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.
       Programs running under vi execute about two hundred times slower than normal--but faster than single stepping under db.	Ki and xi are sim-
       ilar 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
       continuation.

       As a debugger vi offers more complete information than db(1).  Tracing can be performed at the level  of  instructions,	system	calls,	or
       function  calls.   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.  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 detailed 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  for-
       mats.

       Several extra commands allow extended tracing and printing of statistics:

       $t[0ics]
	      The t command controls tracing. Zero cancels all tracing options.

	      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)