.TH VI 1
.SH NAME
5i, ki, vi, qi \- instruction simulators
.SH SYNOPSIS
.B vi
[
.I textfile
]
.br
.B vi
.I pid
.br
.B 5i
[
.I textfile
]
.br
.B 5i
.I pid
.br
.B ki
[
.I textfile
]
.br
.B ki
.I pid
.br
.B qi
[
.I textfile
]
.br
.B qi
.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 5i ,
.IR ki ,
and
.IR qi
are similar to
.I vi
but interpret ARM, SPARC, and PowerPC 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.