NetWare Loadable Module

A NetWare Loadable Module (NLM) is a loadable kernel module (a binary code module) that can be loaded into Novell's NetWare operating system. NLMs can implement hardware drivers, server functions (e.g. clustering), applications (e.g. GroupWise), system libraries or utilities.

NLMs were supported beginning with the Intel 80386-based NetWare version 3.x. Prior versions of NetWare had a monolithic kernel, and significant hardware or functionality changes required re-linking the kernel from object modules.

Due to stability issues with early third-party NLMs, they never became popular for server application programming, with few exceptions like antivirus programs, backup programs and certain database products.

Functionality

Upon loading, a NLM requests resources, such as memory and process threads, from the NetWare kernel. The NetWare kernel tracks such requests, and can identify memory and other resources assigned to a specific NLM. NLMs may auto-load other NLMs upon which they themselves depend.