The long story of #191038 finally concluded that the only need is for login man page to mention that /etc/nologin can be a symbolic link for people who want to try keeping a read-only /etc
Tomasz, please find attahced a patch for upstream CVS's login man page XML source. I just added a mention about this file OK for being a symlink. --
--- login.1.xml.ori 2005-05-24 19:06:01.000000000 +0200 +++ login.1.xml 2005-05-26 04:09:33.695634315 +0200 @@ -172,6 +172,12 @@ <filename>/etc/nologin</filename> - prevent non-root users from logging in <!-- .br --> + (can be a symbolic link to another + <!-- .br --> + file for users wanting to use a + <!-- .br --> + read-only root filesystem) + <!-- .br --> <filename>/etc/ttytype</filename> - list of terminal types <!-- .br --> <emphasis remap='I'>$HOME/.hushlogin</emphasis> - suppress printing