Being a little curious about Bell Lab's Plan 9 I tried to get the
installation/demo CD running under qemu. The major stumbling block I
encountered was that the IDE emulation wasn't properly detected. A
little bit of debugging revealed that Plan 9 was relying on an
an IDE feature that hasn't been implemented in qemu.
Adding some very shoddy (and almost certainly wrong) support for
WIN_DIAGNOSE to ide_ioport_write in hw/ide.c was enough to get it to boot
and run the live version. Is anyone likely to provide a proper
implementation? I'd do it myself, but the (draft) ATA specs I had a look
through appeared to have some oddities I'd rather not have to deal with,
given that I've never done any ATA work before.