iec(1)iec(1)NAMEiec - Instruction Emulator Control
SYNOPSISiec p | s [value]
iec p | s [keyword]
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
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.
Some processors in the Alpha processor family do not implement all of
the instructions defined in the Alpha architecture. The operating sys‐
tem provides an instruction emulator that permits all programs written
for the Alpha architecture to run, regardless of the Alpha processor
When the operating system encounters an instruction that is not imple‐
mented 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=0xvir‐
tual_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 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 Emulator
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).
You must be superuser to set the system option.
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 ALSOgetsysinfo(2), setsysinfo(2)iec(1)