Compile-time Configuration

The hypervisor provides a kconfig-like way for manipulating compile-time configurations. Basically the hypervisor defines a set of configuration symbols and declare their default value. A configuration file is created, containing the values of each symbol, before building the sources.

Similar to Linux kconfig, there are three files involved:

  • .config This files stores the values of all configuration symbols.
  • config.mk This file is a conversion of .config in Makefile syntax, and can be included in makefiles so that the build process can rely on the configurations.
  • config.h This file is a conversion of .config in C syntax, and is automatically included in every source file so that the values of the configuration symbols are available in the sources.
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Figure 142 Hypervisor configuration and build workflow

Figure 142 shows the workflow of building the hypervisor:

  1. Three targets are introduced for manipulating the configurations.
    1. defconfig creates a .config based on a predefined configuration file.
    2. oldconfig updates an existing .config after creating one if it does not exist.
    3. menuconfig presents a terminal UI to navigate and modify the configurations in an interactive manner.
  2. The target oldconfig is also used to create a .config if a .config file does not exist when building the source directly.
  3. The other two files for makefiles and C sources are regenerated after .config changes.

Refer to Configuration Symbol Reference for a complete list of configuration symbols.