trunk/man/gxemul.1

.\" $Id: gxemul.1,v 1.39 2005/11/23 22:03:25 debug Exp $
.\"
.\" Copyright (C) 2004-2005  Anders Gavare.  All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions are met:
.\"
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. The name of the author may not be used to endorse or promote products
.\"    derived from this software without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\" 
.\" 
.\" This is a minimal man page for GXemul. Process this file with
.\"     groff -man -Tascii gxemul.1    or    nroff -man gxemul.1
.\"
.Dd NOVEMBER 2005
.Dt GXEMUL 1
.Os
.Sh NAME
.Nm gxemul
.Nd an experimental machine emulator
.Sh SYNOPSIS
.Nm
.Op machine, other, and general options
.Op file Ar ...
.Nm
.Op general options
.Ar @configfile
.Nm
.Op userland, other, and general options
.Ar file Op Ar args ...
.Sh DESCRIPTION
.Nm
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 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 (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 
64-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
1. When emulating a complete machine, configuration options can be entered
directly on the command line.
.Pp
2. Options can be read from a configuration file.
.Pp
3. When emulating a userland environment (syscall-only emulation, not
emulating complete machines), then the program name and its argument
should be given on the command line. (This mode doesn't really work yet.)
.Pp
The easiest way to use the emulator is to supply settings directly on the 
command line. The most important thing you need to supply is the
file argument. This is the name of a binary file (an ELF, a.out, COFF/ECOFF,
SREC, or a raw binary image) which you wish to run in the emulator. This file
might be an operating system kernel, or perhaps a ROM image file.
.Pp
If more than one filename is supplied, all files are loaded into memory, 
and the entry point (if available) is taken from the last file.
.Pp
Apart from the name of a binary file, it is also necessary to select
which specific emulation mode to use. For example, a MIPS-based machine
from DEC (a DECstation) is very different from a MIPS-based machine
from SGI. Use
.Nm
.Fl H
to get a list of available emulation modes.
.Pp
There are two exceptions to the normal invocation usage mentioned above.
The first is for DECstation emulation: if you have a bootable
DECstation harddisk or CDROM image, then just supplying the diskimage via 
the
.Fl d
option is sufficient. (The filename of the kernel can then be 
skipped, as the emulator runs the bootblocks from the diskimage directly and 
doesn't need the kernel as a separate file.)
The second is if you supply an ISO9660 CDROM disk image. You may then use 
the
.Fl j
option to indicate which file on the CDROM filesystem that should be 
loaded into emulated memory.
.Pp
Machine selection options:
.Bl -tag -width Ds
.It Fl E Ar t
Try to emulate machine type
.Ar "t".
This option is not always needed, if the
.Fl e
option uniquely selects a machine.
(Use
.Fl H
to get a list of types.)
.It Fl e Ar st
Try to emulate machine subtype
.Ar "st".
Use this together with
.Fl E .
(This option is not always needed, if a machine type has no subtypes.)
.El
.Pp
Other options:
.Bl -tag -width Ds
.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 dynamic binary translation. By default, bintrans
will be turned on if the host+target architecture combination is 
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".
This overrides the default CPU type for the machine being emulated.
(Use
.Fl H
to get a list of available CPU types.)
.It Fl d Ar name
Add
.Ar name
as a disk image. By adding one or more modifier characters and then a
colon (":") as a prefix to
.Ar "name",
you can modify the way the disk image is treated. Available modifiers are:
.Bl -tag -width Ds
.It b
Specifies that this is a boot device.
.It c
CD-ROM.
.It d
DISK (this is the default).
.It f
FLOPPY.
.It gH;S;
Override the default geometry; use H heads and S sectors-per-track.
(The number of cylinders is calculated automatically.)
.It i
IDE.
.It r
Read-only (don't allow changes to be written to the file).
.It s
SCSI (this is the default for most machine types).
.It t
Tape.
.It 0-7
Force a specific ID number.
.El
.Pp
Unless otherwise specified, filenames ending with ".iso" or ".cdr" are 
assumed to be CDROM images. Most others are assumed to be disks. Depending
on which machine is being emulated, the default for disks can be either 
SCSI or IDE. Some disk images that are very small are assumed to be floppy 
disks. (If you are not happy with the way a disk image is detected, then 
you need to use explicit prefixes to force a specific type.)
.Pp
For floppies, the gH;S; prefix is ignored. Instead, the number of 
heads and cylinders are assumed to be 2 and 80, respectively, and the 
number of sectors per track is calculated automatically. (This works for 
720KB, 1.2MB, 1.44MB, and 2.88MB floppies.)
.It Fl I Ar x
Emulate clock interrupts at
.Ar x
Hz. (This affects emulated clock devices only, not actual runtime speed.
This disables automatic clock adjustments, which is otherwise turned on.)
(This option is probably only valid for DECstation emulation.)
.It Fl i
Display each instruction as it is being executed.
.It Fl J
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".
When booting from an ISO9660 filesystem, the emulator will try to boot 
using this file. (In some emulation modes, eg. DECstation, this name is passed 
along to the boot program. Useful names are "bsd" for OpenBSD/pmax, 
or "vmunix" for Ultrix.)
.It Fl M Ar m
Emulate
.Ar m
MBs of physical RAM. This overrides the default amount of RAM for the 
selected machine type.
.It Fl m Ar nr
Run at most
.Ar nr
instructions (on any cpu).
.It Fl N
Display nr of instructions/second average, at regular intervals.
.It Fl n Ar nr
Set nr of CPUs (for SMP experiments).
.It Fl O
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 (mostly useful for DEC, ARC, or SGI emulation).
Default
.Ar arg
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
Disable the built-in PROM emulation. This is useful for running raw ROM
images from real machines.
.It Fl R
Use a random bootstrap cpu, instead of CPU nr 0. (For SMP experiments.)
.It Fl r
Dump register contents for every executed instruction.
.It Fl S
Initialize the emulated RAM to random data, instead of zeroes.
.It Fl T
Enter the single-step debugger on unimplemented memory accesses.
.It Fl t
Show a trace tree of all function calls being made.
.It Fl U
Enable slow_serial_interrupts_hack_for_linux.
.It Fl X
Use X11.
.It Fl x
Open up new xterms for emulated serial ports. (Default is to open up 
xterms when using configuration files, but not when starting an 
emulation with settings directly on the command line.)
.It Fl Y Ar n
Scale down framebuffer windows by
.Ar n
x
.Ar n
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
(experimental).
.It Fl Z Ar n
Set the number of graphics cards, for emulating a dual-head or tripple-head
environment. (Only for DECstation emulation so far.)
.It Fl z Ar disp
Add
.Ar disp
as an X11 display to use for framebuffers.
.El
.Pp
Userland options:
.Bl -tag -width Ds
.It Fl u Ar emul-mode
Userland-only (syscall) emulation. (Use
.Fl H
to get a list of available emulation modes.) Some (but not all) of the
options listed under Other options above can also be used with userland
emulation.
.El
.Pp
General options:
.Bl -tag -width Ds
.It Fl D
Guarantee fully deterministic behavior. Normally, the emulator calls
srandom() with a seed based on the current time at startup. When the
.Fl D
option is used, the srandom() call is skipped, which should cause two 
subsequent invocations of the emulator to be identical, if all other 
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
included in the
.Nm
distribution for details on which modes that actually work.)
.It Fl h
Display a list of all available command line options.
.It Fl K
Force the single-step debugger to be entered at the end of a simulation.
.It Fl q
Quiet mode; this suppresses startup messages.
.It Fl s
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
Verbose debug messages.
.El
.Pp
Configuration file startup:
.Bl -tag -width Ds
.It @ Ar configfile
Start an emulation based on the contents of
.Ar "configfile".
.El
.Pp
For more information, please read the documentation in the doc/
subdirectory of the
.Nm
distribution.
.Sh EXAMPLES
The following command will start NetBSD/pmax on an emulated DECstation 
5000/200 (3MAX):
.Pp
.Dl "gxemul -e 3max -d nbsd_pmax.img"
.Pp
nbsd_pmax.img should be a raw disk image containing a bootable 
NetBSD/pmax filesystem.
.Pp
The following command will start an emulation session based on settings in 
the configuration file "mysession". The -v option tells gxemul to be
verbose.
.Pp
.Dl "gxemul -v @mysession"
.Pp
If you have compiled the small Hello World program mentioned in the
.Nm
documentation, the following command will start up an
emulated test machine in "paused" mode:
.Pp
.Dl "gxemul -E testmips -V hello_mips"
.Pp
(Paused mode means that you enter the interactive single-step debugger
directly at startup, instead of launching the Hello World program.)
.Pp
Please read the documentation for more details.
.Sh BUGS
There are many bugs. Some of the known bugs are listed in the BUGS
file in the
.Nm
source distribution, some are indirectly mentioned in the TODO file,
and some are mentioned in the source code itself.
.Pp
The binary translation subsystem is really terrible, but it is less
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
accurate simulation of any actual real-world processor.
.Pp
.Nm
is not timing-accurate.
.Sh AUTHOR
Anders Gavare <anders@gavare.se>
.Pp
See http://gavare.se/gxemul/ for more information.
1	.\" $Id: gxemul.1,v 1.39 2005/11/23 22:03:25 debug Exp $
2	.\"
3	.\" Copyright (C) 2004-2005 Anders Gavare. All rights reserved.
4	.\"
5	.\" Redistribution and use in source and binary forms, with or without
6	.\" modification, are permitted provided that the following conditions are met:
7	.\"
8	.\" 1. Redistributions of source code must retain the above copyright
9	.\" notice, this list of conditions and the following disclaimer.
10	.\" 2. Redistributions in binary form must reproduce the above copyright
11	.\" notice, this list of conditions and the following disclaimer in the
12	.\" documentation and/or other materials provided with the distribution.
13	.\" 3. The name of the author may not be used to endorse or promote products
14	.\" derived from this software without specific prior written permission.
15	.\"
16	.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26	.\" SUCH DAMAGE.
27	.\"
28	.\"
29	.\" This is a minimal man page for GXemul. Process this file with
30	.\" groff -man -Tascii gxemul.1 or nroff -man gxemul.1
31	.\"
32	.Dd NOVEMBER 2005
33	.Dt GXEMUL 1
34	.Os
35	.Sh NAME
36	.Nm gxemul
37	.Nd an experimental machine emulator
38	.Sh SYNOPSIS
39	.Nm
40	.Op machine, other, and general options
41	.Op file Ar ...
42	.Nm
43	.Op general options
44	.Ar @configfile
45	.Nm
46	.Op userland, other, and general options
47	.Ar file Op Ar args ...
48	.Sh DESCRIPTION
49	.Nm
50	is an experimental instruction-level machine emulator. Several
51	emulation modes are available. In some modes, processors and surrounding
52	hardware components are emulated well enough to let unmodified operating
53	systems (e.g. NetBSD) run inside the emulator as if they were running on a
54	real machine.
55	.Pp
56	The processor architecture best emulated by GXemul is MIPS, but other
57	architectures (ARM and PowerPC) are also partially emulated.
58	.Pp
59	MIPS processors are emulated either using a simple type of binary
60	translator (on Alpha and i386 hosts), or using traditional slow
61	interpretation (all other hosts, including amd64 machines running in
62	64-bit mode).
63	.Pp
64	Non-MIPS processors are emulated using a newer dynamic
65	translation system (called dyntrans in the rest of this man page);
66	dyntrans does not require any host-specific code, so it should work on any
67	platform. Performance is somewhere between binary translation and
68	traditional interpretation.
69	.Pp
70	There are three ways to invoke the emulator:
71	.Pp
72	1. When emulating a complete machine, configuration options can be entered
73	directly on the command line.
74	.Pp
75	2. Options can be read from a configuration file.
76	.Pp
77	3. When emulating a userland environment (syscall-only emulation, not
78	emulating complete machines), then the program name and its argument
79	should be given on the command line. (This mode doesn't really work yet.)
80	.Pp
81	The easiest way to use the emulator is to supply settings directly on the
82	command line. The most important thing you need to supply is the
83	file argument. This is the name of a binary file (an ELF, a.out, COFF/ECOFF,
84	SREC, or a raw binary image) which you wish to run in the emulator. This file
85	might be an operating system kernel, or perhaps a ROM image file.
86	.Pp
87	If more than one filename is supplied, all files are loaded into memory,
88	and the entry point (if available) is taken from the last file.
89	.Pp
90	Apart from the name of a binary file, it is also necessary to select
91	which specific emulation mode to use. For example, a MIPS-based machine
92	from DEC (a DECstation) is very different from a MIPS-based machine
93	from SGI. Use
94	.Nm
95	.Fl H
96	to get a list of available emulation modes.
97	.Pp
98	There are two exceptions to the normal invocation usage mentioned above.
99	The first is for DECstation emulation: if you have a bootable
100	DECstation harddisk or CDROM image, then just supplying the diskimage via
101	the
102	.Fl d
103	option is sufficient. (The filename of the kernel can then be
104	skipped, as the emulator runs the bootblocks from the diskimage directly and
105	doesn't need the kernel as a separate file.)
106	The second is if you supply an ISO9660 CDROM disk image. You may then use
107	the
108	.Fl j
109	option to indicate which file on the CDROM filesystem that should be
110	loaded into emulated memory.
111	.Pp
112	Machine selection options:
113	.Bl -tag -width Ds
114	.It Fl E Ar t
115	Try to emulate machine type
116	.Ar "t".
117	This option is not always needed, if the
118	.Fl e
119	option uniquely selects a machine.
120	(Use
121	.Fl H
122	to get a list of types.)
123	.It Fl e Ar st
124	Try to emulate machine subtype
125	.Ar "st".
126	Use this together with
127	.Fl E .
128	(This option is not always needed, if a machine type has no subtypes.)
129	.El
130	.Pp
131	Other options:
132	.Bl -tag -width Ds
133	.It Fl A
134	Disable load/store alignment checks in some cases. This might give a small
135	increase in performance, but the emulator will not run correctly if the
136	emulated code actually tries to do unaligned loads or stores. (This option
137	is only meaningful when emulating MIPS CPUs, when the host architecture is
138	Alpha or i386, and binary translation is enabled.)
139	.It Fl B
140	Disable dynamic binary translation. By default, bintrans
141	will be turned on if the host+target architecture combination is
142	supported. Currently, the only supported target architecture for bintrans
143	is MIPS, and the supported host architectures are Alpha and i386.
144	.It Fl C Ar x
145	Try to emulate a specific CPU type,
146	.Ar "x".
147	This overrides the default CPU type for the machine being emulated.
148	(Use
149	.Fl H
150	to get a list of available CPU types.)
151	.It Fl d Ar name
152	Add
153	.Ar name
154	as a disk image. By adding one or more modifier characters and then a
155	colon (":") as a prefix to
156	.Ar "name",
157	you can modify the way the disk image is treated. Available modifiers are:
158	.Bl -tag -width Ds
159	.It b
160	Specifies that this is a boot device.
161	.It c
162	CD-ROM.
163	.It d
164	DISK (this is the default).
165	.It f
166	FLOPPY.
167	.It gH;S;
168	Override the default geometry; use H heads and S sectors-per-track.
169	(The number of cylinders is calculated automatically.)
170	.It i
171	IDE.
172	.It r
173	Read-only (don't allow changes to be written to the file).
174	.It s
175	SCSI (this is the default for most machine types).
176	.It t
177	Tape.
178	.It 0-7
179	Force a specific ID number.
180	.El
181	.Pp
182	Unless otherwise specified, filenames ending with ".iso" or ".cdr" are
183	assumed to be CDROM images. Most others are assumed to be disks. Depending
184	on which machine is being emulated, the default for disks can be either
185	SCSI or IDE. Some disk images that are very small are assumed to be floppy
186	disks. (If you are not happy with the way a disk image is detected, then
187	you need to use explicit prefixes to force a specific type.)
188	.Pp
189	For floppies, the gH;S; prefix is ignored. Instead, the number of
190	heads and cylinders are assumed to be 2 and 80, respectively, and the
191	number of sectors per track is calculated automatically. (This works for
192	720KB, 1.2MB, 1.44MB, and 2.88MB floppies.)
193	.It Fl I Ar x
194	Emulate clock interrupts at
195	.Ar x
196	Hz. (This affects emulated clock devices only, not actual runtime speed.
197	This disables automatic clock adjustments, which is otherwise turned on.)
198	(This option is probably only valid for DECstation emulation.)
199	.It Fl i
200	Display each instruction as it is being executed.
201	.It Fl J
202	Disable some speed tricks. For MIPS emulation, these are mostly
203	timing-related. For non-MIPS emulation (i.e. those modes using dyntrans),
204	this flag disables the use of "instruction combinations".
205	.It Fl j Ar n
206	Set the name of the kernel to
207	.Ar "n".
208	When booting from an ISO9660 filesystem, the emulator will try to boot
209	using this file. (In some emulation modes, eg. DECstation, this name is passed
210	along to the boot program. Useful names are "bsd" for OpenBSD/pmax,
211	or "vmunix" for Ultrix.)
212	.It Fl M Ar m
213	Emulate
214	.Ar m
215	MBs of physical RAM. This overrides the default amount of RAM for the
216	selected machine type.
217	.It Fl m Ar nr
218	Run at most
219	.Ar nr
220	instructions (on any cpu).
221	.It Fl N
222	Display nr of instructions/second average, at regular intervals.
223	.It Fl n Ar nr
224	Set nr of CPUs (for SMP experiments).
225	.It Fl O
226	Force a "netboot" (tftp instead of disk), even when a disk image is
227	present (for DECstation, SGI, and ARC emulation).
228	.It Fl o Ar arg
229	Set the boot argument (mostly useful for DEC, ARC, or SGI emulation).
230	Default
231	.Ar arg
232	for DEC is "-a", for ARC/SGI it is "-aN", and for CATS it is "-A".
233	.It Fl p Ar pc
234	Add a breakpoint. (Remember to use the "0x" prefix for hex.)
235	.It Fl Q
236	Disable the built-in PROM emulation. This is useful for running raw ROM
237	images from real machines.
238	.It Fl R
239	Use a random bootstrap cpu, instead of CPU nr 0. (For SMP experiments.)
240	.It Fl r
241	Dump register contents for every executed instruction.
242	.It Fl S
243	Initialize the emulated RAM to random data, instead of zeroes.
244	.It Fl T
245	Enter the single-step debugger on unimplemented memory accesses.
246	.It Fl t
247	Show a trace tree of all function calls being made.
248	.It Fl U
249	Enable slow_serial_interrupts_hack_for_linux.
250	.It Fl X
251	Use X11.
252	.It Fl x
253	Open up new xterms for emulated serial ports. (Default is to open up
254	xterms when using configuration files, but not when starting an
255	emulation with settings directly on the command line.)
256	.It Fl Y Ar n
257	Scale down framebuffer windows by
258	.Ar n
259	x
260	.Ar n
261	times. This option is useful when emulating a very large framebuffer, and
262	the actual display is of lower resolution. If
263	.Ar n
264	is negative, then there will be no scaledown, but emulation of certain
265	graphic controllers will be scaled up
266	by
267	.Ar -n
268	times instead. E.g. Using
269	.Ar -2
270	with VGA text mode emulation will result in 80x25 character cells rendered
271	in a 1280x800 window, instead of the normal resolution of 640x400.
272	.It Fl y Ar x
273	Set max_random_cycles_per_chunk to
274	.Ar x
275	(experimental).
276	.It Fl Z Ar n
277	Set the number of graphics cards, for emulating a dual-head or tripple-head
278	environment. (Only for DECstation emulation so far.)
279	.It Fl z Ar disp
280	Add
281	.Ar disp
282	as an X11 display to use for framebuffers.
283	.El
284	.Pp
285	Userland options:
286	.Bl -tag -width Ds
287	.It Fl u Ar emul-mode
288	Userland-only (syscall) emulation. (Use
289	.Fl H
290	to get a list of available emulation modes.) Some (but not all) of the
291	options listed under Other options above can also be used with userland
292	emulation.
293	.El
294	.Pp
295	General options:
296	.Bl -tag -width Ds
297	.It Fl D
298	Guarantee fully deterministic behavior. Normally, the emulator calls
299	srandom() with a seed based on the current time at startup. When the
300	.Fl D
301	option is used, the srandom() call is skipped, which should cause two
302	subsequent invocations of the emulator to be identical, if all other
303	settings are identical and no user input is taking place. (If this option
304	is used, then
305	.Fl I
306	must also be used.)
307	.It Fl H
308	Display a list of available CPU types, machine types, and userland
309	emulation modes. (Most of these don't work. Please read the documentation
310	included in the
311	.Nm
312	distribution for details on which modes that actually work.)
313	.It Fl h
314	Display a list of all available command line options.
315	.It Fl K
316	Force the single-step debugger to be entered at the end of a simulation.
317	.It Fl q
318	Quiet mode; this suppresses startup messages.
319	.It Fl s
320	For MIPS emulation: Show opcode usage statistics after the simulation.
321	For non-MIPS emulation (i.e. using dyntrans): Save statistics to a file at
322	regular intervals of which physical addresses that were executed.
323	.It Fl V
324	Start up in the single-step debugger, paused.
325	.It Fl v
326	Verbose debug messages.
327	.El
328	.Pp
329	Configuration file startup:
330	.Bl -tag -width Ds
331	.It @ Ar configfile
332	Start an emulation based on the contents of
333	.Ar "configfile".
334	.El
335	.Pp
336	For more information, please read the documentation in the doc/
337	subdirectory of the
338	.Nm
339	distribution.
340	.Sh EXAMPLES
341	The following command will start NetBSD/pmax on an emulated DECstation
342	5000/200 (3MAX):
343	.Pp
344	.Dl "gxemul -e 3max -d nbsd_pmax.img"
345	.Pp
346	nbsd_pmax.img should be a raw disk image containing a bootable
347	NetBSD/pmax filesystem.
348	.Pp
349	The following command will start an emulation session based on settings in
350	the configuration file "mysession". The -v option tells gxemul to be
351	verbose.
352	.Pp
353	.Dl "gxemul -v @mysession"
354	.Pp
355	If you have compiled the small Hello World program mentioned in the
356	.Nm
357	documentation, the following command will start up an
358	emulated test machine in "paused" mode:
359	.Pp
360	.Dl "gxemul -E testmips -V hello_mips"
361	.Pp
362	(Paused mode means that you enter the interactive single-step debugger
363	directly at startup, instead of launching the Hello World program.)
364	.Pp
365	Please read the documentation for more details.
366	.Sh BUGS
367	There are many bugs. Some of the known bugs are listed in the BUGS
368	file in the
369	.Nm
370	source distribution, some are indirectly mentioned in the TODO file,
371	and some are mentioned in the source code itself.
372	.Pp
373	The binary translation subsystem is really terrible, but it is less
374	terrible than running without it.
375	.Pp
376	Userland (syscall-only) emulation doesn't really work yet.
377	.Pp
378	Emulation of MIPS CPUs is done differently from other emulation modes; the
379	documentation sometimes only reflects the way things work with MIPS
380	emulation, and it is incorrect when applied to e.g. ARM emulation.
381	.Pp
382	.Nm
383	does not simulate individual pipe-line stages or penalties caused by
384	branch-prediction misses or cache misses, so it cannot be used for
385	accurate simulation of any actual real-world processor.
386	.Pp
387	.Nm
388	is not timing-accurate.
389	.Sh AUTHOR
390	Anders Gavare <anders@gavare.se>
391	.Pp
392	See http://gavare.se/gxemul/ for more information.