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Command: iec | Section: 1 | Source: Digital UNIX | File: iec.1.gz
iec(1) General Commands Manual iec(1)
NAME
iec - Instruction Emulator Control
SYNOPSIS
iec p | s [value]
iec p | s [keyword]
FLAGS
The following flags are used with the iec command: Sets or displays the
current flag setting for the parent process. Sets or displays the cur-
rent flag setting for the system.
The following keywords are used with the p flag: Resets the current
flag 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 re-
ceive 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 flag: Resets the current
flag 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 flag setting is displayed. You
can specify value as either 0 (zero) or 1 (one). If value is 0 (zero),
the flag is turned on and messages are not displayed. If value is 1
(one), the flag 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 sys-
tem 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 imple-
mented by the host processor, the default action is to emulate the in-
struction and print a message informing the user process that the emu-
lation has occurred. By default, the operating system prints a message
only for the first instance of emulation, although it continues to emu-
late any other non-implemented instructions that it encounters. The
message has the form: "inst emulated pid=nnn <prog_name> va=0xvir-
tual_addr pc=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 de-
liver 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
Control (IEC).
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).
RESTRICTIONS
You must be superuser to set the system flag.
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 emu-
lated instruction: # iec p verbose
RELATED INFORMATION
getsysinfo(2), setsysinfo(2) delim off
iec(1)