Performing partial builds

By using the LIST tag in the makefile, you can cause the make command to perform a partial build, even if you're at the top of the source tree.

If you were to simply type make without having used the LIST tag, all directories would be recursed into and everything would be built.

However, by defining a macro on make's command line, you can:

• recurse into only the specified tagged directories

  Or:

• recurse into all of the directories except for the specified tagged ones

Let's consider an example. The following (issued from the top of the source tree):

make CPULIST=x86

causes only the directories that are at the CPU level and below (and tagged as LIST=CPU), and that are called x86, to be recursed into.

You can specify a space-separated list of directories (note the use of quoting in the shell to capture the space character):

make "CPULIST=x86 arm"

This causes the x86 and ARM versions to be built.

There's also the inverse form, which causes the specific lists not to be built:

make EXCLUDE_CPULIST=arm

This causes everything except the ARM versions to be built.

As you can see from the above examples, the following are all related to each other via the CPU portion:

• LIST=CPU
• CPULIST
• EXCLUDE_CPULIST