overrides file or directory

If you need to set up devices or options that are specific to your particular system configuration, create an overrides file or directory under /etc/system/enum.

The enumerator includes the overrides file or directory last and adds any definitions in it to the set that enum-devices works with. If the overrides file has something that a previously included file also has, the later definition wins. For example:

• If you want to stop a particular device from running, or change how it starts, create a /etc/system/enum/overrides file and add a device(…) entry for the device:

  device(pci, ven=1234, dev=2000)
  device(pci, ven=1234, dev=2001)
      requires( $(IOPKT_CMD), )
      uniq(netnum, devn-en, 0)
      mount(-Tio-pkt  /lib/dll/devn-pcnet.so, "/dev/io-net/en$(netnum)")
  
  device(pci, ven=1234, dev=2002)
  device(pci, ven=1234, dev=2003)
    

  The first block of this code specifies to do the following if the enumerator detects devices 2000 and 2001 from vendor 1234:

  1. If io-pkt* isn't running, start it. IOPKT_CMD is a macro, defined in /etc/system/enum/include/net, that specifies the default io-pkt* command line.
  2. Set netnum to the next unique network interface device number, starting at 0.
  3. Mount the PCNET driver into io-pkt*.

  The second block of code tells the enumerator to do nothing if it detects devices 2002 or 2003 from vendor 1234.

  Note: When you add device entries to prevent devices from being enumerated, make sure that there aren't any action clauses after them. Any group of actions clauses found after any single or set of device entries is used for those devices. Place these device entries at the end of your overrides configuration file.
• If you want to change the way the enumerator starts TCP/IP, you have to override the definition of the basic io-pkt* command that's defined in /etc/systems/enum/include/net. By default, the command is:

  io-pkt-v4-hc -ptcpip
    

  If you want to enable IPSec, add this code to your overrides file:

  all
          set(IOPKT_CMD, io-pkt-v4-hc -ptcpip ipsec)