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NAME    [Toc]    [Back]

       iec - Instruction Emulator Control

SYNOPSIS    [Toc]    [Back]

       iec p | s [value]

       iec p | s [keyword]

OPTIONS    [Toc]    [Back]

       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

       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    [Toc]    [Back]

       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    [Toc]    [Back]

       You must be superuser to set the system option.

EXAMPLES    [Toc]    [Back]

       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    [Toc]    [Back]

       getsysinfo(2), setsysinfo(2)

[ Back ]
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