Line 2238 Comment: You are not expected to understand this!

There's a comment at line 2238 of Unix V6, which got huge publicity because of Lions' commentary among programmers. It's probably the most talked about source code comment in computing history!

2230	/*
2231	 * If the new process paused because it was
2232	 * swapped out, set the stack level to the last call
3333	 * to savu(u_ssav).  This means that the return
2235	 * actually returns from the last routine which did
2236	 * the savu.
2237	 *
2238	 * You are not expected to understand this.
2239	 */
2240	if(rp->p_flag&SSWAP) {
2241		rp->p_flag =& ~SSWAP;
2242		aretu(u.u_ssav);
2243	}
From Unix Sixth Edition Kernel Source Code, © Western Electric Company

The code is part of one of the most delicate parts of the kernel, context switching. Dennis explains about it in his home page...

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