term% cat index.txt VI(1) General Commands Manual VI(1)
NAME
vi, ki, xi - instruction simulators
SYNOPSIS
vi [ textfile ]
vi pid
ki [ textfile ]
ki pid
xi [ textfile ]
xi pid
DESCRIPTION
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. Pro‐
grams running under vi execute about two hundred times slower than nor‐
mal—but faster than single stepping under db. Ki and xi are similar to
vi but interpret SPARC and ATT3210 binaries. The following discussion
refers to vi but applies to the others as well.
Vi will simulate the execution of a named textfile. It will also make
a copy of an existing process with process id pid and simulate its con‐
tinuation.
As a debugger vi offers more complete information than db(1). Tracing
can be performed at the level of instructions, system calls, or func‐
tion calls. Vi allows breakpoints to be triggered when specified ad‐
dresses in memory are accessed. A report of instruction counts, load
delay fills and distribution is produced for each run. Vi simulates
the CPU's caches and MMU to assist the optimization of compilers and
programs.
The command interface mirrors the interface to db; see db(1) for a de‐
tailed description. Data formats and addressing are compatible with db
except for disassembly: vi offers only MIPS (db -mmipsco) mnemonics for
machine instructions. Ki offers both Plan 9 and Sun SPARC formats.
Several extra commands allow extended tracing and printing of statis‐
tics:
$t[0ics]
The t command controls tracing. Zero cancels all tracing op‐
tions.
i Enable instruction tracing
c Enable call tracing
s Enable system call tracing
$i[itsp]
The i command prints statistics accumulated by all code run in
this session.
i Print instruction counts and frequency.
p Print cycle profile.
t (Vi only) Print TLB and cache statistics.
s Print memory reference, working set and size statistics.
:b[arwe]
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 count (see db(1)) supplied to the command.
SOURCE
/sys/src/cmd/vi etc.
SEE ALSO
nm(1), db(1)
BUGS
The code generated by the compilers is well supported, but some unusual
instructions are unimplemented. Some Plan 9 system calls such as rfork
cause simulated traps. The floating point simulation makes assumptions
about the interpreting machine's floating point support. The floating
point conversions performed by vi may cause a loss of precision.
VI(1)