xref: /openbmc/qemu/docs/user/main.rst (revision bad5cfcd)
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
101``-singlestep``
102   This is a deprecated synonym for the ``-one-insn-per-tb`` option.
103
104Environment variables:
105
106QEMU_STRACE
107   Print system calls and arguments similar to the 'strace' program
108   (NOTE: the actual 'strace' program will not work because the user
109   space emulator hasn't implemented ptrace). At the moment this is
110   incomplete. All system calls that don't have a specific argument
111   format are printed with information for six arguments. Many
112   flag-style arguments don't have decoders and will show up as numbers.
113
114Other binaries
115~~~~~~~~~~~~~~
116
117-  user mode (Alpha)
118
119   * ``qemu-alpha`` TODO.
120
121-  user mode (Arm)
122
123   * ``qemu-armeb`` TODO.
124
125   * ``qemu-arm`` is also capable of running Arm \"Angel\" semihosted ELF
126     binaries (as implemented by the arm-elf and arm-eabi Newlib/GDB
127     configurations), and arm-uclinux bFLT format binaries.
128
129-  user mode (ColdFire)
130
131-  user mode (M68K)
132
133   * ``qemu-m68k`` is capable of running semihosted binaries using the BDM
134     (m5xxx-ram-hosted.ld) or m68k-sim (sim.ld) syscall interfaces, and
135     coldfire uClinux bFLT format binaries.
136
137   The binary format is detected automatically.
138
139-  user mode (Cris)
140
141   * ``qemu-cris`` TODO.
142
143-  user mode (i386)
144
145   * ``qemu-i386`` TODO.
146   * ``qemu-x86_64`` TODO.
147
148-  user mode (Microblaze)
149
150   * ``qemu-microblaze`` TODO.
151
152-  user mode (MIPS)
153
154   * ``qemu-mips`` executes 32-bit big endian MIPS binaries (MIPS O32 ABI).
155
156   * ``qemu-mipsel`` executes 32-bit little endian MIPS binaries (MIPS O32 ABI).
157
158   * ``qemu-mips64`` executes 64-bit big endian MIPS binaries (MIPS N64 ABI).
159
160   * ``qemu-mips64el`` executes 64-bit little endian MIPS binaries (MIPS N64
161     ABI).
162
163   * ``qemu-mipsn32`` executes 32-bit big endian MIPS binaries (MIPS N32 ABI).
164
165   * ``qemu-mipsn32el`` executes 32-bit little endian MIPS binaries (MIPS N32
166     ABI).
167
168-  user mode (NiosII)
169
170   * ``qemu-nios2`` TODO.
171
172-  user mode (PowerPC)
173
174   * ``qemu-ppc64`` TODO.
175   * ``qemu-ppc`` TODO.
176
177-  user mode (SH4)
178
179   * ``qemu-sh4eb`` TODO.
180   * ``qemu-sh4`` TODO.
181
182-  user mode (SPARC)
183
184   * ``qemu-sparc`` can execute Sparc32 binaries (Sparc32 CPU, 32 bit ABI).
185
186   * ``qemu-sparc32plus`` can execute Sparc32 and SPARC32PLUS binaries
187     (Sparc64 CPU, 32 bit ABI).
188
189   * ``qemu-sparc64`` can execute some Sparc64 (Sparc64 CPU, 64 bit ABI) and
190     SPARC32PLUS binaries (Sparc64 CPU, 32 bit ABI).
191
192BSD User space emulator
193-----------------------
194
195BSD Status
196~~~~~~~~~~
197
198-  target Sparc64 on Sparc64: Some trivial programs work.
199
200Quick Start
201~~~~~~~~~~~
202
203In order to launch a BSD process, QEMU needs the process executable
204itself and all the target dynamic libraries used by it.
205
206-  On Sparc64, you can just try to launch any process by using the
207   native libraries::
208
209      qemu-sparc64 /bin/ls
210
211Command line options
212~~~~~~~~~~~~~~~~~~~~
213
214::
215
216   qemu-sparc64 [-h] [-d] [-L path] [-s size] [-bsd type] program [arguments...]
217
218``-h``
219   Print the help
220
221``-L path``
222   Set the library root path (default=/)
223
224``-s size``
225   Set the stack size in bytes (default=524288)
226
227``-ignore-environment``
228   Start with an empty environment. Without this option, the initial
229   environment is a copy of the caller's environment.
230
231``-E var=value``
232   Set environment var to value.
233
234``-U var``
235   Remove var from the environment.
236
237``-bsd type``
238   Set the type of the emulated BSD Operating system. Valid values are
239   FreeBSD, NetBSD and OpenBSD (default).
240
241Debug options:
242
243``-d item1,...``
244   Activate logging of the specified items (use '-d help' for a list of
245   log items)
246
247``-p pagesize``
248   Act as if the host page size was 'pagesize' bytes
249
250``-one-insn-per-tb``
251   Run the emulation with one guest instruction per translation block.
252   This slows down emulation a lot, but can be useful in some situations,
253   such as when trying to analyse the logs produced by the ``-d`` option.
254
255``-singlestep``
256   This is a deprecated synonym for the ``-one-insn-per-tb`` option.
257