Indeed, you have to draw a line somewhere. Do you explain (1) 2+2, (2) user/kernel space, (3) what a _compat usually is for or (4) what this particular _compat

Indeed, you have to draw a line somewhere. Do you explain (1) 2+2, (2) user/kernel space, (3) what a _compat usually is for or (4) what this particular _compat does? I for one would draw the line before (4). The original developer drew it after. If I would explain API conventions I would draw it before (3) but crypto _API_ for example has the line after (4). And there are appropriate places for (1) and (2) also. The point is, you address to some audience. But even if the code is clean, a newcomer will have a hard time getting up to speed if he has no idea about the context. The way I see it, for some parts of the kernel, either the code is too precious to be touched or the maintainers do not have any interest in explaining it to an outsider. It's like they are loosing knowledge by sharing. Think new comers. How can you make them contribute? Or maybe the barrier to entry is high enough on purpose?