Merging

The role of mkmerge is to link the source files and the component's build directory. For further information, see the mkmerge(1CC) man page.

The code for ChorusOS components which contain family specific code is organized in split trees. Within the split trees, there are subtrees for:

• common code, that is, the code shared by all the platforms

• code that is related to specific families (for example, PowerPC, ppc60x) or CPU

Before generation begins, subtrees are merged into a merged tree. There is only one merged tree in each merged component. Initially, it contains symbolic, or hard, links that point to files in the split trees. The build takes place in the merged tree, so the split trees remain free of generated files, such as object files and Makefiles. You can delete a merged tree at any time. This will not affect the source code, as it remains clean in the split tree.

From a given set of subtrees of the split tree, different merged trees can be built. This allows you to produce several system configurations concurrently.

Building the merged tree is called the merge operation. When performing this operation, you provide a number of first-level options, called generation options. These options correspond to fundamental production choices, such as the choice of a development system or the target family and are typically found in the build profile given in Table 4-1.

If you are using the mkmk tool on a system running the Solaris operating environment, mkmerge populates the merge directory with symbolic links. These links point to the source directories required for your build.

If you are using the mkmk tool on a Windows NT system, mkmerge creates hard links between the source directories and your <work_dir>. The use of hard links permits you to use Windows NT hosts to edit files in the <work_dir>.