/[gxemul]/trunk/man/gxemul.1

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-revision 14 by dpavlin,
Mon Oct  8 16:18:51 2007 UTC
+revision 20 by dpavlin,
Mon Oct  8 16:19:23 2007 UTC
 Line 1
- .\" $Id: gxemul.1,v 1.33 2005/10/07 22:45:34 debug Exp $
+ .\" $Id: gxemul.1,v 1.39 2005/11/23 22:03:25 debug Exp $
  .\"
  .\" Copyright (C) 2004-2005  Anders Gavare.  All rights reserved.
  .\"
 Line 29
  .\" This is a minimal man page for GXemul. Process this file with
  .\"     groff -man -Tascii gxemul.1    or    nroff -man gxemul.1
  .\"
- .Dd OCTOBER 2005
+ .Dd NOVEMBER 2005
  .Dt GXEMUL 1
  .Os
  .Sh NAME
 Line 50
  is an experimental instruction-level machine emulator. Several
  emulation modes are available. In some modes, processors and surrounding
  hardware components are emulated well enough to let unmodified operating
- systems (e.g. NetBSD) run as if they were running on a real machine.
+ systems (e.g. NetBSD) run inside the emulator as if they were running on a
+ real machine.
  .Pp
  The processor architecture best emulated by GXemul is MIPS, but other
- architectures are also partially emulated.
+ architectures (ARM and PowerPC) are also partially emulated.
+ .Pp
+ MIPS processors are emulated either using a simple type of binary
+ translator (on Alpha and i386 hosts), or using traditional slow
+ interpretation (all other hosts, including amd64 machines running in
+-bit mode).
+ .Pp
+ Non-MIPS processors are emulated using a newer dynamic
+ translation system (called dyntrans in the rest of this man page);
+ dyntrans does not require any host-specific code, so it should work on any
+ platform. Performance is somewhere between binary translation and
+ traditional interpretation.
  .Pp
  There are three ways to invoke the emulator:
  .Pp
-Line 121 
 Other options:
+Line 133 
 Other options:
  .It Fl A
  Disable load/store alignment checks in some cases. This might give a small
  increase in performance, but the emulator will not run correctly if the
- emulated code actually tries to do unaligned loads or stores.
+ emulated code actually tries to do unaligned loads or stores. (This option
+ is only meaningful when emulating MIPS CPUs, when the host architecture is
+ Alpha or i386, and binary translation is enabled.)
  .It Fl B
  Disable dynamic binary translation. By default, bintrans
  will be turned on if the host+target architecture combination is
- supported.
+ supported. Currently, the only supported target architecture for bintrans
+ is MIPS, and the supported host architectures are Alpha and i386.
  .It Fl C Ar x
  Try to emulate a specific CPU type,
  .Ar "x".
-Line 184 
 This disables automatic clock adjustment
+Line 199 
 This disables automatic clock adjustment
  .It Fl i
  Display each instruction as it is being executed.
  .It Fl J
- Disable some speed tricks.
+ Disable some speed tricks. For MIPS emulation, these are mostly
+ timing-related. For non-MIPS emulation (i.e. those modes using dyntrans),
+ this flag disables the use of "instruction combinations".
  .It Fl j Ar n
  Set the name of the kernel to
  .Ar "n".
-Line 209 
 Set nr of CPUs (for SMP experiments).
+Line 226 
 Set nr of CPUs (for SMP experiments).
  Force a "netboot" (tftp instead of disk), even when a disk image is
  present (for DECstation, SGI, and ARC emulation).
  .It Fl o Ar arg
- Set the boot argument (for DEC, ARC, or SGI emulation).
+ Set the boot argument (mostly useful for DEC, ARC, or SGI emulation).
  Default
  .Ar arg
- for DEC is "-a", for ARC "-aN".
+ for DEC is "-a", for ARC/SGI it is "-aN", and for CATS it is "-A".
  .It Fl p Ar pc
  Add a breakpoint. (Remember to use the "0x" prefix for hex.)
  .It Fl Q
-Line 241 
 Scale down framebuffer windows by
+Line 258 
 Scale down framebuffer windows by
  .Ar n
  x
  .Ar n
- times.
+ times. This option is useful when emulating a very large framebuffer, and
+ the actual display is of lower resolution. If
+ .Ar n
+ is negative, then there will be no scaledown, but emulation of certain
+ graphic controllers will be scaled up
+ by
+ .Ar -n
+ times instead. E.g. Using
+ .Ar -2
+ with VGA text mode emulation will result in 80x25 character cells rendered
+ in a 1280x800 window, instead of the normal resolution of 640x400.
  .It Fl y Ar x
  Set max_random_cycles_per_chunk to
  .Ar x
-Line 290 
 Force the single-step debugger to be ent
+Line 317 
 Force the single-step debugger to be ent
  .It Fl q
  Quiet mode; this suppresses startup messages.
  .It Fl s
- Show opcode usage statistics after the simulation.
+ For MIPS emulation: Show opcode usage statistics after the simulation.
+ For non-MIPS emulation (i.e. using dyntrans): Save statistics to a file at
+ regular intervals of which physical addresses that were executed.
  .It Fl V
  Start up in the single-step debugger, paused.
  .It Fl v
-Line 346 
 terrible than running without it.
+Line 375 
 terrible than running without it.
  .Pp
  Userland (syscall-only) emulation doesn't really work yet.
  .Pp
+ Emulation of MIPS CPUs is done differently from other emulation modes; the
+ documentation sometimes only reflects the way things work with MIPS
+ emulation, and it is incorrect when applied to e.g. ARM emulation.
+ .Pp
  .Nm
  does not simulate individual pipe-line stages or penalties caused by
  branch-prediction misses or cache misses, so it cannot be used for

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