message for Bruces changes:
>From: bde@kralizec.zeta.org.au (Bruce Evans)
>Subject: fixes for fd driver
I think I've fixed some bugs in the 0.2.4 fd driver.
1. The main cause of hangs was that there was no timeout for seeks. So
attempting i/o with no floppy in the drive hung iff a seek was required.
2. Opens of unattached drives were allowed. The kernel usually paniced
soon after due to a bad pointer.
3. Some timeout functions ran at splclock() instead of splbio(). This
may not have mattered.
4. The state machine was left in a funny state after a timeout.
5. Some function headers were new-style.
6. I picked up some code posted the other day to implement label ioctls.
Now `disklabel fd0' works. See a comment for how to modify conf.c.
fe3380ea19