ABI conformance

You should seriously consider the benefits of building your products in conformance with the binary compatibility specification that matches your intended market. For UnixWare and other UNIX System V derived operating systems on the Intel architecture, this specification can be found in the following documents:

• System V Application Binary Interface (ABI)

  Discusses ABI issues that are generic to all hardware platforms.

• System V ABI Intel Processor Supplement

  Covers issues that are specific to the Intel platform.

• ABI+ Specification for Intel Architectures

  An extension of the ABI with additional Intel specifics.

These specifications include information for both system vendors and application developers. For system developers, they specify the APIs that must be provided, and the formats of binary files and data that are necessary for binary compatibility. For application developers, they list the APIs guaranteed to be present on conforming systems, and the way applications should be built and packaged so that their binaries will install and run on all conforming systems.

The benefit of using an ABI is that the same binary distribution of your product runs on systems from many vendors, rather than having to be ported and compiled separately for each system. You can sell each shrink-wrapped unit into a significantly larger market than would otherwise be the case.

The ABIs also specify:

• the object file format (the content and layout of the information that compiler objects present to system loaders and linkers, for example, exec, ld, and rtld)

• how an application communicates with the system

• system call numbers, error numbers, ioctls

• size and layout of basic and aggregate system data types

• the environment an application can expect at startup

• contents and layouts of system administrative files

• how different modules of an application communicate

• function call conventions (how arguments are passed, how values are returned)

• size and layout of basic data types

• size and layout of aggregate data types -- structures, unions, bit-fields