TH VI 1
SH NAME
0i, 5i, 9i, ki, vi, xi \- instruction simulators
SH SYNOPSIS
B vi
[
I textfile
]
br
B vi
I pid
br
B 0i
[
I textfile
]
br
B 0i
I pid
br
B 5i
[
I textfile
]
br
B 5i
I pid
br
B 9i
[
I textfile
]
br
B 9i
I pid
br
B ki
[
I textfile
]
br
B ki
I pid
br
B xi
[
I textfile
]
br
B xi
I pid
SH DESCRIPTION
I Vi
simulates the execution of a MIPS binary in
a Plan 9 environment.
It has two main uses: as
a debugger and as a statistics gatherer.
Programs running under
I vi
execute about two hundred times
slower than normal\(embut faster than
single stepping under
IR db .
IR 0i ,
IR 5i ,
IR 9i ,
IR ki,
and
I xi
are similar to
I vi
but interpret little-endian MIPS, ARM 7500, AMD2900, SPARC, and ATT3210 binaries.
The following discussion refers to
I vi
but applies to the others
as well.
PP
I Vi
will simulate the execution of a named
IR textfile .
It will also make a copy of an existing process with process id
I pid
and simulate its continuation.
PP
As a debugger
I vi
offers more complete information
than
IR db (1).
Tracing can be performed at the level of instructions,
system calls, or function calls.
I Vi
allows breakpoints to be triggered when specified addresses
in memory are accessed.
A report of instruction counts,
load delay fills and distribution is produced for
each run.
I Vi
simulates the CPU's caches and MMU
to assist the optimization of compilers and programs.
PP
The command interface mirrors the interface to
IR db ;
see
IR db (1)
for a detailed description.
Data formats and addressing are compatible with
I db
except
for disassembly:
I vi
offers only MIPS
RB ( db
BR -mmipsco )
mnemonics for
machine instructions.
I Ki
offers both Plan 9 and Sun SPARC formats.
PP
Several extra commands allow
extended tracing and printing of statistics:
TP
BR $t [ 0ics ]
The
I t
command controls tracing. Zero cancels all tracing
options.
RS
TP
B i
Enable instruction tracing
TP
B c
Enable call tracing
TP
B s
Enable system call tracing
RE
TP
BR $i [ itsp ]
The
B i
command prints statistics accumulated by
all code run in this session.
RS
TP
B i
Print instruction counts and frequency.
TP
B p
Print cycle profile.
TP
B t
RI ( Vi
only) Print TLB and cache statistics.
TP
B s
Print memory reference, working set and size statistics.
RE
TP
BR :b [ arwe ]
I Vi
allows breakpoints to be set on any memory location.
These breakpoints monitor when a location is
accessed, read, written, or equals a certain value.
For equality the compared value is the
I count
(see
IR db (1))
supplied to the command.
SH SOURCE
B /sys/src/cmd/vi
etc.
SH "SEE ALSO"
IR nm (1),
IR db (1)
SH BUGS
The code generated by
the compilers
is well supported, but some unusual instructions are unimplemented.
Some Plan 9 system calls such as
I rfork
cause simulated traps.
The floating point simulation makes assumptions about the interpreting
machine's floating point support. The floating point conversions performed
by
I vi
may cause a loss of precision.
