> Ok, I've not built a boot floppy before so I've probably missed
> something.  Yet I get.

> /dev/rvnd0a: open: Device not configured *** Error code 1

Thanks to all who pointed out that updating disktab would solve this.
I'm now failing because a 1.2M floppy is not big enough.

Also I found the following patch handy to ensure that runing
make(1) again after a failure will not die due to vnd0 being busy.
The dd command also needs to be changed to produce a 1.4M floppy image.

I'm updating my sources now - if this is still needed I'll PR it.

*** distrib/i386/floppies/ramdisk/Makefile.old     Wed Jul 30 21:25:09 1997
--- distrib/i386/floppies/ramdisk/Makefile       Mon Nov 10 09:18:29 1997
***************
*** 36,41 ****
--- 36,43 ----
        sed "s/@@VERSION@@/${VER}/" < ${.ALLSRC} > ${.TARGET}
  
  all: ${AUXTARGETS} ${CBIN} 
+       -umount ${MOUNT_POINT}
+       -vnconfig -u ${VND_CDEV}
        dd if=/dev/zero of=${IMAGE} count=2880
        vnconfig -t ${DISKTYPE} -v -c ${VND_CDEV} ${IMAGE}
        disklabel -rw ${VND_CDEV} ${DISKTYPE}
*** distrib/i386/floppies/bootfloppy-common/Makefile.inc.old     Wed Jul 30 21:25:09 1997
--- distrib/i386/floppies/bootfloppy-common/Makefile.inc       Mon Nov 10 09:18:29 1997
***************
*** 19,25 ****
          printf "xxx: .MAKE\n\t@echo \$${.OBJDIR}/ramdisk-${REV}.fs\n" | \
        ${MAKE} -s -f-
  
! DISKTYPE=     floppy5
  
  # Some reasonable values for the -i parameter to newfs are:
  #
--- 19,25 ----
          printf "xxx: .MAKE\n\t@echo \$${.OBJDIR}/ramdisk-${REV}.fs\n" | \
        ${MAKE} -s -f-
  
! DISKTYPE=     floppy3
  
  # Some reasonable values for the -i parameter to newfs are:
  #
***************
*** 31,37 ****
  CLEANFILES+=  netbsd.ram.gz
  
  all:  netbsd.ram.gz
!       dd if=/dev/zero of=${IMAGE} bs=100k count=12
        vnconfig -t ${DISKTYPE} -v -c ${VND_CDEV} ${IMAGE}
        disklabel -rw ${VND_CDEV} ${DISKTYPE}
        newfs -m 0 -o space -i ${INO_BYTES} -c 80 ${VND_RDEV} ${DISKTYPE}
--- 31,39 ----
  CLEANFILES+=  netbsd.ram.gz
  
  all:  netbsd.ram.gz
!       -umount ${MOUNT_POINT}
!       -vnconfig -u ${VND_CDEV}
!       dd if=/dev/zero of=${IMAGE} count=2880
        vnconfig -t ${DISKTYPE} -v -c ${VND_CDEV} ${IMAGE}
        disklabel -rw ${VND_CDEV} ${DISKTYPE}
        newfs -m 0 -o space -i ${INO_BYTES} -c 80 ${VND_RDEV} ${DISKTYPE}