iec - Instruction Emulator Control
iec 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 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.
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).
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
getsysinfo(2), setsysinfo(2)
iec(1)
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