The following parameters should be tunable at compile time. Some of them
  exist as sysctls too.
  
  This is far from complete
  
  Item			Description
  ----------------------------------------------------------------------------
  MAX_LINKS		Maximum number of netlink minor devices. (1-32)
  RIF_TABLE_SIZE		Token ring RIF cache size (tunable)
  AARP_HASH_SIZE		Size of Appletalk hash table (tunable)
  AX25_DEF_T1		AX.25 parameters. These are all tunable via
  AX25_DEF_T2		SIOCAX25SETPARMS
  AX25_DEF_T3		T1-T3,N2 have the meanings in the specification
  AX25_DEF_N2
  AX25_DEF_AXDEFMODE	8 = normal 128 is PE1CHL extended
  AX25_DEF_IPDEFMODE	'D' - datagram  'V' - virtual connection
  AX25_DEF_BACKOFF	'E'xponential 'L'inear
  AX25_DEF_NETROM		Allow netrom 1=Y
  AX25_DF_TEXT		Allow PID=Text 1=Y
  AX25_DEF_WINDOW		Window for normal mode
  AX25_DEF_EWINDOW	Window for PE1CHL mode
  AX25_DEF_DIGI		1 for inband 2 for cross band 3 for both
  AX25_DEF_CONMODE	Allow connected modes 1=Yes
  AX25_ROUTE_MAX		AX.25 route cache size - no currently tunable
  Unnamed (16)		Number of protocol hash slots (tunable)
  DEV_NUMBUFFS		Number of priority levels (not easily tunable)
  Unnamed (300)		Maximum packet backlog queue (tunable)
  MAX_IOVEC		Maximum number of iovecs in a message (tunable)
  MIN_WINDOW		Offered minimum window (tunable)
  MAX_WINDOW		Offered maximum window (tunable)
  MAX_HEADER		Largest physical header (tunable)
  MAX_ADDR_LEN		Largest physical address (tunable)
  SOCK_ARRAY_SIZE		IP socket array hash size (tunable)
  IP_MAX_MEMBERSHIPS	Largest number of groups per socket (BSD style) (tunable)
  16			Hard coded constant for amount of room allowed for
  			cache align and faster forwarding (tunable)
  IP_FRAG_TIME		Time we hold a fragment for. (tunable)
  PORT_MASQ_BEGIN		First port reserved for masquerade (tunable)
  PORT_MASQ_END		Last port used for masquerade	(tunable)
  MASQUERADE_EXPIRE_TCP_FIN	Time we keep a masquerade for after a FIN
  MASQUERADE_EXPIRE_UDP	Time we keep a UDP masquerade for (tunable)
  MAXVIFS			Maximum mrouted vifs (1-32)
  MFC_LINES		Lines in the multicast router cache (tunable)
  
  NetROM parameters are tunable via an ioctl passing a struct
  
  4000			Size a Unix domain socket malloc falls back to 
  			(tunable) should be 8K - a bit for 8K machines like
  			the ALPHA