[TUHS] V6 UNIX main() oddness

Noel Chiappa jnc at mercury.lcs.mit.edu
Fri Jan 26 04:42:59 AEST 2018

So, while bringing up V6 on a hardware PDP-11/23 with an RK11 emulator using
an SD card for storage which Dave Bridgham and I are doing, I found this piece
of code in main() on V6 Unix:

	rootdir = iget(rootdev, ROOTINO);
	rootdir->i_flag =& ~ILOCK;
	u.u_cdir = iget(rootdev, ROOTINO);
	u.u_cdir->i_flag =& ~ILOCK;

I don't get why two separate calls to iget(), with the same arguments;
why not replace the second pair of lines with:

	u.u_cdir = rootdir;

What am I missing?


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