xref: /openbmc/qemu/docs/user/main.rst (revision daff9f7f)
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``-g port``
91   Wait gdb connection to port
92
93``-one-insn-per-tb``
94   Run the emulation with one guest instruction per translation block.
95   This slows down emulation a lot, but can be useful in some situations,
96   such as when trying to analyse the logs produced by the ``-d`` option.
97
98Environment variables:
99
100QEMU_STRACE
101   Print system calls and arguments similar to the 'strace' program
102   (NOTE: the actual 'strace' program will not work because the user
103   space emulator hasn't implemented ptrace). At the moment this is
104   incomplete. All system calls that don't have a specific argument
105   format are printed with information for six arguments. Many
106   flag-style arguments don't have decoders and will show up as numbers.
107
108Other binaries
109~~~~~~~~~~~~~~
110
111-  user mode (Alpha)
112
113   * ``qemu-alpha`` TODO.
114
115-  user mode (Arm)
116
117   * ``qemu-armeb`` TODO.
118
119   * ``qemu-arm`` is also capable of running Arm \"Angel\" semihosted ELF
120     binaries (as implemented by the arm-elf and arm-eabi Newlib/GDB
121     configurations), and arm-uclinux bFLT format binaries.
122
123-  user mode (ColdFire)
124
125-  user mode (M68K)
126
127   * ``qemu-m68k`` is capable of running semihosted binaries using the BDM
128     (m5xxx-ram-hosted.ld) or m68k-sim (sim.ld) syscall interfaces, and
129     coldfire uClinux bFLT format binaries.
130
131   The binary format is detected automatically.
132
133-  user mode (Cris)
134
135   * ``qemu-cris`` TODO.
136
137-  user mode (i386)
138
139   * ``qemu-i386`` TODO.
140   * ``qemu-x86_64`` TODO.
141
142-  user mode (Microblaze)
143
144   * ``qemu-microblaze`` TODO.
145
146-  user mode (MIPS)
147
148   * ``qemu-mips`` executes 32-bit big endian MIPS binaries (MIPS O32 ABI).
149
150   * ``qemu-mipsel`` executes 32-bit little endian MIPS binaries (MIPS O32 ABI).
151
152   * ``qemu-mips64`` executes 64-bit big endian MIPS binaries (MIPS N64 ABI).
153
154   * ``qemu-mips64el`` executes 64-bit little endian MIPS binaries (MIPS N64
155     ABI).
156
157   * ``qemu-mipsn32`` executes 32-bit big endian MIPS binaries (MIPS N32 ABI).
158
159   * ``qemu-mipsn32el`` executes 32-bit little endian MIPS binaries (MIPS N32
160     ABI).
161
162-  user mode (PowerPC)
163
164   * ``qemu-ppc64`` TODO.
165   * ``qemu-ppc`` TODO.
166
167-  user mode (SH4)
168
169   * ``qemu-sh4eb`` TODO.
170   * ``qemu-sh4`` TODO.
171
172-  user mode (SPARC)
173
174   * ``qemu-sparc`` can execute Sparc32 binaries (Sparc32 CPU, 32 bit ABI).
175
176   * ``qemu-sparc32plus`` can execute Sparc32 and SPARC32PLUS binaries
177     (Sparc64 CPU, 32 bit ABI).
178
179   * ``qemu-sparc64`` can execute some Sparc64 (Sparc64 CPU, 64 bit ABI) and
180     SPARC32PLUS binaries (Sparc64 CPU, 32 bit ABI).
181
182BSD User space emulator
183-----------------------
184
185BSD Status
186~~~~~~~~~~
187
188-  target Sparc64 on Sparc64: Some trivial programs work.
189
190Quick Start
191~~~~~~~~~~~
192
193In order to launch a BSD process, QEMU needs the process executable
194itself and all the target dynamic libraries used by it.
195
196-  On Sparc64, you can just try to launch any process by using the
197   native libraries::
198
199      qemu-sparc64 /bin/ls
200
201Command line options
202~~~~~~~~~~~~~~~~~~~~
203
204::
205
206   qemu-sparc64 [-h] [-d] [-L path] [-s size] [-bsd type] program [arguments...]
207
208``-h``
209   Print the help
210
211``-L path``
212   Set the library root path (default=/)
213
214``-s size``
215   Set the stack size in bytes (default=524288)
216
217``-ignore-environment``
218   Start with an empty environment. Without this option, the initial
219   environment is a copy of the caller's environment.
220
221``-E var=value``
222   Set environment var to value.
223
224``-U var``
225   Remove var from the environment.
226
227``-bsd type``
228   Set the type of the emulated BSD Operating system. Valid values are
229   FreeBSD, NetBSD and OpenBSD (default).
230
231Debug options:
232
233``-d item1,...``
234   Activate logging of the specified items (use '-d help' for a list of
235   log items)
236
237``-p pagesize``
238   Act as if the host page size was 'pagesize' bytes
239
240``-one-insn-per-tb``
241   Run the emulation with one guest instruction per translation block.
242   This slows down emulation a lot, but can be useful in some situations,
243   such as when trying to analyse the logs produced by the ``-d`` option.
244