xref: /openbmc/qemu/docs/user/main.rst (revision effd60c8)
1QEMU User space emulator
2========================
3
4Supported Operating Systems
5---------------------------
6
7The following OS are supported in user space emulation:
8
9-  Linux (referred as qemu-linux-user)
10
11-  BSD (referred as qemu-bsd-user)
12
13Features
14--------
15
16QEMU user space emulation has the following notable features:
17
18**System call translation:**
19   QEMU includes a generic system call translator. This means that the
20   parameters of the system calls can be converted to fix endianness and
21   32/64-bit mismatches between hosts and targets. IOCTLs can be
22   converted too.
23
24**POSIX signal handling:**
25   QEMU can redirect to the running program all signals coming from the
26   host (such as ``SIGALRM``), as well as synthesize signals from
27   virtual CPU exceptions (for example ``SIGFPE`` when the program
28   executes a division by zero).
29
30   QEMU relies on the host kernel to emulate most signal system calls,
31   for example to emulate the signal mask. On Linux, QEMU supports both
32   normal and real-time signals.
33
34**Threading:**
35   On Linux, QEMU can emulate the ``clone`` syscall and create a real
36   host thread (with a separate virtual CPU) for each emulated thread.
37   Note that not all targets currently emulate atomic operations
38   correctly. x86 and Arm use a global lock in order to preserve their
39   semantics.
40
41QEMU was conceived so that ultimately it can emulate itself. Although it
42is not very useful, it is an important test to show the power of the
43emulator.
44
45Linux User space emulator
46-------------------------
47
48Command line options
49~~~~~~~~~~~~~~~~~~~~
50
51::
52
53   qemu-i386 [-h] [-d] [-L path] [-s size] [-cpu model] [-g port] [-B offset] [-R size] program [arguments...]
54
55``-h``
56   Print the help
57
58``-L path``
59   Set the x86 elf interpreter prefix (default=/usr/local/qemu-i386)
60
61``-s size``
62   Set the x86 stack size in bytes (default=524288)
63
64``-cpu model``
65   Select CPU model (-cpu help for list and additional feature
66   selection)
67
68``-E var=value``
69   Set environment var to value.
70
71``-U var``
72   Remove var from the environment.
73
74``-B offset``
75   Offset guest address by the specified number of bytes. This is useful
76   when the address region required by guest applications is reserved on
77   the host. This option is currently only supported on some hosts.
78
79``-R size``
80   Pre-allocate a guest virtual address space of the given size (in
81   bytes). \"G\", \"M\", and \"k\" suffixes may be used when specifying
82   the size.
83
84Debug options:
85
86``-d item1,...``
87   Activate logging of the specified items (use '-d help' for a list of
88   log items)
89
90``-p pagesize``
91   Act as if the host page size was 'pagesize' bytes
92
93``-g port``
94   Wait gdb connection to port
95
96``-one-insn-per-tb``
97   Run the emulation with one guest instruction per translation block.
98   This slows down emulation a lot, but can be useful in some situations,
99   such as when trying to analyse the logs produced by the ``-d`` option.
100
101Environment variables:
102
103QEMU_STRACE
104   Print system calls and arguments similar to the 'strace' program
105   (NOTE: the actual 'strace' program will not work because the user
106   space emulator hasn't implemented ptrace). At the moment this is
107   incomplete. All system calls that don't have a specific argument
108   format are printed with information for six arguments. Many
109   flag-style arguments don't have decoders and will show up as numbers.
110
111Other binaries
112~~~~~~~~~~~~~~
113
114-  user mode (Alpha)
115
116   * ``qemu-alpha`` TODO.
117
118-  user mode (Arm)
119
120   * ``qemu-armeb`` TODO.
121
122   * ``qemu-arm`` is also capable of running Arm \"Angel\" semihosted ELF
123     binaries (as implemented by the arm-elf and arm-eabi Newlib/GDB
124     configurations), and arm-uclinux bFLT format binaries.
125
126-  user mode (ColdFire)
127
128-  user mode (M68K)
129
130   * ``qemu-m68k`` is capable of running semihosted binaries using the BDM
131     (m5xxx-ram-hosted.ld) or m68k-sim (sim.ld) syscall interfaces, and
132     coldfire uClinux bFLT format binaries.
133
134   The binary format is detected automatically.
135
136-  user mode (Cris)
137
138   * ``qemu-cris`` TODO.
139
140-  user mode (i386)
141
142   * ``qemu-i386`` TODO.
143   * ``qemu-x86_64`` TODO.
144
145-  user mode (Microblaze)
146
147   * ``qemu-microblaze`` TODO.
148
149-  user mode (MIPS)
150
151   * ``qemu-mips`` executes 32-bit big endian MIPS binaries (MIPS O32 ABI).
152
153   * ``qemu-mipsel`` executes 32-bit little endian MIPS binaries (MIPS O32 ABI).
154
155   * ``qemu-mips64`` executes 64-bit big endian MIPS binaries (MIPS N64 ABI).
156
157   * ``qemu-mips64el`` executes 64-bit little endian MIPS binaries (MIPS N64
158     ABI).
159
160   * ``qemu-mipsn32`` executes 32-bit big endian MIPS binaries (MIPS N32 ABI).
161
162   * ``qemu-mipsn32el`` executes 32-bit little endian MIPS binaries (MIPS N32
163     ABI).
164
165-  user mode (NiosII)
166
167   * ``qemu-nios2`` TODO.
168
169-  user mode (PowerPC)
170
171   * ``qemu-ppc64`` TODO.
172   * ``qemu-ppc`` TODO.
173
174-  user mode (SH4)
175
176   * ``qemu-sh4eb`` TODO.
177   * ``qemu-sh4`` TODO.
178
179-  user mode (SPARC)
180
181   * ``qemu-sparc`` can execute Sparc32 binaries (Sparc32 CPU, 32 bit ABI).
182
183   * ``qemu-sparc32plus`` can execute Sparc32 and SPARC32PLUS binaries
184     (Sparc64 CPU, 32 bit ABI).
185
186   * ``qemu-sparc64`` can execute some Sparc64 (Sparc64 CPU, 64 bit ABI) and
187     SPARC32PLUS binaries (Sparc64 CPU, 32 bit ABI).
188
189BSD User space emulator
190-----------------------
191
192BSD Status
193~~~~~~~~~~
194
195-  target Sparc64 on Sparc64: Some trivial programs work.
196
197Quick Start
198~~~~~~~~~~~
199
200In order to launch a BSD process, QEMU needs the process executable
201itself and all the target dynamic libraries used by it.
202
203-  On Sparc64, you can just try to launch any process by using the
204   native libraries::
205
206      qemu-sparc64 /bin/ls
207
208Command line options
209~~~~~~~~~~~~~~~~~~~~
210
211::
212
213   qemu-sparc64 [-h] [-d] [-L path] [-s size] [-bsd type] program [arguments...]
214
215``-h``
216   Print the help
217
218``-L path``
219   Set the library root path (default=/)
220
221``-s size``
222   Set the stack size in bytes (default=524288)
223
224``-ignore-environment``
225   Start with an empty environment. Without this option, the initial
226   environment is a copy of the caller's environment.
227
228``-E var=value``
229   Set environment var to value.
230
231``-U var``
232   Remove var from the environment.
233
234``-bsd type``
235   Set the type of the emulated BSD Operating system. Valid values are
236   FreeBSD, NetBSD and OpenBSD (default).
237
238Debug options:
239
240``-d item1,...``
241   Activate logging of the specified items (use '-d help' for a list of
242   log items)
243
244``-p pagesize``
245   Act as if the host page size was 'pagesize' bytes
246
247``-one-insn-per-tb``
248   Run the emulation with one guest instruction per translation block.
249   This slows down emulation a lot, but can be useful in some situations,
250   such as when trying to analyse the logs produced by the ``-d`` option.
251