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iec(1)								       iec(1)



NAME

  iec -	Instruction Emulator Control

SYNOPSIS

  iec p	| s [value]

  iec p	| s [keyword]

OPTIONS

  The following	options	are used with the iec command:

  p   Sets or displays the current option setting for the parent process.

  s   Sets or displays the current option setting for the system.

  The following	keywords are used with the p option:

  reset
      Resets the current option	settings to the	default	settings for the
      parent process.

  noprint
      Does not print the instruction emulation warning message for the parent
      process.

  noemul
      Disables instruction emulation.  Any programs that attempt to execute
      instructions that	are not	implemented in the host	processor will
      receive the SIGILL (illegal instruction) signal.

  verbose
      Prints the instruction emulation warning messages	for all	instances of
      instruction emulation.  By default, a message is only printed for	the
      first instance.

  The following	keywords are used with the s option:

  reset
      Resets the current option	settings to the	default	settings for the sys-
      tem.

  noprint
      Does not print the instruction emulation warning message for the sys-
      tem.

  If value is not specified, the current option	setting	is displayed.  You
  can specify value as either 0	(zero) or 1 (one).  If value is	0 (zero), the
  option is turned on and messages are not displayed. If value is 1 (one),
  the option is	turned off and messages	are displayed.

  Keywords can be used singly or in any	combination.  However, the reset key-
  word overrides any other keywords that it is used with.

  Usually, the parent process is the shell.



DESCRIPTION

  Some processors in the Alpha processor family	do not implement all of	the
  instructions defined in the Alpha architecture.  The operating system	pro-
  vides	an instruction emulator	that permits all programs written for the
  Alpha	architecture to	run, regardless	of the Alpha processor being used.

  When the operating system encounters an instruction that is not implemented
  by the host processor, the default action is to emulate the instruction and
  print	a message informing the	user process that the emulation	has occurred.
  By default, the operating system prints a message only for the first
  instance of emulation, although it continues to emulate any other non-
  implemented instructions that	it encounters. The message has the form:
  "inst	emulated pid=nnn <prog_name> va=0xvirtual_addrpc=0xpc_addr
  inst=0xactual_instr".	Receiving this message tells you that your applica-
  tion will run	at less	than its optimal level of performance.	You may	wish
  to recompile your program to get better performance. For information on how
  to compile for a specific hardware platform, see the compiler	manpage	for
  the language you are using.

  In addition, the default action for the operating system is to not deliver
  a SIGILL signal to the parent	process	when an	emulated instruction is
  encountered.

  These	defaults are satisfactory for most users, but some users require a
  different behavior and want to specify their own Instruction Emulator	Con-
  trol (IEC).

  The iec command enables or disables the display of "inst emulated" mes-
  sages. The command sets or displays the IEC_NOPRINT, IEC_NOEMUL, and
  IEC_VERBOSE flags, as	defined	in setsysinfo(2).

RESTRICTIONS

  You must be superuser	to set the system option.

EXAMPLES

   1.  Both of the following commands disable messages for the parent pro-
       cess:
	    # iec p 0

	    # iec p noprint

   2.  Both of the following commands enable messages for the system:
	    # iec s 1

	    # iec s reset

   3.  The following command enables the printing of a message for each	emu-
       lated instruction:
	    # iec p verbose








SEE ALSO

  getsysinfo(2), setsysinfo(2)