Title The story of the Linux kernel Linus Torvalds explains what makes the Linux kernel great Summary In this excerpt from O'Reilly & Associates' newly-released book "Open Sources: Voices from the Open Source Revolution," Linus Torvalds explains some of the key architectural decisions he made in bringing the Linux kernel to its present state. (5,000 words) [omitted...] Keeping the kernel healthy With a monolithic kernel such as the Linux kernel, it's important to be very cautious about allowing new code and new features into the kernel. These decisions can affect a number of things later on in the development cycle beyond the core kernel work. The first very basic rule is to avoid interfaces. If someone wants to add something that involves a new system interface you need to be exceptionally careful. Once you give an interface to users they will start coding to it and once somebody starts coding to it you are stuck with it. Do you want to support the exact same interface for the rest of your system's life? Other code is not so problematic. If it doesn't have an interface, say a disk driver, there isn't much to think about; you can just add a new disk driver with little risk. If Linux didn't have that driver before, adding it doesn't hurt anyone already using Linux, and opens Linux to some new users. [omitted...] The complete article is available online at http://www.linuxworld.com/linuxworld/lw-1999-03/lw-03-opensources.html --Hans