The following is Inder Singh's answer to the question, “What is Linux?” . . .

Much like the legend of the five blind men and the elephant, Linux means different things to different people, depending on their perspective and needs,.

I believe Linux is primarily two things: (1) an excellent open source operating system technology, and (2) an open standard platform for software that runs on Linux, as defined by the Linux APIs and ABIs. Both of these aspects are very significant for the current and future success of Linux.

The former has a lot to do with the where Linux is today, but it is the latter aspect of Linux as a platform for a growing base of open source as well as commercial applications in particular, that Linux will have its greatest impact on the computer industry.

The open source community development model, with the Web playing a crucial role, has been key to both the quality and robustness of Linux as well as its popularity, and this will continue to be a major strength. In the embedded market, the royalty fee nature makes it very attractive for very high volume cost-sensitive applications such as many of the emerging “post PC” appliance type of products. The wide availability of source and a huge and growing web based developer community facilitates quick availability of support for new semiconductor devices including ports to new CPU architectures. This makes Linux an important vehicle for tracking the technology curve.

The key to Linux maintaining its momentum, and having the huge impact on the computer industry that many proponents are hoping for, lies in its achieving wide acceptance as an open standard platform for applications.

The fact that Linus chose to implement the UNIX interfaces rather than simply create a new operating system and that Linux substantially conforms to POSIX has been largely responsible for its popularity, and it further strengthens its position as an open standard.

In the embedded world, this aspect of Linux is particularly significant, because this is such a fragmented industry without any kind of a standard or leading platform. Around half of all embedded designs still use in-house operating systems, and the leading commercial RTOS product accounts for only a fraction of new embedded designs. As a result, the embedded world is missing a robust software industry such as the software industry that developed around DOS and Windows for the desktop. Embedded developers do a lot of reinventing the wheel and developing much more software from scratch instead of building on top of existing tools and application software like their mainstream counterparts.

Linux as an open standard has the potential to serve as the missing platform that can foster an embedded software industry. As embedded applications are becoming more complex, the boundary between embedded and mainstream applications is blurring. So more and more of the software becoming available on Linux is already useful for embedded developers.

Thus, one answer to the question “Is it Linux?” which may be the most meaningful is that it is Linux if it can run Linux applications, i.e. defining Linux in terms of its APIs/ABIs. This is the aspect that is most important to developers of Linux applications as well as to most embedded Linux developers. It is key to preventing Linux from fragmenting the way that Unix did.

The Linux Standard Base (LSB) project, whose specific goal is “to develop and promote a set of standards that will increase compatibility among distributions and enable software applications to run on any compliant Linux system” is intended to prevent this very problem. It deserves strong support from application developers and users.

From this perspective, products like LynxOS from LynuxWorks, which has a high degree of compliance with the Linux APIs, and will support the ABIs in a future release, are effectively more true to Linux than some of the open source solutions like RTLinux and Zentropix which are derived from Linux, but break the Linux APIs to provide real-time performance.

 
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