While working with the Linux kernel, I encountered a situation where some kernel configuration options did not appear explicitly in the .config file. To investigate further, I manually tested a few flags by adding code that intentionally fails the build if those flags are enabled, but I found no evidence of any such flag being active without appearing in the .config.
Here are my questions:
- Is it possible for a Kconfig option to be implicitly enabled through dependencies or defaults but not explicitly listed in .config?
- How do select directives, auto-selection, or architecture-specific conditions affect the visibility of flags in .config?
- Could certain features be conditionally compiled or enabled by default behavior, even if the associated flag does not appear in .config?