xref: /openbmc/qemu/docs/user/main.rst (revision f279852b)
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``-singlestep``
97   Run the emulation in single step mode.
98
99Environment variables:
100
101QEMU_STRACE
102   Print system calls and arguments similar to the 'strace' program
103   (NOTE: the actual 'strace' program will not work because the user
104   space emulator hasn't implemented ptrace). At the moment this is
105   incomplete. All system calls that don't have a specific argument
106   format are printed with information for six arguments. Many
107   flag-style arguments don't have decoders and will show up as numbers.
108
109Other binaries
110~~~~~~~~~~~~~~
111
112-  user mode (Alpha)
113
114   * ``qemu-alpha`` TODO.
115
116-  user mode (Arm)
117
118   * ``qemu-armeb`` TODO.
119
120   * ``qemu-arm`` is also capable of running Arm \"Angel\" semihosted ELF
121     binaries (as implemented by the arm-elf and arm-eabi Newlib/GDB
122     configurations), and arm-uclinux bFLT format binaries.
123
124-  user mode (ColdFire)
125
126-  user mode (M68K)
127
128   * ``qemu-m68k`` is capable of running semihosted binaries using the BDM
129     (m5xxx-ram-hosted.ld) or m68k-sim (sim.ld) syscall interfaces, and
130     coldfire uClinux bFLT format binaries.
131
132   The binary format is detected automatically.
133
134-  user mode (Cris)
135
136   * ``qemu-cris`` TODO.
137
138-  user mode (i386)
139
140   * ``qemu-i386`` TODO.
141   * ``qemu-x86_64`` TODO.
142
143-  user mode (Microblaze)
144
145   * ``qemu-microblaze`` TODO.
146
147-  user mode (MIPS)
148
149   * ``qemu-mips`` executes 32-bit big endian MIPS binaries (MIPS O32 ABI).
150
151   * ``qemu-mipsel`` executes 32-bit little endian MIPS binaries (MIPS O32 ABI).
152
153   * ``qemu-mips64`` executes 64-bit big endian MIPS binaries (MIPS N64 ABI).
154
155   * ``qemu-mips64el`` executes 64-bit little endian MIPS binaries (MIPS N64
156     ABI).
157
158   * ``qemu-mipsn32`` executes 32-bit big endian MIPS binaries (MIPS N32 ABI).
159
160   * ``qemu-mipsn32el`` executes 32-bit little endian MIPS binaries (MIPS N32
161     ABI).
162
163-  user mode (NiosII)
164
165   * ``qemu-nios2`` TODO.
166
167-  user mode (PowerPC)
168
169   * ``qemu-ppc64`` TODO.
170   * ``qemu-ppc`` TODO.
171
172-  user mode (SH4)
173
174   * ``qemu-sh4eb`` TODO.
175   * ``qemu-sh4`` TODO.
176
177-  user mode (SPARC)
178
179   * ``qemu-sparc`` can execute Sparc32 binaries (Sparc32 CPU, 32 bit ABI).
180
181   * ``qemu-sparc32plus`` can execute Sparc32 and SPARC32PLUS binaries
182     (Sparc64 CPU, 32 bit ABI).
183
184   * ``qemu-sparc64`` can execute some Sparc64 (Sparc64 CPU, 64 bit ABI) and
185     SPARC32PLUS binaries (Sparc64 CPU, 32 bit ABI).
186
187BSD User space emulator
188-----------------------
189
190BSD Status
191~~~~~~~~~~
192
193-  target Sparc64 on Sparc64: Some trivial programs work.
194
195Quick Start
196~~~~~~~~~~~
197
198In order to launch a BSD process, QEMU needs the process executable
199itself and all the target dynamic libraries used by it.
200
201-  On Sparc64, you can just try to launch any process by using the
202   native libraries::
203
204      qemu-sparc64 /bin/ls
205
206Command line options
207~~~~~~~~~~~~~~~~~~~~
208
209::
210
211   qemu-sparc64 [-h] [-d] [-L path] [-s size] [-bsd type] program [arguments...]
212
213``-h``
214   Print the help
215
216``-L path``
217   Set the library root path (default=/)
218
219``-s size``
220   Set the stack size in bytes (default=524288)
221
222``-ignore-environment``
223   Start with an empty environment. Without this option, the initial
224   environment is a copy of the caller's environment.
225
226``-E var=value``
227   Set environment var to value.
228
229``-U var``
230   Remove var from the environment.
231
232``-bsd type``
233   Set the type of the emulated BSD Operating system. Valid values are
234   FreeBSD, NetBSD and OpenBSD (default).
235
236Debug options:
237
238``-d item1,...``
239   Activate logging of the specified items (use '-d help' for a list of
240   log items)
241
242``-p pagesize``
243   Act as if the host page size was 'pagesize' bytes
244
245``-singlestep``
246   Run the emulation in single step mode.
247