Comment by adrian_b

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Using nolibc is fine when you compile it together with the kernel.

The parent article is about a C header that you can use to compile your program independently of the source files of the Linux kernel.

Even the presence of the Linux kernel sources on your computer is not enough to enable the compilation of a program that uses directly the syscalls, as the raw sources do not contain any suitable header. You must first compile the kernel with the desired configuration, because header files are selected or auto-generated accordingly. That is enough for nolibc, which lives in the kernel source tree, but it would still be difficult to identify which are the header files that could be used to compile an external program.

Moreover, including Linux header files in your program is an extremely bad idea, because they are not stable. It is frequent that a minor version increase of the Linux kernel breaks the "#include" directives of external programs (such as out-of-tree device drivers), because items are moved between headers or some headers disappear and other headers appear.