforms designed around the PICMG 3.
ATCA platforms are leading the industry trend away from in-house proprietary hardware and software platforms. Many of the largest equipment manufacturers in the telecommunications and networking markets have been slowly moving away from the custom, in-house-designed hardware platforms. This trend is also evident in the software platforms, from operating systems to so-called middleware such as high-availability and protocol stack solutions. Downsizing and time-to-market pressures are two key factors driving this trend.
ATCA is defined by several PICMG specifications. Table 3-11 summarizes these specifications.
Table 3-11. ATCA PICMG 3.x Specification Summary
| Specification | Summary |
|---|---|
| PICMG 3.0 | Mechanical specifications, including interconnects, power, cooling, and base system management |
| PICMG 3.1 | Ethernet and Fiber Channel switching fabric interface |
| PICMG 3.2 | Infiniband switching fabric interface |
| PICMG 3.3 | StarFabric interface |
| PICMG 3.4 | PCI Express interface |
