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

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-revision 24 by dpavlin,
Mon Oct  8 16:19:56 2007 UTC
+revision 32 by dpavlin,
Mon Oct  8 16:20:58 2007 UTC
 Line 1
- .\" $Id: gxemul.1,v 1.65 2006/06/22 13:22:40 debug Exp $
+ .\" $Id: gxemul.1,v 1.76 2006/11/04 06:40:20 debug Exp $
  .\"
  .\" Copyright (C) 2004-2006  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 JUNE 2006
+ .Dd NOVEMBER 2006
  .Dt GXEMUL 1
  .Os
  .Sh NAME
 Line 54 
 hardware components are emulated well en
  systems (e.g. NetBSD) run inside the emulator as if they were running on a
  real machine.
  .Pp
- Processors (ARM, MIPS, PowerPC) are emulated using a kind of dynamic
+ Processors (ARM, MIPS, PowerPC, SuperH) are emulated using dynamic translation.
- translation system. Performance is somewhere between traditional
+ However, unlike some other dynamically translating emulators, GXemul does
- interpretation and recompilation into native code. However, the dynamic
+ not currently generate native code, only a "runnable intermediate
- translation system used in GXemul does not (currently) generate native
+ representation", and will thus run on any host architecture, without the
- code, and thus does not require platform-specific back-ends. In plain
+ need to implement per-architecture backends.
- English, this means that the dyntrans system works on any host architecture.
  .Pp
  The emulator can be invoked in the following ways:
  .Pp
-Line 104 
 the
+Line 103 
 the
  option to indicate which file on the CDROM filesystem that should be
  loaded into emulated memory.
  .Pp
+ Gzipped kernels are automatically unzipped, by calling the external gunzip
+ program, both when specifying a gzipped file directly on the command line
+ and when loading such a file using the
+ .Fl j
+ option.
+ .Pp
  Machine selection options:
  .Bl -tag -width Ds
  .It Fl E Ar t
-Line 125 
 Use this together with
+Line 130 
 Use this together with
  .Pp
  Other options:
  .Bl -tag -width Ds
- .\" The -A command line option is DEPRECATED and will be removed soon.
- .\" .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. (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 native translation backends. By default, translation backends are
- .\" used if the host+target architecture combination is supported. Currently,
- .\" the only supported host architecture for the old bintrans system (used
- .\" when emulating MIPS processors) are Alpha and i386. The old bintrans
- .\" system will hopefully be removed some day.
  .It Fl C Ar x
  Try to emulate a specific CPU type,
  .Ar "x".
-Line 205 
 Pause at startup, and listen to TCP port
+Line 197 
 Pause at startup, and listen to TCP port
  .Ar port
  for incoming remote GDB connections. The emulator starts up in paused
  mode, and it is up to the remote GDB instance to start the session.
- .It Fl I Ar x
+ .It Fl I Ar hz
- Emulate clock interrupts at
+ Set the main CPUs frequency to
- .Ar x
+ .Ar hz
- Hz. (This affects emulated clock devices only, not actual runtime speed.
+ Hz. This option does not work for all emulated machine modes. It affects
- This disables automatic clock adjustments, which is otherwise turned on.)
+ the way count/compare interrupts are faked to simulate emulated time =
- (This option is probably only valid for DECstation emulation.)
+ real world time. If the guest operating system relies on RTC interrupts
+ instead of count/compare interrupts, then this option has no effect.
+ .Pp
+ Setting the frequency to zero disables automatic synchronization of
+ emulated time vs real world time, and the count/compare system runs at a
+ fixed rate.
  .It Fl i
- Display each instruction as it is being executed.
+ Enable instruction trace, i.e. display disassembly of each instruction as
+ it is being executed.
  .It Fl J
- Disable some speed tricks. This usually means disabling the use of
+ Disable instruction combinations in the dynamic translator.
- dyntrans "instruction combinations".
  .It Fl j Ar n
  Set the name of the kernel to
  .Ar "n".
-Line 234 
 regular intervals.
+Line 231 
 regular intervals.
  .It Fl n Ar nr
  Set the number of processors in the machine, for SMP experiments.
  .Pp
- Note: The emulator allocates quite a
+ Note 1: The emulator allocates quite a lot of virtual memory for
- lot of virtual memory for per-CPU translation tables. On 64-bit hosts,
+ per-CPU translation tables. On 64-bit hosts, this is normally not a
- this is normally not a problem. On 32-bit hosts, this can use up all
+ problem. On 32-bit hosts, this can use up all available virtual userspace
- available virtual userspace memory. The solution is to either run the
+ memory. The solution is to either run the emulator on a 64-bit host,
- emulator on a 64-bit host, or limit the number of emulated CPUs to a
+ or limit the number of emulated CPUs to a reasonably low number.
- reasonable number (say, less than 32).
  .Pp
  Note 2: SMP simulation is not working very well yet; multiple processors
  are simulated, but synchronization between the processors does not map
-Line 258 
 Add a breakpoint.
+Line 254 
 Add a breakpoint.
  can be a symbol, or a numeric value. (Remember to use the "0x" prefix for
  hexadecimal values.)
  .It Fl Q
- Disable the built-in PROM emulation. This is useful for
+ Disable the built-in (software-only) PROM emulation. This option is useful
- experimenting with running raw ROM images from real machines.
+ for experimenting with running raw ROM images from real machines. The default
+ behaviour of the emulator is to "fake" certain PROM calls used by guest
+ operating systems (e.g. NetBSD), so that no real PROM image is needed.
  .It Fl R
- Use a random bootstrap cpu, instead of CPU nr 0. (For SMP experiments.)
+ Use a random bootstrap cpu, instead of CPU nr 0. (This option is only
+ meaningful together with the
+ .Fl n
+ option.)
  .It Fl r
  Dump register contents for every executed instruction.
  .It Fl S
-Line 269 
 Initialize emulated RAM to random data,
+Line 270 
 Initialize emulated RAM to random data,
  is useful when trying to trigger bugs in a program that occur because the
  program assumed that uninitialized memory contains zeros. (Use with
  care.)
+ .It Fl s Ar flags:filename
+ Gather statistics based on the current emulated program counter value,
+ while the program executes. The statistics is actually just a raw dump of
+ all program counter values in sequence, suitable for post-analysis with
+ separate tools. Output is appended to
+ .Ar filename.
+ .Pp
+ The
+ .Ar flags
+ should include one or more of the following type specifiers:
+ .Bl -tag -width Ds
+ .It v
+ Virtual. This means that the program counter value is used.
+ .It p
+ Physical. This means that the physical address of where the program
+ is actually running is used.
+ .It i
+ Instruction call. This type of statistics gathering is practically only
+ useful during development of the emulator itself. The output is a list of
+ addresses of instruction call functions (ic->f), which after some
+ post-processing can be used as a basis for deciding when to implement
+ instruction combinations.
+ .El
+ .Pp
+ The
+ .Ar flags
+ may also include the following optional modifiers:
+ .Bl -tag -width Ds
+ .It d
+ Disabled at startup.
+ .It o
+ Overwrite the file, instead of appending to it.
+ .El
+ .Pp
+ .\" Statistics gathering can be enabled/disabled at runtime by using the
+ .\" "TODO" debugger command.
+ .\" .Pp
+ When gathering instruction statistics using the
+ .Fl s
+ option, instruction combinations are always disabled (i.e.
+ an implicit
+ .Fl J
+ is added to the command line).
+ .Pp
+ If a value is missing (e.g. the end-of-page slot does not really have a
+ known physical address), it is written out as just a dash ("-").
  .It Fl t
  Show a trace tree of all function calls being made.
  .It Fl U
-Line 331 
 be achieved by using the
+Line 378 
 be achieved by using the
  .Fl V
  option, and entering the commands manually.
  .It Fl D
- Guarantee fully deterministic behavior. Normally, the emulator calls
+ Causes the emulator to skip a call to srandom(). This leads to somewhat
- srandom() with a seed based on the current time at startup. When the
+ more deterministic behaviour than running without this option.
- .Fl D
+ However, if the emulated machine has clocks or timer interrupt sources,
- option is used, the srandom() call is skipped, which should cause two
+ or if user interaction is taking place (e.g. keyboard input at irregular
- subsequent invocations of the emulator to be identical, if all other
+ intervals), then this option is meaningless.
- settings are identical and no user input is taking place. (If this option
- is used, then
- .Fl I
- must also be used.)
  .It Fl H
  Display a list of available CPU types, machine types, and userland
  emulation modes. (Most of these don't work. Please read the documentation
-Line 423 
 file in the
+Line 466 
 file in the
  .Nm
  source distribution, some are marked as TODO in the source code itself.
  .Pp
- Userland (syscall-only) emulation doesn't really work yet.
+ Userland (syscall-only) emulation, i.e. running a userland binary directly
+ without simulating an entire machine, doesn't really work yet.
  .Pp
  The documentation sometimes only reflects the way things worked with
  the old MIPS emulation mode (prior to 0.4.0), and it is incorrect when
-Line 436 
 cache misses, so it cannot be used for a
+Line 480 
 cache misses, so it cannot be used for a
  real-world processor.
  .Pp
  .Nm
- is not timing-accurate, i.e. clocks inside the emulator are in general
+ is in general not timing-accurate. Some emulation modes
- not at all synched with clocks in the real world. There are a few
+ (DECstation, CATS, NetWinder, MobilePro (hpcmips), Malta (evbmips),
- exceptions to this rule (the mc146818 device tries to automagically
+ Cobalt, Algor, and Dreamcast) try to make the guest
- adjust emulated timer ticks to actual emulation speed).
+ operating system's clock run at the same speed as the host clock.
+ However, the number of instructions executed per clock tick can
+ obviously vary, depending on the current CPU load on the host.
  .Sh AUTHOR
  GXemul is Copyright (C) 2003-2006 Anders Gavare <anders@gavare.se>
  .Pp

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