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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
      system.

  noprint
      Does not print the instruction emulation warning message for the
      system.

  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
  keyword 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
  provides 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
  application 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
  Control (IEC).

  The iec command enables or disables the display of "inst emulated"
  messages. 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
       process:
	    # 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
       emulated instruction:
	    # iec p verbose

SEE ALSO
  getsysinfo(2), setsysinfo(2)

Index for Section 1

Alphabetical listing for I

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