osf1 man page for iec

iec(1)							      General Commands Manual							    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: Sets or displays the current option setting for the parent process.  Sets or displays
       the current option setting for the system.

       The following keywords are used with the p option: Resets the current option settings to the default settings for the parent process.  Does
       not  print the instruction emulation warning message for the parent process.  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.   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: Resets the current option settings to the default settings for  the  system.	 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 pro-
       cessor 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 mes-
       sage 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 bet-
       ter  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  instruc-
       tion is encountered.

       These  defaults are satisfactory for most users, but some users require a different behavior and want to specify their own Instruction Emu-
       lator 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
       Both of the following commands disable messages for the parent process: # iec p 0

       # iec p noprint Both of the following commands enable messages for the system: # iec s 1

       # iec s reset The following command enables the printing of a message for each emulated instruction: # iec p verbose

SEE ALSO
       getsysinfo(2), setsysinfo(2)

																	    iec(1)