| AUTOCONF(4) | Device Drivers Manual (vax) | AUTOCONF(4) | 
autoconf —
On the VAX, devices in NEXUS slots are normally noted, thus memory controllers, UNIBUS and MASSBUS adaptors. Devices which are not supported which are found in NEXUS slots are noted also. The Q-bus on the MICROVAX is configured in the same way as the UNIBUS.
MASSBUS devices are located by a very deterministic procedure since MASSBUS space is completely probe-able. If devices exist which are not configured they will be silently ignored; if devices exist of unsupported type they will be noted.
UNIBUS devices are located by probing to see if their control-status registers respond. If not, they are silently ignored. If the control status register responds but the device cannot be made to interrupt, a diagnostic warning will be printed on the console and the device will not be available to the system.
Normally, the system uses the disk from which it was loaded as the
    root filesystem. If that is not possible, a generic system will pick its
    root device as the “best” available device (MASSBUS disks are
    better than SMD UNIBUS disks are better than RK07s; the device must be drive
    0 to be considered). If such a system is booted with the
    RB_ASKNAME option (see
    reboot(2)), then the name
    of the root device is read from the console terminal at boot time, and any
    available device may be used.
tr%d’ (the NEXUS slot number).
      NetBSD will call it
      ‘mba%d’.tr%d’
      (the NEXUS slot number). NetBSD will call it
      ‘uba%d’.tr%d’ (the NEXUS slot number).
      NetBSD will call it
      ‘mcr%d’.%s%d’ will look like
      “hp0”, for tape formatters like
      “ht1”. The drive number comes from
      the unit plug on the drive or in the TM formatter (not
      on the tape drive; see below).tu0
      at ht0 slave 0”, where
      “tu0” is the name for the tape
      device and “ht0” is the name for the
      formatter. A tape slave was found on the tape formatter at the indicated
      drive number (on the front of the tape drive).
      UNIX will call the device, e.g.,
      “tu0”.%s%d’, e.g.
      “dz0” was found on
      ‘uba%d’ at control-status register
      address ‘%o’ and with device vector
      ‘%o’. The device interrupted at
      priority level ‘%x’.up0
      at sc0 slave 0”, where
      “up0” is the name of a disk drive
      and “sc0” is the name of the
      controller. Analogous to MASSBUS case.autoconf feature appeared in
  4.1BSD.
| February 17, 2017 | NetBSD 10.0 |