0.3.5/man/gxemul.1

.\" $Id: gxemul.1,v 1.29 2005/08/10 15:51:09 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 AUGUST 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
.Op Ar @configfile ...
.Nm
.Op userland, other, and general options
.Ar file Op Ar args ...
.Sh DESCRIPTION
.Nm
is an experimental instruction-level machine emulator. It can be used to
run binary code for MIPS-based machines, regardless of host
platform. Several emulation modes are available. For 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.
.Pp
(Non-MIPS emulation modes are also under development, but so far none of 
those modes has reached the completeness required to run unmodified
operating systems.) 
.Pp
There are three ways to invoke the emulator. When emulating a 
complete machine, settings can be entered directly on the command line, or
they can be read from a configuration file. 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.
.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, 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.
.It Fl B
Disable dynamic binary translation. By default, bintrans
will be turned on if the host+target architecture combination is 
supported.
.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" 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.
.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 (for DEC, ARC, or SGI emulation).
Default
.Ar arg
for DEC is "-a", for ARC "-aN".
.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.
.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
Show opcode usage statistics after the simulation.
.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
.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 performance measurement.
.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 1.29 2005/08/10 15:51:09 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 AUGUST 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	.Op 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. It can be used to
51	run binary code for MIPS-based machines, regardless of host
52	platform. Several emulation modes are available. For some modes,
53	processors and surrounding hardware components are emulated well enough to
54	let unmodified operating systems (e.g. NetBSD) run as if they were running
55	on a real machine.
56	.Pp
57	(Non-MIPS emulation modes are also under development, but so far none of
58	those modes has reached the completeness required to run unmodified
59	operating systems.)
60	.Pp
61	There are three ways to invoke the emulator. When emulating a
62	complete machine, settings can be entered directly on the command line, or
63	they can be read from a configuration file. When emulating a userland
64	environment (syscall-only emulation, not emulating complete machines),
65	then the program name and its argument should be given on the command
66	line.
67	.Pp
68	The easiest way to use the emulator is to supply settings directly on the
69	command line. The most important thing you need to supply is the
70	file argument. This is the name of a binary file (an ELF, a.out, ECOFF,
71	SREC, or a raw binary image) which you wish to run in the emulator. This file
72	might be an operating system kernel, or perhaps a ROM image file.
73	.Pp
74	If more than one filename is supplied, all files are loaded into memory,
75	and the entry point (if available) is taken from the last file.
76	.Pp
77	Apart from the name of a binary file, it is also necessary to select
78	which specific emulation mode to use. For example, a MIPS-based machine
79	from DEC (a DECstation) is very different from a MIPS-based machine
80	from SGI. Use
81	.Nm
82	.Fl H
83	to get a list of available emulation modes.
84	.Pp
85	There are two exceptions to the normal invocation usage mentioned above.
86	The first is for DECstation emulation: if you have a bootable
87	DECstation harddisk or CDROM image, then just supplying the diskimage via
88	the
89	.Fl d
90	option is sufficient. (The filename of the kernel can then be
91	skipped, as the emulator runs the bootblocks from the diskimage directly and
92	doesn't need the kernel as a separate file.)
93	The second is if you supply an ISO9660 CDROM disk image. You may then use
94	the
95	.Fl j
96	option to indicate which file on the CDROM filesystem that should be
97	loaded into emulated memory.
98	.Pp
99	Machine selection options:
100	.Bl -tag -width Ds
101	.It Fl E Ar t
102	Try to emulate machine type
103	.Ar "t".
104	This option is not always needed, if the
105	.Fl e
106	option uniquely selects a machine.
107	(Use
108	.Fl H
109	to get a list of types.)
110	.It Fl e Ar st
111	Try to emulate machine subtype
112	.Ar "st".
113	Use this together with
114	.Fl E .
115	(This option is not always needed, if a machine type has no subtypes.)
116	.El
117	.Pp
118	Other options:
119	.Bl -tag -width Ds
120	.It Fl A
121	Disable load/store alignment checks in some cases. This might give a small
122	increase in performance, but the emulator will not run correctly if the
123	emulated code actually tries to do unaligned loads or stores.
124	.It Fl B
125	Disable dynamic binary translation. By default, bintrans
126	will be turned on if the host+target architecture combination is
127	supported.
128	.It Fl C Ar x
129	Try to emulate a specific CPU type,
130	.Ar "x".
131	This overrides the default CPU type for the machine being emulated.
132	(Use
133	.Fl H
134	to get a list of available CPU types.)
135	.It Fl d Ar name
136	Add
137	.Ar name
138	as a disk image. By adding one or more modifier characters and then a
139	colon (":") as a prefix to
140	.Ar "name",
141	you can modify the way the disk image is treated. Available modifiers are:
142	.Bl -tag -width Ds
143	.It b
144	Specifies that this is a boot device.
145	.It c
146	CD-ROM.
147	.It d
148	DISK (this is the default).
149	.It f
150	FLOPPY.
151	.It gH;S;
152	Override the default geometry; use H heads and S sectors-per-track.
153	(The number of cylinders is calculated automatically.)
154	.It i
155	IDE.
156	.It r
157	Read-only (don't allow changes to be written to the file).
158	.It s
159	SCSI (this is the default for most machine types).
160	.It t
161	Tape.
162	.It 0-7
163	Force a specific ID number.
164	.El
165	.Pp
166	Unless otherwise specified, filenames ending with ".iso" are assumed to be
167	CDROM images. Most others are assumed to be disks. Depending on which
168	machine is being emulated, the default for disks can be either SCSI or
169	IDE. Some disk images that are very small are assumed to be floppy disks.
170	(If you are not happy with the way a disk image is detected, then you need
171	to use explicit prefixes to force a specific type.)
172	.Pp
173	For floppies, the gH;S; prefix is ignored. Instead, the number of
174	heads and cylinders are assumed to be 2 and 80, respectively, and the
175	number of sectors per track is calculated automatically. (This works for
176	720KB, 1.2MB, 1.44MB, and 2.88MB floppies.)
177	.It Fl I Ar x
178	Emulate clock interrupts at
179	.Ar x
180	Hz. (This affects emulated clock devices only, not actual runtime speed.
181	This disables automatic clock adjustments, which is otherwise turned on.)
182	(This option is probably only valid for DECstation emulation.)
183	.It Fl i
184	Display each instruction as it is being executed.
185	.It Fl J
186	Disable some speed tricks.
187	.It Fl j Ar n
188	Set the name of the kernel to
189	.Ar "n".
190	When booting from an ISO9660 filesystem, the emulator will try to boot
191	using this file. (In some emulation modes, eg. DECstation, this name is passed
192	along to the boot program. Useful names are "bsd" for OpenBSD/pmax,
193	or "vmunix" for Ultrix.)
194	.It Fl M Ar m
195	Emulate
196	.Ar m
197	MBs of physical RAM. This overrides the default amount of RAM for the
198	selected machine type.
199	.It Fl m Ar nr
200	Run at most
201	.Ar nr
202	instructions (on any cpu).
203	.It Fl N
204	Display nr of instructions/second average, at regular intervals.
205	.It Fl n Ar nr
206	Set nr of CPUs (for SMP experiments).
207	.It Fl O
208	Force a "netboot" (tftp instead of disk), even when a disk image is
209	present (for DECstation, SGI, and ARC emulation).
210	.It Fl o Ar arg
211	Set the boot argument (for DEC, ARC, or SGI emulation).
212	Default
213	.Ar arg
214	for DEC is "-a", for ARC "-aN".
215	.It Fl p Ar pc
216	Add a breakpoint. (Remember to use the "0x" prefix for hex.)
217	.It Fl Q
218	Disable the built-in PROM emulation. This is useful for running raw ROM
219	images from real machines.
220	.It Fl R
221	Use a random bootstrap cpu, instead of CPU nr 0. (For SMP experiments.)
222	.It Fl r
223	Dump register contents for every executed instruction.
224	.It Fl S
225	Initialize the emulated RAM to random data, instead of zeroes.
226	.It Fl T
227	Enter the single-step debugger on unimplemented memory accesses.
228	.It Fl t
229	Show a trace tree of all function calls being made.
230	.It Fl U
231	Enable slow_serial_interrupts_hack_for_linux.
232	.It Fl X
233	Use X11.
234	.It Fl x
235	Open up new xterms for emulated serial ports. (Default is to open up
236	xterms when using configuration files, but not when starting an
237	emulation with settings directly on the command line.)
238	.It Fl Y Ar n
239	Scale down framebuffer windows by
240	.Ar n
241	x
242	.Ar n
243	times.
244	.It Fl y Ar x
245	Set max_random_cycles_per_chunk to
246	.Ar x
247	(experimental).
248	.It Fl Z Ar n
249	Set the number of graphics cards, for emulating a dual-head or tripple-head
250	environment. (Only for DECstation emulation so far.)
251	.It Fl z Ar disp
252	Add
253	.Ar disp
254	as an X11 display to use for framebuffers.
255	.El
256	.Pp
257	Userland options:
258	.Bl -tag -width Ds
259	.It Fl u Ar emul-mode
260	Userland-only (syscall) emulation. (Use
261	.Fl H
262	to get a list of available emulation modes.) Some (but not all) of the
263	options listed under Other options above can also be used with userland
264	emulation.
265	.El
266	.Pp
267	General options:
268	.Bl -tag -width Ds
269	.It Fl D
270	Guarantee fully deterministic behavior. Normally, the emulator calls
271	srandom() with a seed based on the current time at startup. When the
272	.Fl D
273	option is used, the srandom() call is skipped, which should cause two
274	subsequent invocations of the emulator to be identical, if all other
275	settings are identical and no user input is taking place. (If this option
276	is used, then
277	.Fl I
278	must also be used.)
279	.It Fl H
280	Display a list of available CPU types, machine types, and userland
281	emulation modes. (Most of these don't work. Please read the documentation
282	included in the
283	.Nm
284	distribution for details on which modes that actually work.)
285	.It Fl h
286	Display a list of all available command line options.
287	.It Fl K
288	Force the single-step debugger to be entered at the end of a simulation.
289	.It Fl q
290	Quiet mode; this suppresses startup messages.
291	.It Fl s
292	Show opcode usage statistics after the simulation.
293	.It Fl V
294	Start up in the single-step debugger, paused.
295	.It Fl v
296	Verbose debug messages.
297	.El
298	.Pp
299	Configuration file startup:
300	.Bl -tag -width Ds
301	.It @ Ar configfile
302	Start an emulation based on the contents of
303	.Ar "configfile".
304	.El
305	.Pp
306	For more information, please read the documentation in the doc/
307	subdirectory of the
308	.Nm
309	distribution.
310	.Sh EXAMPLES
311	The following command will start NetBSD/pmax on an emulated DECstation
312	5000/200 (3MAX):
313	.Pp
314	.Dl "gxemul -e 3max -d nbsd_pmax.img"
315	.Pp
316	nbsd_pmax.img should be a raw disk image containing a bootable
317	NetBSD/pmax filesystem.
318	.Pp
319	The following command will start an emulation session based on settings in
320	the configuration file "mysession". The -v option tells gxemul to be
321	verbose.
322	.Pp
323	.Dl "gxemul -v @mysession"
324	.Pp
325	If you have compiled the small Hello World program mentioned in the
326	.Nm
327	documentation, the following command will start up an
328	emulated test machine in "paused" mode:
329	.Pp
330	.Dl "gxemul -E testmips -V hello_mips"
331	.Pp
332	(Paused mode means that you enter the interactive single-step debugger
333	directly at startup, instead of launching the Hello World program.)
334	.Pp
335	Please read the documentation for more details.
336	.Sh BUGS
337	There are many bugs. Some of the known bugs are listed in the BUGS
338	file in the
339	.Nm
340	source distribution, some are indirectly mentioned in the TODO file,
341	and some are mentioned in the source code itself.
342	.Pp
343	The binary translation subsystem is really terrible, but it is less
344	terrible than running without it.
345	.Pp
346	Userland (syscall-only) emulation doesn't really work yet.
347	.Pp
348	.Nm
349	does not simulate individual pipe-line stages or penalties caused by
350	branch-prediction misses or cache misses, so it cannot be used for
351	accurate performance measurement.
352	.Pp
353	.Nm
354	is not timing-accurate.
355	.Sh AUTHOR
356	Anders Gavare <anders@gavare.se>
357	.Pp
358	See http://gavare.se/gxemul/ for more information.