On my macppc, the presence of /auto_upgrade.conf doesn't actually cause bsd.rd to pretend it's been netbooted. The file is present at the root of my disk, under /dev/wda0. The documentation in autoinstall(8) says that the presence of /auto_{upgrade,install}.conf tells bsd.rd to treat it like an autoinstall. So far my macppc boots bsd.rd, but stays at the prompt without doing a timeout of any kind or trying /auto_upgrade.conf, even if I do select Autoinstall at the prompt.
If I am to put /auto_upgrade.conf in the root of the file system in bsd.rd, how could I do so? If not, how could I use the automatic upgrade system without netbooting? Thank you