![]() Such magic occurs on other operating systems too, like UNIX and NT. Maintaining (via the library) a considerable amount of data However, the magic of the library doesn't come without cost, and that cost is: This is all done through the magic of the library. Each thread created, from the first one that runs through main to the last, also has specific data items, the best example of which is errno. ![]() From then on, data like the current screen, the current NDS tree, open files, and so on, are all kept in account by the library. The start- up code called from that object sets up the application's private data and then ultimately calls main. The instancing begins by the application NLM's use of the library's prelude code, linked into the NLM using prelude.obj. While NKS/LibC (see the series of five articles begun in the September 1999 issue of Developer Notes and running until the following December) also has issues of context-they are virtually identical to CLib's-we will only speak of CLib context here to represent the issue.Įach NLM uses static data that, from the library's point of view, must be instanced for each of its consuming NLMs. KLib's relationship to the two main library environments on NetWare.Īlso called thread context, thread-library context, or CLib context, it is the glue that makes of an NLM and its threads an application. (Lib0 through NIT and CLib are the NLMs that make up the CLib library.)įigure 1. In interest of anyone who cares, the accompanying diagram illustrates KLib's relationship to the two main library environments on NetWare. Load-dependence is an observed phenomenon on NetWare. ![]() KLib loads at the bottom of the heap, speaking of libraries, and offers its services to CLib, NKS, LibC, and to any other component running on NetWare, be it driver, protocol stack, library, or application. ![]() KLib satisfies these two conditions because the interfaces it furnishes don't require library context nor do they rely on static data to preserve state from one call to another. Nowdays, these developers also want intrinsically thread-safe interfaces, interfaces that operate on stack-based data (called auto-class in C) to perform operations that other threads, calling the same interfaces, cannot corrupt. (We'll touch on what library context is in a moment.) While they have been able to consume these interfaces from CLib without needing context, the way to do it was somewhat shrouded in uncertainty. However, since it mostly provides symbols that were formerly provided by CLib, existing applications need not concern themselves with existence (or non existence).ĭevelopers of drivers, protocol stacks, other kernel code, and also libraries want standard C runtime interfaces like strcpy and yet don't usually want to write their code in terms of library context. To find out which ones and when, please contact Novell Developer Support. Is being delivered in service packs on NetWare as far back as NetWare 4.11. Is the basis for many libraries on NetWare in that it furnishes a great number of common interfaces KLib provides them at this lower level for consumption by low-level code as well as applications. They are well-suited to drivers, stacks, libraries, and other low-level code. Consequently, KLib interfaces are completely reentrant and thread-safe. KLib interfaces act only upon input parameters and, when making use of global or other data not passed in through the interface (an example is _ctype), treat such data as read-only. In any case, the furnished functionality has no obligation to library concepts of thread binding, context, and ownership. The K in KLib stands for kernel because these functions might have been provided and consumed at that level. KLib is implemented by KLib.NLM and supplies interfaces which were once the domain of CLib to NLM developers that don't want to load atop CLib. This article covers a new runtime library, KLib, in use on the NetWare operating system. Debugging and Functions Called from KLib, CLib, and LibC.How to Write Drivers and Other Components to KLib instead of CLib.In this AppNote, we will elaborate on this new library and discuss development-related issues and techniques that leave the domain of application programming (based on CLib or NKS/LibC) and enter the domain of code that is properly thought of as kernel-level.
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