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1 | 386405f7 | bellard | \input texinfo @c -*- texinfo -*- |
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2 | 386405f7 | bellard | |
3 | 0806e3f6 | bellard | @iftex |
4 | 322d0c66 | bellard | @settitle QEMU CPU Emulator Reference Documentation |
5 | 386405f7 | bellard | @titlepage |
6 | 386405f7 | bellard | @sp 7 |
7 | 322d0c66 | bellard | @center @titlefont{QEMU CPU Emulator Reference Documentation} |
8 | 386405f7 | bellard | @sp 3 |
9 | 386405f7 | bellard | @end titlepage |
10 | 0806e3f6 | bellard | @end iftex |
11 | 386405f7 | bellard | |
12 | 386405f7 | bellard | @chapter Introduction |
13 | 386405f7 | bellard | |
14 | 322d0c66 | bellard | @section Features |
15 | 386405f7 | bellard | |
16 | 1eb20527 | bellard | QEMU is a FAST! processor emulator. By using dynamic translation it |
17 | 1eb20527 | bellard | achieves a reasonnable speed while being easy to port on new host |
18 | 1eb20527 | bellard | CPUs. |
19 | 1eb20527 | bellard | |
20 | 1eb20527 | bellard | QEMU has two operating modes: |
21 | 0806e3f6 | bellard | |
22 | 0806e3f6 | bellard | @itemize @minus |
23 | 0806e3f6 | bellard | |
24 | 0806e3f6 | bellard | @item |
25 | 0806e3f6 | bellard | User mode emulation. In this mode, QEMU can launch Linux processes |
26 | 1eb20527 | bellard | compiled for one CPU on another CPU. Linux system calls are converted |
27 | 1eb20527 | bellard | because of endianness and 32/64 bit mismatches. The Wine Windows API |
28 | 1eb20527 | bellard | emulator (@url{http://www.winehq.org}) and the DOSEMU DOS emulator |
29 | 2be3bc02 | bellard | (@url{http://www.dosemu.org}) are the main targets for QEMU. |
30 | 1eb20527 | bellard | |
31 | 0806e3f6 | bellard | @item |
32 | 0806e3f6 | bellard | Full system emulation. In this mode, QEMU emulates a full |
33 | 1eb20527 | bellard | system, including a processor and various peripherials. Currently, it |
34 | 1eb20527 | bellard | is only used to launch an x86 Linux kernel on an x86 Linux system. It |
35 | 1eb20527 | bellard | enables easier testing and debugging of system code. It can also be |
36 | 1eb20527 | bellard | used to provide virtual hosting of several virtual PCs on a single |
37 | 1eb20527 | bellard | server. |
38 | 1eb20527 | bellard | |
39 | 1eb20527 | bellard | @end itemize |
40 | 1eb20527 | bellard | |
41 | 1eb20527 | bellard | As QEMU requires no host kernel patches to run, it is very safe and |
42 | 1eb20527 | bellard | easy to use. |
43 | 322d0c66 | bellard | |
44 | 322d0c66 | bellard | QEMU generic features: |
45 | 386405f7 | bellard | |
46 | 386405f7 | bellard | @itemize |
47 | 386405f7 | bellard | |
48 | 1eb20527 | bellard | @item User space only or full system emulation. |
49 | 1eb20527 | bellard | |
50 | 1eb20527 | bellard | @item Using dynamic translation to native code for reasonnable speed. |
51 | 386405f7 | bellard | |
52 | 322d0c66 | bellard | @item Working on x86 and PowerPC hosts. Being tested on ARM, Sparc32, Alpha and S390. |
53 | 386405f7 | bellard | |
54 | 1eb20527 | bellard | @item Self-modifying code support. |
55 | 1eb20527 | bellard | |
56 | d5a0b50c | bellard | @item Precise exceptions support. |
57 | 386405f7 | bellard | |
58 | 1eb20527 | bellard | @item The virtual CPU is a library (@code{libqemu}) which can be used |
59 | 1eb20527 | bellard | in other projects. |
60 | 1eb20527 | bellard | |
61 | 1eb20527 | bellard | @end itemize |
62 | 1eb20527 | bellard | |
63 | 1eb20527 | bellard | QEMU user mode emulation features: |
64 | 1eb20527 | bellard | @itemize |
65 | 386405f7 | bellard | @item Generic Linux system call converter, including most ioctls. |
66 | 386405f7 | bellard | |
67 | 386405f7 | bellard | @item clone() emulation using native CPU clone() to use Linux scheduler for threads. |
68 | 386405f7 | bellard | |
69 | 322d0c66 | bellard | @item Accurate signal handling by remapping host signals to target signals. |
70 | 1eb20527 | bellard | @end itemize |
71 | 1eb20527 | bellard | @end itemize |
72 | df0f11a0 | bellard | |
73 | 1eb20527 | bellard | QEMU full system emulation features: |
74 | 1eb20527 | bellard | @itemize |
75 | 285dc330 | bellard | @item QEMU can either use a full software MMU for maximum portability or use the host system call mmap() to simulate the target MMU. |
76 | 322d0c66 | bellard | @end itemize |
77 | 322d0c66 | bellard | |
78 | 322d0c66 | bellard | @section x86 emulation |
79 | 322d0c66 | bellard | |
80 | 322d0c66 | bellard | QEMU x86 target features: |
81 | 322d0c66 | bellard | |
82 | 322d0c66 | bellard | @itemize |
83 | 322d0c66 | bellard | |
84 | 322d0c66 | bellard | @item The virtual x86 CPU supports 16 bit and 32 bit addressing with segmentation. |
85 | 1eb20527 | bellard | LDT/GDT and IDT are emulated. VM86 mode is also supported to run DOSEMU. |
86 | 322d0c66 | bellard | |
87 | 1eb20527 | bellard | @item Support of host page sizes bigger than 4KB in user mode emulation. |
88 | df0f11a0 | bellard | |
89 | df0f11a0 | bellard | @item QEMU can emulate itself on x86. |
90 | 1eb87257 | bellard | |
91 | 386405f7 | bellard | @item An extensive Linux x86 CPU test program is included @file{tests/test-i386}. |
92 | 386405f7 | bellard | It can be used to test other x86 virtual CPUs. |
93 | 386405f7 | bellard | |
94 | 386405f7 | bellard | @end itemize |
95 | 386405f7 | bellard | |
96 | df0f11a0 | bellard | Current QEMU limitations: |
97 | 386405f7 | bellard | |
98 | 386405f7 | bellard | @itemize |
99 | 386405f7 | bellard | |
100 | 386405f7 | bellard | @item No SSE/MMX support (yet). |
101 | 386405f7 | bellard | |
102 | 386405f7 | bellard | @item No x86-64 support. |
103 | 386405f7 | bellard | |
104 | df0f11a0 | bellard | @item IPC syscalls are missing. |
105 | 386405f7 | bellard | |
106 | 386405f7 | bellard | @item The x86 segment limits and access rights are not tested at every |
107 | 1eb20527 | bellard | memory access. |
108 | 386405f7 | bellard | |
109 | 386405f7 | bellard | @item On non x86 host CPUs, @code{double}s are used instead of the non standard |
110 | 386405f7 | bellard | 10 byte @code{long double}s of x86 for floating point emulation to get |
111 | 386405f7 | bellard | maximum performances. |
112 | 386405f7 | bellard | |
113 | 285dc330 | bellard | @item Some priviledged instructions or behaviors are missing, especially for segment protection testing (yet). |
114 | 1eb20527 | bellard | |
115 | 386405f7 | bellard | @end itemize |
116 | 386405f7 | bellard | |
117 | 322d0c66 | bellard | @section ARM emulation |
118 | 322d0c66 | bellard | |
119 | 322d0c66 | bellard | @itemize |
120 | 322d0c66 | bellard | |
121 | 322d0c66 | bellard | @item ARM emulation can currently launch small programs while using the |
122 | 322d0c66 | bellard | generic dynamic code generation architecture of QEMU. |
123 | 322d0c66 | bellard | |
124 | 322d0c66 | bellard | @item No FPU support (yet). |
125 | 322d0c66 | bellard | |
126 | 322d0c66 | bellard | @item No automatic regression testing (yet). |
127 | 322d0c66 | bellard | |
128 | 322d0c66 | bellard | @end itemize |
129 | 322d0c66 | bellard | |
130 | 0806e3f6 | bellard | @section SPARC emulation |
131 | 0806e3f6 | bellard | |
132 | 0806e3f6 | bellard | The SPARC emulation is currently in development. |
133 | 0806e3f6 | bellard | |
134 | 5b9f457a | bellard | @chapter Installation |
135 | 5b9f457a | bellard | |
136 | 5b9f457a | bellard | If you want to compile QEMU, please read the @file{README} which gives |
137 | 5b9f457a | bellard | the related information. Otherwise just download the binary |
138 | 5b9f457a | bellard | distribution (@file{qemu-XXX-i386.tar.gz}) and untar it as root in |
139 | 5b9f457a | bellard | @file{/}: |
140 | 5b9f457a | bellard | |
141 | 5b9f457a | bellard | @example |
142 | 5b9f457a | bellard | su |
143 | 5b9f457a | bellard | cd / |
144 | 5b9f457a | bellard | tar zxvf /tmp/qemu-XXX-i386.tar.gz |
145 | 5b9f457a | bellard | @end example |
146 | 5b9f457a | bellard | |
147 | d5a0b50c | bellard | @chapter QEMU User space emulator invocation |
148 | 386405f7 | bellard | |
149 | d691f669 | bellard | @section Quick Start |
150 | d691f669 | bellard | |
151 | 386405f7 | bellard | In order to launch a Linux process, QEMU needs the process executable |
152 | d691f669 | bellard | itself and all the target (x86) dynamic libraries used by it. |
153 | d691f669 | bellard | |
154 | d691f669 | bellard | @itemize |
155 | 386405f7 | bellard | |
156 | d691f669 | bellard | @item On x86, you can just try to launch any process by using the native |
157 | d691f669 | bellard | libraries: |
158 | 386405f7 | bellard | |
159 | 386405f7 | bellard | @example |
160 | 0806e3f6 | bellard | qemu-i386 -L / /bin/ls |
161 | 386405f7 | bellard | @end example |
162 | 386405f7 | bellard | |
163 | d691f669 | bellard | @code{-L /} tells that the x86 dynamic linker must be searched with a |
164 | d691f669 | bellard | @file{/} prefix. |
165 | 386405f7 | bellard | |
166 | 5b9f457a | bellard | @item Since QEMU is also a linux process, you can launch qemu with qemu (NOTE: you can only do that if you compiled QEMU from the sources): |
167 | 1eb87257 | bellard | |
168 | 1eb87257 | bellard | @example |
169 | 0806e3f6 | bellard | qemu-i386 -L / qemu-i386 -L / /bin/ls |
170 | 1eb87257 | bellard | @end example |
171 | 386405f7 | bellard | |
172 | d691f669 | bellard | @item On non x86 CPUs, you need first to download at least an x86 glibc |
173 | 5b9f457a | bellard | (@file{qemu-runtime-i386-XXX-.tar.gz} on the QEMU web page). Ensure that |
174 | 644c433c | bellard | @code{LD_LIBRARY_PATH} is not set: |
175 | 644c433c | bellard | |
176 | 644c433c | bellard | @example |
177 | 644c433c | bellard | unset LD_LIBRARY_PATH |
178 | 644c433c | bellard | @end example |
179 | 644c433c | bellard | |
180 | 644c433c | bellard | Then you can launch the precompiled @file{ls} x86 executable: |
181 | 644c433c | bellard | |
182 | d691f669 | bellard | @example |
183 | 285dc330 | bellard | qemu-i386 tests/i386/ls |
184 | 168485b7 | bellard | @end example |
185 | 285dc330 | bellard | You can look at @file{qemu-binfmt-conf.sh} so that |
186 | 168485b7 | bellard | QEMU is automatically launched by the Linux kernel when you try to |
187 | 168485b7 | bellard | launch x86 executables. It requires the @code{binfmt_misc} module in the |
188 | 168485b7 | bellard | Linux kernel. |
189 | 168485b7 | bellard | |
190 | 1eb87257 | bellard | @item The x86 version of QEMU is also included. You can try weird things such as: |
191 | 1eb87257 | bellard | @example |
192 | 0806e3f6 | bellard | qemu-i386 /usr/local/qemu-i386/bin/qemu-i386 /usr/local/qemu-i386/bin/ls-i386 |
193 | 1eb87257 | bellard | @end example |
194 | 1eb87257 | bellard | |
195 | 168485b7 | bellard | @end itemize |
196 | 168485b7 | bellard | |
197 | df0f11a0 | bellard | @section Wine launch |
198 | 168485b7 | bellard | |
199 | 168485b7 | bellard | @itemize |
200 | 168485b7 | bellard | |
201 | 168485b7 | bellard | @item Ensure that you have a working QEMU with the x86 glibc |
202 | 168485b7 | bellard | distribution (see previous section). In order to verify it, you must be |
203 | 168485b7 | bellard | able to do: |
204 | 168485b7 | bellard | |
205 | 168485b7 | bellard | @example |
206 | 0806e3f6 | bellard | qemu-i386 /usr/local/qemu-i386/bin/ls-i386 |
207 | 168485b7 | bellard | @end example |
208 | 168485b7 | bellard | |
209 | fd429f2f | bellard | @item Download the binary x86 Wine install |
210 | 1eb87257 | bellard | (@file{qemu-XXX-i386-wine.tar.gz} on the QEMU web page). |
211 | 168485b7 | bellard | |
212 | fd429f2f | bellard | @item Configure Wine on your account. Look at the provided script |
213 | 168485b7 | bellard | @file{/usr/local/qemu-i386/bin/wine-conf.sh}. Your previous |
214 | 168485b7 | bellard | @code{$@{HOME@}/.wine} directory is saved to @code{$@{HOME@}/.wine.org}. |
215 | 168485b7 | bellard | |
216 | 168485b7 | bellard | @item Then you can try the example @file{putty.exe}: |
217 | 168485b7 | bellard | |
218 | 168485b7 | bellard | @example |
219 | 0806e3f6 | bellard | qemu-i386 /usr/local/qemu-i386/wine/bin/wine /usr/local/qemu-i386/wine/c/Program\ Files/putty.exe |
220 | 386405f7 | bellard | @end example |
221 | d691f669 | bellard | |
222 | d691f669 | bellard | @end itemize |
223 | d691f669 | bellard | |
224 | d691f669 | bellard | @section Command line options |
225 | d691f669 | bellard | |
226 | d691f669 | bellard | @example |
227 | 0806e3f6 | bellard | usage: qemu-i386 [-h] [-d] [-L path] [-s size] program [arguments...] |
228 | d691f669 | bellard | @end example |
229 | d691f669 | bellard | |
230 | df0f11a0 | bellard | @table @option |
231 | d691f669 | bellard | @item -h |
232 | d691f669 | bellard | Print the help |
233 | d691f669 | bellard | @item -L path |
234 | d691f669 | bellard | Set the x86 elf interpreter prefix (default=/usr/local/qemu-i386) |
235 | d691f669 | bellard | @item -s size |
236 | d691f669 | bellard | Set the x86 stack size in bytes (default=524288) |
237 | d691f669 | bellard | @end table |
238 | 386405f7 | bellard | |
239 | df0f11a0 | bellard | Debug options: |
240 | df0f11a0 | bellard | |
241 | df0f11a0 | bellard | @table @option |
242 | df0f11a0 | bellard | @item -d |
243 | df0f11a0 | bellard | Activate log (logfile=/tmp/qemu.log) |
244 | df0f11a0 | bellard | @item -p pagesize |
245 | df0f11a0 | bellard | Act as if the host page size was 'pagesize' bytes |
246 | df0f11a0 | bellard | @end table |
247 | df0f11a0 | bellard | |
248 | 1eb20527 | bellard | @chapter QEMU System emulator invocation |
249 | 1eb20527 | bellard | |
250 | 0806e3f6 | bellard | @section Introduction |
251 | 0806e3f6 | bellard | |
252 | 0806e3f6 | bellard | @c man begin DESCRIPTION |
253 | 0806e3f6 | bellard | |
254 | 0806e3f6 | bellard | The QEMU System emulator simulates a complete PC. It can either boot |
255 | 0806e3f6 | bellard | directly a Linux kernel (without any BIOS or boot loader) or boot like a |
256 | 0806e3f6 | bellard | real PC with the included BIOS. |
257 | 0806e3f6 | bellard | |
258 | 0806e3f6 | bellard | In order to meet specific user needs, two versions of QEMU are |
259 | 0806e3f6 | bellard | available: |
260 | 0806e3f6 | bellard | |
261 | 0806e3f6 | bellard | @enumerate |
262 | 0806e3f6 | bellard | |
263 | 0806e3f6 | bellard | @item |
264 | 285dc330 | bellard | @code{qemu-fast} uses the host Memory Management Unit (MMU) to simulate |
265 | 0806e3f6 | bellard | the x86 MMU. It is @emph{fast} but has limitations because the whole 4 GB |
266 | 0806e3f6 | bellard | address space cannot be used and some memory mapped peripherials |
267 | 0806e3f6 | bellard | cannot be emulated accurately yet. Therefore, a specific Linux kernel |
268 | 0806e3f6 | bellard | must be used (@xref{linux_compile}). |
269 | 0806e3f6 | bellard | |
270 | 0806e3f6 | bellard | @item |
271 | 285dc330 | bellard | @code{qemu} uses a software MMU. It is about @emph{two times |
272 | 285dc330 | bellard | slower} but gives a more accurate emulation. |
273 | 0806e3f6 | bellard | |
274 | 0806e3f6 | bellard | @end enumerate |
275 | 0806e3f6 | bellard | |
276 | 0806e3f6 | bellard | QEMU emulates the following PC peripherials: |
277 | 0806e3f6 | bellard | |
278 | 0806e3f6 | bellard | @itemize @minus |
279 | 0806e3f6 | bellard | @item |
280 | 0806e3f6 | bellard | VGA (hardware level, including all non standard modes) |
281 | 0806e3f6 | bellard | @item |
282 | 0806e3f6 | bellard | PS/2 mouse and keyboard |
283 | 0806e3f6 | bellard | @item |
284 | 181f1558 | bellard | 2 IDE interfaces with hard disk and CD-ROM support |
285 | 0806e3f6 | bellard | @item |
286 | 0806e3f6 | bellard | NE2000 network adapter (port=0x300, irq=9) |
287 | 0806e3f6 | bellard | @item |
288 | 181f1558 | bellard | Serial port |
289 | 181f1558 | bellard | @item |
290 | 181f1558 | bellard | Soundblaster 16 card |
291 | 0806e3f6 | bellard | @item |
292 | 0806e3f6 | bellard | PIC (interrupt controler) |
293 | 0806e3f6 | bellard | @item |
294 | 0806e3f6 | bellard | PIT (timers) |
295 | 0806e3f6 | bellard | @item |
296 | 0806e3f6 | bellard | CMOS memory |
297 | 0806e3f6 | bellard | @end itemize |
298 | 0806e3f6 | bellard | |
299 | 0806e3f6 | bellard | @c man end |
300 | 0806e3f6 | bellard | |
301 | 1eb20527 | bellard | @section Quick Start |
302 | 1eb20527 | bellard | |
303 | 285dc330 | bellard | Download and uncompress the linux image (@file{linux.img}) and type: |
304 | 0806e3f6 | bellard | |
305 | 0806e3f6 | bellard | @example |
306 | 285dc330 | bellard | qemu linux.img |
307 | 0806e3f6 | bellard | @end example |
308 | 0806e3f6 | bellard | |
309 | 0806e3f6 | bellard | Linux should boot and give you a prompt. |
310 | 0806e3f6 | bellard | |
311 | 0806e3f6 | bellard | @section Direct Linux Boot and Network emulation |
312 | 0806e3f6 | bellard | |
313 | 0806e3f6 | bellard | This section explains how to launch a Linux kernel inside QEMU without |
314 | 0806e3f6 | bellard | having to make a full bootable image. It is very useful for fast Linux |
315 | 0806e3f6 | bellard | kernel testing. The QEMU network configuration is also explained. |
316 | 1eb20527 | bellard | |
317 | 1eb20527 | bellard | @enumerate |
318 | 1eb20527 | bellard | @item |
319 | 0806e3f6 | bellard | Download the archive @file{linux-test-xxx.tar.gz} containing a Linux |
320 | 0806e3f6 | bellard | kernel and a disk image. |
321 | 1eb20527 | bellard | |
322 | 1eb20527 | bellard | @item Optional: If you want network support (for example to launch X11 examples), you |
323 | 0806e3f6 | bellard | must copy the script @file{qemu-ifup} in @file{/etc} and configure |
324 | 1eb20527 | bellard | properly @code{sudo} so that the command @code{ifconfig} contained in |
325 | 0806e3f6 | bellard | @file{qemu-ifup} can be executed as root. You must verify that your host |
326 | 1eb20527 | bellard | kernel supports the TUN/TAP network interfaces: the device |
327 | 1eb20527 | bellard | @file{/dev/net/tun} must be present. |
328 | 1eb20527 | bellard | |
329 | 1eb20527 | bellard | When network is enabled, there is a virtual network connection between |
330 | 1eb20527 | bellard | the host kernel and the emulated kernel. The emulated kernel is seen |
331 | 1eb20527 | bellard | from the host kernel at IP address 172.20.0.2 and the host kernel is |
332 | 1eb20527 | bellard | seen from the emulated kernel at IP address 172.20.0.1. |
333 | 1eb20527 | bellard | |
334 | 0806e3f6 | bellard | @item Launch @code{qemu.sh}. You should have the following output: |
335 | 1eb20527 | bellard | |
336 | 1eb20527 | bellard | @example |
337 | 0806e3f6 | bellard | > ./qemu.sh |
338 | 181f1558 | bellard | Connected to host network interface: tun0 |
339 | 181f1558 | bellard | Linux version 2.4.21 (bellard@voyager.localdomain) (gcc version 3.2.2 20030222 (Red Hat Linux 3.2.2-5)) #5 Tue Nov 11 18:18:53 CET 2003 |
340 | 1eb20527 | bellard | BIOS-provided physical RAM map: |
341 | 4690764b | bellard | BIOS-e801: 0000000000000000 - 000000000009f000 (usable) |
342 | 4690764b | bellard | BIOS-e801: 0000000000100000 - 0000000002000000 (usable) |
343 | 1eb20527 | bellard | 32MB LOWMEM available. |
344 | 1eb20527 | bellard | On node 0 totalpages: 8192 |
345 | 1eb20527 | bellard | zone(0): 4096 pages. |
346 | 1eb20527 | bellard | zone(1): 4096 pages. |
347 | 1eb20527 | bellard | zone(2): 0 pages. |
348 | 181f1558 | bellard | Kernel command line: root=/dev/hda sb=0x220,5,1,5 ide2=noprobe ide3=noprobe ide4=noprobe ide5=noprobe console=ttyS0 |
349 | 4690764b | bellard | ide_setup: ide2=noprobe |
350 | 4690764b | bellard | ide_setup: ide3=noprobe |
351 | 4690764b | bellard | ide_setup: ide4=noprobe |
352 | 4690764b | bellard | ide_setup: ide5=noprobe |
353 | 1eb20527 | bellard | Initializing CPU#0 |
354 | 181f1558 | bellard | Detected 2399.621 MHz processor. |
355 | 181f1558 | bellard | Console: colour EGA 80x25 |
356 | 181f1558 | bellard | Calibrating delay loop... 4744.80 BogoMIPS |
357 | 181f1558 | bellard | Memory: 28872k/32768k available (1210k kernel code, 3508k reserved, 266k data, 64k init, 0k highmem) |
358 | 1eb20527 | bellard | Dentry cache hash table entries: 4096 (order: 3, 32768 bytes) |
359 | 1eb20527 | bellard | Inode cache hash table entries: 2048 (order: 2, 16384 bytes) |
360 | 181f1558 | bellard | Mount cache hash table entries: 512 (order: 0, 4096 bytes) |
361 | 1eb20527 | bellard | Buffer-cache hash table entries: 1024 (order: 0, 4096 bytes) |
362 | 1eb20527 | bellard | Page-cache hash table entries: 8192 (order: 3, 32768 bytes) |
363 | 1eb20527 | bellard | CPU: Intel Pentium Pro stepping 03 |
364 | 1eb20527 | bellard | Checking 'hlt' instruction... OK. |
365 | 1eb20527 | bellard | POSIX conformance testing by UNIFIX |
366 | 1eb20527 | bellard | Linux NET4.0 for Linux 2.4 |
367 | 1eb20527 | bellard | Based upon Swansea University Computer Society NET3.039 |
368 | 1eb20527 | bellard | Initializing RT netlink socket |
369 | 1eb20527 | bellard | apm: BIOS not found. |
370 | 1eb20527 | bellard | Starting kswapd |
371 | 4690764b | bellard | Journalled Block Device driver loaded |
372 | 181f1558 | bellard | Detected PS/2 Mouse Port. |
373 | 1eb20527 | bellard | pty: 256 Unix98 ptys configured |
374 | 1eb20527 | bellard | Serial driver version 5.05c (2001-07-08) with no serial options enabled |
375 | 1eb20527 | bellard | ttyS00 at 0x03f8 (irq = 4) is a 16450 |
376 | 1eb20527 | bellard | ne.c:v1.10 9/23/94 Donald Becker (becker@scyld.com) |
377 | 1eb20527 | bellard | Last modified Nov 1, 2000 by Paul Gortmaker |
378 | 1eb20527 | bellard | NE*000 ethercard probe at 0x300: 52 54 00 12 34 56 |
379 | 1eb20527 | bellard | eth0: NE2000 found at 0x300, using IRQ 9. |
380 | 4690764b | bellard | RAMDISK driver initialized: 16 RAM disks of 4096K size 1024 blocksize |
381 | 181f1558 | bellard | Uniform Multi-Platform E-IDE driver Revision: 7.00beta4-2.4 |
382 | 181f1558 | bellard | ide: Assuming 50MHz system bus speed for PIO modes; override with idebus=xx |
383 | 181f1558 | bellard | hda: QEMU HARDDISK, ATA DISK drive |
384 | 181f1558 | bellard | ide0 at 0x1f0-0x1f7,0x3f6 on irq 14 |
385 | 181f1558 | bellard | hda: attached ide-disk driver. |
386 | 181f1558 | bellard | hda: 20480 sectors (10 MB) w/256KiB Cache, CHS=20/16/63 |
387 | 181f1558 | bellard | Partition check: |
388 | 181f1558 | bellard | hda: |
389 | 181f1558 | bellard | Soundblaster audio driver Copyright (C) by Hannu Savolainen 1993-1996 |
390 | 1eb20527 | bellard | NET4: Linux TCP/IP 1.0 for NET4.0 |
391 | 1eb20527 | bellard | IP Protocols: ICMP, UDP, TCP, IGMP |
392 | 1eb20527 | bellard | IP: routing cache hash table of 512 buckets, 4Kbytes |
393 | 4690764b | bellard | TCP: Hash tables configured (established 2048 bind 4096) |
394 | 1eb20527 | bellard | NET4: Unix domain sockets 1.0/SMP for Linux NET4.0. |
395 | 4690764b | bellard | EXT2-fs warning: mounting unchecked fs, running e2fsck is recommended |
396 | 1eb20527 | bellard | VFS: Mounted root (ext2 filesystem). |
397 | 181f1558 | bellard | Freeing unused kernel memory: 64k freed |
398 | 181f1558 | bellard | |
399 | 181f1558 | bellard | Linux version 2.4.21 (bellard@voyager.localdomain) (gcc version 3.2.2 20030222 (Red Hat Linux 3.2.2-5)) #5 Tue Nov 11 18:18:53 CET 2003 |
400 | 181f1558 | bellard | |
401 | 181f1558 | bellard | QEMU Linux test distribution (based on Redhat 9) |
402 | 181f1558 | bellard | |
403 | 181f1558 | bellard | Type 'exit' to halt the system |
404 | 181f1558 | bellard | |
405 | 181f1558 | bellard | sh-2.05b# |
406 | 1eb20527 | bellard | @end example |
407 | 1eb20527 | bellard | |
408 | 1eb20527 | bellard | @item |
409 | 1eb20527 | bellard | Then you can play with the kernel inside the virtual serial console. You |
410 | 1eb20527 | bellard | can launch @code{ls} for example. Type @key{Ctrl-a h} to have an help |
411 | 1eb20527 | bellard | about the keys you can type inside the virtual serial console. In |
412 | d5a0b50c | bellard | particular, use @key{Ctrl-a x} to exit QEMU and use @key{Ctrl-a b} as |
413 | d5a0b50c | bellard | the Magic SysRq key. |
414 | 1eb20527 | bellard | |
415 | 1eb20527 | bellard | @item |
416 | 1eb20527 | bellard | If the network is enabled, launch the script @file{/etc/linuxrc} in the |
417 | 1eb20527 | bellard | emulator (don't forget the leading dot): |
418 | 1eb20527 | bellard | @example |
419 | 1eb20527 | bellard | . /etc/linuxrc |
420 | 1eb20527 | bellard | @end example |
421 | 1eb20527 | bellard | |
422 | 1eb20527 | bellard | Then enable X11 connections on your PC from the emulated Linux: |
423 | 1eb20527 | bellard | @example |
424 | 1eb20527 | bellard | xhost +172.20.0.2 |
425 | 1eb20527 | bellard | @end example |
426 | 1eb20527 | bellard | |
427 | 1eb20527 | bellard | You can now launch @file{xterm} or @file{xlogo} and verify that you have |
428 | 1eb20527 | bellard | a real Virtual Linux system ! |
429 | 1eb20527 | bellard | |
430 | 1eb20527 | bellard | @end enumerate |
431 | 1eb20527 | bellard | |
432 | d5a0b50c | bellard | NOTES: |
433 | d5a0b50c | bellard | @enumerate |
434 | d5a0b50c | bellard | @item |
435 | 0806e3f6 | bellard | A 2.5.74 kernel is also included in the archive. Just |
436 | 0806e3f6 | bellard | replace the bzImage in qemu.sh to try it. |
437 | d5a0b50c | bellard | |
438 | d5a0b50c | bellard | @item |
439 | 9d4520d0 | bellard | qemu creates a temporary file in @var{$QEMU_TMPDIR} (@file{/tmp} is the |
440 | d5a0b50c | bellard | default) containing all the simulated PC memory. If possible, try to use |
441 | d5a0b50c | bellard | a temporary directory using the tmpfs filesystem to avoid too many |
442 | d5a0b50c | bellard | unnecessary disk accesses. |
443 | d5a0b50c | bellard | |
444 | d5a0b50c | bellard | @item |
445 | 9d4520d0 | bellard | In order to exit cleanly from qemu, you can do a @emph{shutdown} inside |
446 | 9d4520d0 | bellard | qemu. qemu will automatically exit when the Linux shutdown is done. |
447 | 4690764b | bellard | |
448 | 4690764b | bellard | @item |
449 | 4690764b | bellard | You can boot slightly faster by disabling the probe of non present IDE |
450 | 4690764b | bellard | interfaces. To do so, add the following options on the kernel command |
451 | 4690764b | bellard | line: |
452 | 4690764b | bellard | @example |
453 | 4690764b | bellard | ide1=noprobe ide2=noprobe ide3=noprobe ide4=noprobe ide5=noprobe |
454 | 4690764b | bellard | @end example |
455 | 4690764b | bellard | |
456 | 4690764b | bellard | @item |
457 | 4690764b | bellard | The example disk image is a modified version of the one made by Kevin |
458 | 1eb20527 | bellard | Lawton for the plex86 Project (@url{www.plex86.org}). |
459 | 1eb20527 | bellard | |
460 | d5a0b50c | bellard | @end enumerate |
461 | d5a0b50c | bellard | |
462 | ec410fc9 | bellard | @section Invocation |
463 | ec410fc9 | bellard | |
464 | ec410fc9 | bellard | @example |
465 | 0806e3f6 | bellard | @c man begin SYNOPSIS |
466 | 0806e3f6 | bellard | usage: qemu [options] [disk_image] |
467 | 0806e3f6 | bellard | @c man end |
468 | ec410fc9 | bellard | @end example |
469 | ec410fc9 | bellard | |
470 | 0806e3f6 | bellard | @c man begin OPTIONS |
471 | 9d4520d0 | bellard | @var{disk_image} is a raw hard disk image for IDE hard disk 0. |
472 | ec410fc9 | bellard | |
473 | ec410fc9 | bellard | General options: |
474 | ec410fc9 | bellard | @table @option |
475 | 2be3bc02 | bellard | @item -fda file |
476 | 2be3bc02 | bellard | @item -fdb file |
477 | 2be3bc02 | bellard | Use @var{file} as floppy disk 0/1 image (@xref{disk_images}). |
478 | 2be3bc02 | bellard | |
479 | ec410fc9 | bellard | @item -hda file |
480 | ec410fc9 | bellard | @item -hdb file |
481 | 181f1558 | bellard | @item -hdc file |
482 | 181f1558 | bellard | @item -hdd file |
483 | 2be3bc02 | bellard | Use @var{file} as hard disk 0, 1, 2 or 3 image (@xref{disk_images}). |
484 | 1f47a922 | bellard | |
485 | 181f1558 | bellard | @item -cdrom file |
486 | 181f1558 | bellard | Use @var{file} as CD-ROM image (you cannot use @option{-hdc} and and |
487 | 181f1558 | bellard | @option{-cdrom} at the same time). |
488 | 181f1558 | bellard | |
489 | 2be3bc02 | bellard | @item -boot [a|b|c|d] |
490 | 2be3bc02 | bellard | Boot on floppy (a, b), hard disk (c) or CD-ROM (d). Hard disk boot is |
491 | 2be3bc02 | bellard | the default. |
492 | 1f47a922 | bellard | |
493 | 181f1558 | bellard | @item -snapshot |
494 | 1f47a922 | bellard | Write to temporary files instead of disk image files. In this case, |
495 | 1f47a922 | bellard | the raw disk image you use is not written back. You can however force |
496 | 1f47a922 | bellard | the write back by pressing @key{C-a s} (@xref{disk_images}). |
497 | ec410fc9 | bellard | |
498 | ec410fc9 | bellard | @item -m megs |
499 | ec410fc9 | bellard | Set virtual RAM size to @var{megs} megabytes. |
500 | ec410fc9 | bellard | |
501 | ec410fc9 | bellard | @item -n script |
502 | 9d4520d0 | bellard | Set network init script [default=/etc/qemu-ifup]. This script is |
503 | ec410fc9 | bellard | launched to configure the host network interface (usually tun0) |
504 | ec410fc9 | bellard | corresponding to the virtual NE2000 card. |
505 | 4690764b | bellard | |
506 | 4690764b | bellard | @item -initrd file |
507 | 0806e3f6 | bellard | Use @var{file} as initial ram disk. |
508 | 0806e3f6 | bellard | |
509 | 0806e3f6 | bellard | @item -tun-fd fd |
510 | 0806e3f6 | bellard | Assumes @var{fd} talks to tap/tun and use it. Read |
511 | 0806e3f6 | bellard | @url{http://bellard.org/qemu/tetrinet.html} to have an example of its |
512 | 0806e3f6 | bellard | use. |
513 | 0806e3f6 | bellard | |
514 | 0806e3f6 | bellard | @item -nographic |
515 | 0806e3f6 | bellard | |
516 | 0806e3f6 | bellard | Normally, QEMU uses SDL to display the VGA output. With this option, |
517 | 0806e3f6 | bellard | you can totally disable graphical output so that QEMU is a simple |
518 | 0806e3f6 | bellard | command line application. The emulated serial port is redirected on |
519 | 0806e3f6 | bellard | the console. Therefore, you can still use QEMU to debug a Linux kernel |
520 | 0806e3f6 | bellard | with a serial console. |
521 | 0806e3f6 | bellard | |
522 | 0806e3f6 | bellard | @end table |
523 | 0806e3f6 | bellard | |
524 | 0806e3f6 | bellard | Linux boot specific (does not require a full PC boot with a BIOS): |
525 | 0806e3f6 | bellard | @table @option |
526 | 0806e3f6 | bellard | |
527 | 0806e3f6 | bellard | @item -kernel bzImage |
528 | 0806e3f6 | bellard | Use @var{bzImage} as kernel image. |
529 | 0806e3f6 | bellard | |
530 | 0806e3f6 | bellard | @item -append cmdline |
531 | 0806e3f6 | bellard | Use @var{cmdline} as kernel command line |
532 | 0806e3f6 | bellard | |
533 | 0806e3f6 | bellard | @item -initrd file |
534 | 0806e3f6 | bellard | Use @var{file} as initial ram disk. |
535 | 0806e3f6 | bellard | |
536 | ec410fc9 | bellard | @end table |
537 | ec410fc9 | bellard | |
538 | ec410fc9 | bellard | Debug options: |
539 | ec410fc9 | bellard | @table @option |
540 | ec410fc9 | bellard | @item -s |
541 | 0806e3f6 | bellard | Wait gdb connection to port 1234 (@xref{gdb_usage}). |
542 | ec410fc9 | bellard | @item -p port |
543 | ec410fc9 | bellard | Change gdb connection port. |
544 | ec410fc9 | bellard | @item -d |
545 | 9d4520d0 | bellard | Output log in /tmp/qemu.log |
546 | ec410fc9 | bellard | @end table |
547 | ec410fc9 | bellard | |
548 | ec410fc9 | bellard | During emulation, use @key{C-a h} to get terminal commands: |
549 | ec410fc9 | bellard | |
550 | ec410fc9 | bellard | @table @key |
551 | ec410fc9 | bellard | @item C-a h |
552 | ec410fc9 | bellard | Print this help |
553 | ec410fc9 | bellard | @item C-a x |
554 | ec410fc9 | bellard | Exit emulatior |
555 | 1f47a922 | bellard | @item C-a s |
556 | 1f47a922 | bellard | Save disk data back to file (if -snapshot) |
557 | 1f47a922 | bellard | @item C-a b |
558 | ec410fc9 | bellard | Send break (magic sysrq) |
559 | 1f47a922 | bellard | @item C-a C-a |
560 | ec410fc9 | bellard | Send C-a |
561 | ec410fc9 | bellard | @end table |
562 | 0806e3f6 | bellard | @c man end |
563 | 0806e3f6 | bellard | |
564 | 0806e3f6 | bellard | @ignore |
565 | 0806e3f6 | bellard | |
566 | 0806e3f6 | bellard | @setfilename qemu |
567 | 0806e3f6 | bellard | @settitle QEMU System Emulator |
568 | 0806e3f6 | bellard | |
569 | 0806e3f6 | bellard | @c man begin SEEALSO |
570 | 0806e3f6 | bellard | The HTML documentation of QEMU for more precise information and Linux |
571 | 0806e3f6 | bellard | user mode emulator invocation. |
572 | 0806e3f6 | bellard | @c man end |
573 | 0806e3f6 | bellard | |
574 | 0806e3f6 | bellard | @c man begin AUTHOR |
575 | 0806e3f6 | bellard | Fabrice Bellard |
576 | 0806e3f6 | bellard | @c man end |
577 | 0806e3f6 | bellard | |
578 | 0806e3f6 | bellard | @end ignore |
579 | ec410fc9 | bellard | |
580 | 0806e3f6 | bellard | @end ignore |
581 | 1f47a922 | bellard | @node disk_images |
582 | 1f47a922 | bellard | @section Disk Images |
583 | 1f47a922 | bellard | |
584 | 1f47a922 | bellard | @subsection Raw disk images |
585 | 1f47a922 | bellard | |
586 | 1f47a922 | bellard | The disk images can simply be raw images of the hard disk. You can |
587 | 1f47a922 | bellard | create them with the command: |
588 | 1f47a922 | bellard | @example |
589 | 1f47a922 | bellard | dd if=/dev/zero of=myimage bs=1024 count=mysize |
590 | 1f47a922 | bellard | @end example |
591 | 1f47a922 | bellard | where @var{myimage} is the image filename and @var{mysize} is its size |
592 | 1f47a922 | bellard | in kilobytes. |
593 | 1f47a922 | bellard | |
594 | 1f47a922 | bellard | @subsection Snapshot mode |
595 | 1f47a922 | bellard | |
596 | 1f47a922 | bellard | If you use the option @option{-snapshot}, all disk images are |
597 | 1f47a922 | bellard | considered as read only. When sectors in written, they are written in |
598 | 1f47a922 | bellard | a temporary file created in @file{/tmp}. You can however force the |
599 | 1f47a922 | bellard | write back to the raw disk images by pressing @key{C-a s}. |
600 | 1f47a922 | bellard | |
601 | 1f47a922 | bellard | NOTE: The snapshot mode only works with raw disk images. |
602 | 1f47a922 | bellard | |
603 | 1f47a922 | bellard | @subsection Copy On Write disk images |
604 | 1f47a922 | bellard | |
605 | 1f47a922 | bellard | QEMU also supports user mode Linux |
606 | 1f47a922 | bellard | (@url{http://user-mode-linux.sourceforge.net/}) Copy On Write (COW) |
607 | 1f47a922 | bellard | disk images. The COW disk images are much smaller than normal images |
608 | 1f47a922 | bellard | as they store only modified sectors. They also permit the use of the |
609 | 1f47a922 | bellard | same disk image template for many users. |
610 | 1f47a922 | bellard | |
611 | 1f47a922 | bellard | To create a COW disk images, use the command: |
612 | 1f47a922 | bellard | |
613 | 1f47a922 | bellard | @example |
614 | 0806e3f6 | bellard | qemu-mkcow -f myrawimage.bin mycowimage.cow |
615 | 1f47a922 | bellard | @end example |
616 | 1f47a922 | bellard | |
617 | 1f47a922 | bellard | @file{myrawimage.bin} is a raw image you want to use as original disk |
618 | 1f47a922 | bellard | image. It will never be written to. |
619 | 1f47a922 | bellard | |
620 | 1f47a922 | bellard | @file{mycowimage.cow} is the COW disk image which is created by |
621 | 0806e3f6 | bellard | @code{qemu-mkcow}. You can use it directly with the @option{-hdx} |
622 | 1f47a922 | bellard | options. You must not modify the original raw disk image if you use |
623 | 1f47a922 | bellard | COW images, as COW images only store the modified sectors from the raw |
624 | 1f47a922 | bellard | disk image. QEMU stores the original raw disk image name and its |
625 | 1f47a922 | bellard | modified time in the COW disk image so that chances of mistakes are |
626 | 1f47a922 | bellard | reduced. |
627 | 1f47a922 | bellard | |
628 | 9d0fe224 | bellard | If the raw disk image is not read-only, by pressing @key{C-a s} you |
629 | 9d0fe224 | bellard | can flush the COW disk image back into the raw disk image, as in |
630 | 9d0fe224 | bellard | snapshot mode. |
631 | 1f47a922 | bellard | |
632 | 1f47a922 | bellard | COW disk images can also be created without a corresponding raw disk |
633 | 1f47a922 | bellard | image. It is useful to have a big initial virtual disk image without |
634 | 1f47a922 | bellard | using much disk space. Use: |
635 | 1f47a922 | bellard | |
636 | 1f47a922 | bellard | @example |
637 | 0806e3f6 | bellard | qemu-mkcow mycowimage.cow 1024 |
638 | 1f47a922 | bellard | @end example |
639 | 1f47a922 | bellard | |
640 | 1f47a922 | bellard | to create a 1 gigabyte empty COW disk image. |
641 | 1f47a922 | bellard | |
642 | 1f47a922 | bellard | NOTES: |
643 | 1f47a922 | bellard | @enumerate |
644 | 1f47a922 | bellard | @item |
645 | 1f47a922 | bellard | COW disk images must be created on file systems supporting |
646 | 1f47a922 | bellard | @emph{holes} such as ext2 or ext3. |
647 | 1f47a922 | bellard | @item |
648 | 1f47a922 | bellard | Since holes are used, the displayed size of the COW disk image is not |
649 | 1f47a922 | bellard | the real one. To know it, use the @code{ls -ls} command. |
650 | 1f47a922 | bellard | @end enumerate |
651 | 1f47a922 | bellard | |
652 | 0806e3f6 | bellard | @node linux_compile |
653 | 4690764b | bellard | @section Linux Kernel Compilation |
654 | 4690764b | bellard | |
655 | 285dc330 | bellard | You can use any linux kernel with QEMU. However, if you want to use |
656 | 285dc330 | bellard | @code{qemu-fast} to get maximum performances, you should make the |
657 | 285dc330 | bellard | following changes to the Linux kernel (only 2.4.x and 2.5.x were |
658 | 285dc330 | bellard | tested): |
659 | 1eb20527 | bellard | |
660 | 4690764b | bellard | @enumerate |
661 | 4690764b | bellard | @item |
662 | 4690764b | bellard | The kernel must be mapped at 0x90000000 (the default is |
663 | 4690764b | bellard | 0xc0000000). You must modify only two lines in the kernel source: |
664 | 1eb20527 | bellard | |
665 | 4690764b | bellard | In @file{include/asm/page.h}, replace |
666 | 1eb20527 | bellard | @example |
667 | 1eb20527 | bellard | #define __PAGE_OFFSET (0xc0000000) |
668 | 1eb20527 | bellard | @end example |
669 | 1eb20527 | bellard | by |
670 | 1eb20527 | bellard | @example |
671 | 1eb20527 | bellard | #define __PAGE_OFFSET (0x90000000) |
672 | 1eb20527 | bellard | @end example |
673 | 1eb20527 | bellard | |
674 | 4690764b | bellard | And in @file{arch/i386/vmlinux.lds}, replace |
675 | 1eb20527 | bellard | @example |
676 | 1eb20527 | bellard | . = 0xc0000000 + 0x100000; |
677 | 1eb20527 | bellard | @end example |
678 | 1eb20527 | bellard | by |
679 | 1eb20527 | bellard | @example |
680 | 1eb20527 | bellard | . = 0x90000000 + 0x100000; |
681 | 1eb20527 | bellard | @end example |
682 | 1eb20527 | bellard | |
683 | 4690764b | bellard | @item |
684 | 4690764b | bellard | If you want to enable SMP (Symmetric Multi-Processing) support, you |
685 | 4690764b | bellard | must make the following change in @file{include/asm/fixmap.h}. Replace |
686 | 1eb20527 | bellard | @example |
687 | 4690764b | bellard | #define FIXADDR_TOP (0xffffX000UL) |
688 | 1eb20527 | bellard | @end example |
689 | 4690764b | bellard | by |
690 | 4690764b | bellard | @example |
691 | 4690764b | bellard | #define FIXADDR_TOP (0xa7ffX000UL) |
692 | 4690764b | bellard | @end example |
693 | 4690764b | bellard | (X is 'e' or 'f' depending on the kernel version). Although you can |
694 | 4690764b | bellard | use an SMP kernel with QEMU, it only supports one CPU. |
695 | 1eb20527 | bellard | |
696 | 4690764b | bellard | @item |
697 | d5a0b50c | bellard | If you are not using a 2.5 kernel as host kernel but if you use a target |
698 | d5a0b50c | bellard | 2.5 kernel, you must also ensure that the 'HZ' define is set to 100 |
699 | d5a0b50c | bellard | (1000 is the default) as QEMU cannot currently emulate timers at |
700 | d5a0b50c | bellard | frequencies greater than 100 Hz on host Linux systems < 2.5. In |
701 | 4690764b | bellard | @file{include/asm/param.h}, replace: |
702 | d5a0b50c | bellard | |
703 | d5a0b50c | bellard | @example |
704 | d5a0b50c | bellard | # define HZ 1000 /* Internal kernel timer frequency */ |
705 | d5a0b50c | bellard | @end example |
706 | d5a0b50c | bellard | by |
707 | d5a0b50c | bellard | @example |
708 | d5a0b50c | bellard | # define HZ 100 /* Internal kernel timer frequency */ |
709 | d5a0b50c | bellard | @end example |
710 | d5a0b50c | bellard | |
711 | 4690764b | bellard | @end enumerate |
712 | 4690764b | bellard | |
713 | 4690764b | bellard | The file config-2.x.x gives the configuration of the example kernels. |
714 | 4690764b | bellard | |
715 | 4690764b | bellard | Just type |
716 | 4690764b | bellard | @example |
717 | 4690764b | bellard | make bzImage |
718 | 4690764b | bellard | @end example |
719 | 4690764b | bellard | |
720 | 4690764b | bellard | As you would do to make a real kernel. Then you can use with QEMU |
721 | 4690764b | bellard | exactly the same kernel as you would boot on your PC (in |
722 | 4690764b | bellard | @file{arch/i386/boot/bzImage}). |
723 | da415d54 | bellard | |
724 | 0806e3f6 | bellard | @node gdb_usage |
725 | da415d54 | bellard | @section GDB usage |
726 | da415d54 | bellard | |
727 | da415d54 | bellard | QEMU has a primitive support to work with gdb, so that you can do |
728 | 0806e3f6 | bellard | 'Ctrl-C' while the virtual machine is running and inspect its state. |
729 | da415d54 | bellard | |
730 | 9d4520d0 | bellard | In order to use gdb, launch qemu with the '-s' option. It will wait for a |
731 | da415d54 | bellard | gdb connection: |
732 | da415d54 | bellard | @example |
733 | 6c9bf893 | bellard | > qemu -s -kernel arch/i386/boot/bzImage -hda root-2.4.20.img -append "root=/dev/hda" |
734 | da415d54 | bellard | Connected to host network interface: tun0 |
735 | da415d54 | bellard | Waiting gdb connection on port 1234 |
736 | da415d54 | bellard | @end example |
737 | da415d54 | bellard | |
738 | da415d54 | bellard | Then launch gdb on the 'vmlinux' executable: |
739 | da415d54 | bellard | @example |
740 | da415d54 | bellard | > gdb vmlinux |
741 | da415d54 | bellard | @end example |
742 | da415d54 | bellard | |
743 | da415d54 | bellard | In gdb, connect to QEMU: |
744 | da415d54 | bellard | @example |
745 | 6c9bf893 | bellard | (gdb) target remote localhost:1234 |
746 | da415d54 | bellard | @end example |
747 | da415d54 | bellard | |
748 | da415d54 | bellard | Then you can use gdb normally. For example, type 'c' to launch the kernel: |
749 | da415d54 | bellard | @example |
750 | da415d54 | bellard | (gdb) c |
751 | da415d54 | bellard | @end example |
752 | da415d54 | bellard | |
753 | 0806e3f6 | bellard | Here are some useful tips in order to use gdb on system code: |
754 | 0806e3f6 | bellard | |
755 | 0806e3f6 | bellard | @enumerate |
756 | 0806e3f6 | bellard | @item |
757 | 0806e3f6 | bellard | Use @code{info reg} to display all the CPU registers. |
758 | 0806e3f6 | bellard | @item |
759 | 0806e3f6 | bellard | Use @code{x/10i $eip} to display the code at the PC position. |
760 | 0806e3f6 | bellard | @item |
761 | 0806e3f6 | bellard | Use @code{set architecture i8086} to dump 16 bit code. Then use |
762 | 0806e3f6 | bellard | @code{x/10i $cs*16+*eip} to dump the code at the PC position. |
763 | 0806e3f6 | bellard | @end enumerate |
764 | 0806e3f6 | bellard | |
765 | 386405f7 | bellard | @chapter QEMU Internals |
766 | 386405f7 | bellard | |
767 | 386405f7 | bellard | @section QEMU compared to other emulators |
768 | 386405f7 | bellard | |
769 | 1eb20527 | bellard | Like bochs [3], QEMU emulates an x86 CPU. But QEMU is much faster than |
770 | 1eb20527 | bellard | bochs as it uses dynamic compilation and because it uses the host MMU to |
771 | 1eb20527 | bellard | simulate the x86 MMU. The downside is that currently the emulation is |
772 | 1eb20527 | bellard | not as accurate as bochs (for example, you cannot currently run Windows |
773 | 1eb20527 | bellard | inside QEMU). |
774 | 386405f7 | bellard | |
775 | 386405f7 | bellard | Like Valgrind [2], QEMU does user space emulation and dynamic |
776 | 386405f7 | bellard | translation. Valgrind is mainly a memory debugger while QEMU has no |
777 | 1eb20527 | bellard | support for it (QEMU could be used to detect out of bound memory |
778 | 1eb20527 | bellard | accesses as Valgrind, but it has no support to track uninitialised data |
779 | d5a0b50c | bellard | as Valgrind does). The Valgrind dynamic translator generates better code |
780 | 1eb20527 | bellard | than QEMU (in particular it does register allocation) but it is closely |
781 | d5a0b50c | bellard | tied to an x86 host and target and has no support for precise exceptions |
782 | 1eb20527 | bellard | and system emulation. |
783 | 1eb20527 | bellard | |
784 | 1eb20527 | bellard | EM86 [4] is the closest project to user space QEMU (and QEMU still uses |
785 | 1eb20527 | bellard | some of its code, in particular the ELF file loader). EM86 was limited |
786 | 1eb20527 | bellard | to an alpha host and used a proprietary and slow interpreter (the |
787 | 1eb20527 | bellard | interpreter part of the FX!32 Digital Win32 code translator [5]). |
788 | 386405f7 | bellard | |
789 | fd429f2f | bellard | TWIN [6] is a Windows API emulator like Wine. It is less accurate than |
790 | fd429f2f | bellard | Wine but includes a protected mode x86 interpreter to launch x86 Windows |
791 | fd429f2f | bellard | executables. Such an approach as greater potential because most of the |
792 | fd429f2f | bellard | Windows API is executed natively but it is far more difficult to develop |
793 | fd429f2f | bellard | because all the data structures and function parameters exchanged |
794 | fd429f2f | bellard | between the API and the x86 code must be converted. |
795 | fd429f2f | bellard | |
796 | 1eb20527 | bellard | User mode Linux [7] was the only solution before QEMU to launch a Linux |
797 | 1eb20527 | bellard | kernel as a process while not needing any host kernel patches. However, |
798 | 1eb20527 | bellard | user mode Linux requires heavy kernel patches while QEMU accepts |
799 | 1eb20527 | bellard | unpatched Linux kernels. It would be interesting to compare the |
800 | 1eb20527 | bellard | performance of the two approaches. |
801 | 1eb20527 | bellard | |
802 | 1eb20527 | bellard | The new Plex86 [8] PC virtualizer is done in the same spirit as the QEMU |
803 | 1eb20527 | bellard | system emulator. It requires a patched Linux kernel to work (you cannot |
804 | 1eb20527 | bellard | launch the same kernel on your PC), but the patches are really small. As |
805 | 1eb20527 | bellard | it is a PC virtualizer (no emulation is done except for some priveledged |
806 | 1eb20527 | bellard | instructions), it has the potential of being faster than QEMU. The |
807 | d5a0b50c | bellard | downside is that a complicated (and potentially unsafe) host kernel |
808 | d5a0b50c | bellard | patch is needed. |
809 | 1eb20527 | bellard | |
810 | 386405f7 | bellard | @section Portable dynamic translation |
811 | 386405f7 | bellard | |
812 | 386405f7 | bellard | QEMU is a dynamic translator. When it first encounters a piece of code, |
813 | 386405f7 | bellard | it converts it to the host instruction set. Usually dynamic translators |
814 | 322d0c66 | bellard | are very complicated and highly CPU dependent. QEMU uses some tricks |
815 | 386405f7 | bellard | which make it relatively easily portable and simple while achieving good |
816 | 386405f7 | bellard | performances. |
817 | 386405f7 | bellard | |
818 | 386405f7 | bellard | The basic idea is to split every x86 instruction into fewer simpler |
819 | 386405f7 | bellard | instructions. Each simple instruction is implemented by a piece of C |
820 | 386405f7 | bellard | code (see @file{op-i386.c}). Then a compile time tool (@file{dyngen}) |
821 | 386405f7 | bellard | takes the corresponding object file (@file{op-i386.o}) to generate a |
822 | 386405f7 | bellard | dynamic code generator which concatenates the simple instructions to |
823 | 386405f7 | bellard | build a function (see @file{op-i386.h:dyngen_code()}). |
824 | 386405f7 | bellard | |
825 | 386405f7 | bellard | In essence, the process is similar to [1], but more work is done at |
826 | 386405f7 | bellard | compile time. |
827 | 386405f7 | bellard | |
828 | 386405f7 | bellard | A key idea to get optimal performances is that constant parameters can |
829 | 386405f7 | bellard | be passed to the simple operations. For that purpose, dummy ELF |
830 | 386405f7 | bellard | relocations are generated with gcc for each constant parameter. Then, |
831 | 386405f7 | bellard | the tool (@file{dyngen}) can locate the relocations and generate the |
832 | 386405f7 | bellard | appriopriate C code to resolve them when building the dynamic code. |
833 | 386405f7 | bellard | |
834 | 386405f7 | bellard | That way, QEMU is no more difficult to port than a dynamic linker. |
835 | 386405f7 | bellard | |
836 | 386405f7 | bellard | To go even faster, GCC static register variables are used to keep the |
837 | 386405f7 | bellard | state of the virtual CPU. |
838 | 386405f7 | bellard | |
839 | 386405f7 | bellard | @section Register allocation |
840 | 386405f7 | bellard | |
841 | 386405f7 | bellard | Since QEMU uses fixed simple instructions, no efficient register |
842 | 386405f7 | bellard | allocation can be done. However, because RISC CPUs have a lot of |
843 | 386405f7 | bellard | register, most of the virtual CPU state can be put in registers without |
844 | 386405f7 | bellard | doing complicated register allocation. |
845 | 386405f7 | bellard | |
846 | 386405f7 | bellard | @section Condition code optimisations |
847 | 386405f7 | bellard | |
848 | 386405f7 | bellard | Good CPU condition codes emulation (@code{EFLAGS} register on x86) is a |
849 | 386405f7 | bellard | critical point to get good performances. QEMU uses lazy condition code |
850 | 386405f7 | bellard | evaluation: instead of computing the condition codes after each x86 |
851 | fd429f2f | bellard | instruction, it just stores one operand (called @code{CC_SRC}), the |
852 | 386405f7 | bellard | result (called @code{CC_DST}) and the type of operation (called |
853 | 386405f7 | bellard | @code{CC_OP}). |
854 | 386405f7 | bellard | |
855 | 386405f7 | bellard | @code{CC_OP} is almost never explicitely set in the generated code |
856 | 386405f7 | bellard | because it is known at translation time. |
857 | 386405f7 | bellard | |
858 | 386405f7 | bellard | In order to increase performances, a backward pass is performed on the |
859 | 386405f7 | bellard | generated simple instructions (see |
860 | 386405f7 | bellard | @code{translate-i386.c:optimize_flags()}). When it can be proved that |
861 | 386405f7 | bellard | the condition codes are not needed by the next instructions, no |
862 | 386405f7 | bellard | condition codes are computed at all. |
863 | 386405f7 | bellard | |
864 | fd429f2f | bellard | @section CPU state optimisations |
865 | 386405f7 | bellard | |
866 | 386405f7 | bellard | The x86 CPU has many internal states which change the way it evaluates |
867 | 386405f7 | bellard | instructions. In order to achieve a good speed, the translation phase |
868 | 386405f7 | bellard | considers that some state information of the virtual x86 CPU cannot |
869 | 386405f7 | bellard | change in it. For example, if the SS, DS and ES segments have a zero |
870 | 386405f7 | bellard | base, then the translator does not even generate an addition for the |
871 | 386405f7 | bellard | segment base. |
872 | 386405f7 | bellard | |
873 | 386405f7 | bellard | [The FPU stack pointer register is not handled that way yet]. |
874 | 386405f7 | bellard | |
875 | 386405f7 | bellard | @section Translation cache |
876 | 386405f7 | bellard | |
877 | 386405f7 | bellard | A 2MByte cache holds the most recently used translations. For |
878 | 386405f7 | bellard | simplicity, it is completely flushed when it is full. A translation unit |
879 | 386405f7 | bellard | contains just a single basic block (a block of x86 instructions |
880 | 386405f7 | bellard | terminated by a jump or by a virtual CPU state change which the |
881 | 386405f7 | bellard | translator cannot deduce statically). |
882 | 386405f7 | bellard | |
883 | df0f11a0 | bellard | @section Direct block chaining |
884 | df0f11a0 | bellard | |
885 | df0f11a0 | bellard | After each translated basic block is executed, QEMU uses the simulated |
886 | df0f11a0 | bellard | Program Counter (PC) and other cpu state informations (such as the CS |
887 | df0f11a0 | bellard | segment base value) to find the next basic block. |
888 | df0f11a0 | bellard | |
889 | df0f11a0 | bellard | In order to accelerate the most common cases where the new simulated PC |
890 | df0f11a0 | bellard | is known, QEMU can patch a basic block so that it jumps directly to the |
891 | df0f11a0 | bellard | next one. |
892 | df0f11a0 | bellard | |
893 | df0f11a0 | bellard | The most portable code uses an indirect jump. An indirect jump makes it |
894 | df0f11a0 | bellard | easier to make the jump target modification atomic. On some |
895 | df0f11a0 | bellard | architectures (such as PowerPC), the @code{JUMP} opcode is directly |
896 | df0f11a0 | bellard | patched so that the block chaining has no overhead. |
897 | df0f11a0 | bellard | |
898 | df0f11a0 | bellard | @section Self-modifying code and translated code invalidation |
899 | df0f11a0 | bellard | |
900 | df0f11a0 | bellard | Self-modifying code is a special challenge in x86 emulation because no |
901 | df0f11a0 | bellard | instruction cache invalidation is signaled by the application when code |
902 | df0f11a0 | bellard | is modified. |
903 | df0f11a0 | bellard | |
904 | df0f11a0 | bellard | When translated code is generated for a basic block, the corresponding |
905 | df0f11a0 | bellard | host page is write protected if it is not already read-only (with the |
906 | df0f11a0 | bellard | system call @code{mprotect()}). Then, if a write access is done to the |
907 | df0f11a0 | bellard | page, Linux raises a SEGV signal. QEMU then invalidates all the |
908 | df0f11a0 | bellard | translated code in the page and enables write accesses to the page. |
909 | df0f11a0 | bellard | |
910 | df0f11a0 | bellard | Correct translated code invalidation is done efficiently by maintaining |
911 | df0f11a0 | bellard | a linked list of every translated block contained in a given page. Other |
912 | df0f11a0 | bellard | linked lists are also maintained to undo direct block chaining. |
913 | df0f11a0 | bellard | |
914 | 4690764b | bellard | Although the overhead of doing @code{mprotect()} calls is important, |
915 | df0f11a0 | bellard | most MSDOS programs can be emulated at reasonnable speed with QEMU and |
916 | df0f11a0 | bellard | DOSEMU. |
917 | df0f11a0 | bellard | |
918 | df0f11a0 | bellard | Note that QEMU also invalidates pages of translated code when it detects |
919 | df0f11a0 | bellard | that memory mappings are modified with @code{mmap()} or @code{munmap()}. |
920 | 386405f7 | bellard | |
921 | 386405f7 | bellard | @section Exception support |
922 | 386405f7 | bellard | |
923 | 386405f7 | bellard | longjmp() is used when an exception such as division by zero is |
924 | df0f11a0 | bellard | encountered. |
925 | 386405f7 | bellard | |
926 | df0f11a0 | bellard | The host SIGSEGV and SIGBUS signal handlers are used to get invalid |
927 | df0f11a0 | bellard | memory accesses. The exact CPU state can be retrieved because all the |
928 | df0f11a0 | bellard | x86 registers are stored in fixed host registers. The simulated program |
929 | df0f11a0 | bellard | counter is found by retranslating the corresponding basic block and by |
930 | df0f11a0 | bellard | looking where the host program counter was at the exception point. |
931 | df0f11a0 | bellard | |
932 | df0f11a0 | bellard | The virtual CPU cannot retrieve the exact @code{EFLAGS} register because |
933 | df0f11a0 | bellard | in some cases it is not computed because of condition code |
934 | df0f11a0 | bellard | optimisations. It is not a big concern because the emulated code can |
935 | df0f11a0 | bellard | still be restarted in any cases. |
936 | 386405f7 | bellard | |
937 | 386405f7 | bellard | @section Linux system call translation |
938 | 386405f7 | bellard | |
939 | 386405f7 | bellard | QEMU includes a generic system call translator for Linux. It means that |
940 | 386405f7 | bellard | the parameters of the system calls can be converted to fix the |
941 | 386405f7 | bellard | endianness and 32/64 bit issues. The IOCTLs are converted with a generic |
942 | 386405f7 | bellard | type description system (see @file{ioctls.h} and @file{thunk.c}). |
943 | 386405f7 | bellard | |
944 | df0f11a0 | bellard | QEMU supports host CPUs which have pages bigger than 4KB. It records all |
945 | df0f11a0 | bellard | the mappings the process does and try to emulated the @code{mmap()} |
946 | df0f11a0 | bellard | system calls in cases where the host @code{mmap()} call would fail |
947 | df0f11a0 | bellard | because of bad page alignment. |
948 | df0f11a0 | bellard | |
949 | 386405f7 | bellard | @section Linux signals |
950 | 386405f7 | bellard | |
951 | 386405f7 | bellard | Normal and real-time signals are queued along with their information |
952 | 386405f7 | bellard | (@code{siginfo_t}) as it is done in the Linux kernel. Then an interrupt |
953 | 386405f7 | bellard | request is done to the virtual CPU. When it is interrupted, one queued |
954 | 386405f7 | bellard | signal is handled by generating a stack frame in the virtual CPU as the |
955 | 386405f7 | bellard | Linux kernel does. The @code{sigreturn()} system call is emulated to return |
956 | 386405f7 | bellard | from the virtual signal handler. |
957 | 386405f7 | bellard | |
958 | 386405f7 | bellard | Some signals (such as SIGALRM) directly come from the host. Other |
959 | 386405f7 | bellard | signals are synthetized from the virtual CPU exceptions such as SIGFPE |
960 | 386405f7 | bellard | when a division by zero is done (see @code{main.c:cpu_loop()}). |
961 | 386405f7 | bellard | |
962 | 386405f7 | bellard | The blocked signal mask is still handled by the host Linux kernel so |
963 | 386405f7 | bellard | that most signal system calls can be redirected directly to the host |
964 | 386405f7 | bellard | Linux kernel. Only the @code{sigaction()} and @code{sigreturn()} system |
965 | 386405f7 | bellard | calls need to be fully emulated (see @file{signal.c}). |
966 | 386405f7 | bellard | |
967 | 386405f7 | bellard | @section clone() system call and threads |
968 | 386405f7 | bellard | |
969 | 386405f7 | bellard | The Linux clone() system call is usually used to create a thread. QEMU |
970 | 386405f7 | bellard | uses the host clone() system call so that real host threads are created |
971 | 386405f7 | bellard | for each emulated thread. One virtual CPU instance is created for each |
972 | 386405f7 | bellard | thread. |
973 | 386405f7 | bellard | |
974 | 386405f7 | bellard | The virtual x86 CPU atomic operations are emulated with a global lock so |
975 | 386405f7 | bellard | that their semantic is preserved. |
976 | 386405f7 | bellard | |
977 | df0f11a0 | bellard | Note that currently there are still some locking issues in QEMU. In |
978 | df0f11a0 | bellard | particular, the translated cache flush is not protected yet against |
979 | df0f11a0 | bellard | reentrancy. |
980 | df0f11a0 | bellard | |
981 | 1eb87257 | bellard | @section Self-virtualization |
982 | 1eb87257 | bellard | |
983 | 4690764b | bellard | QEMU was conceived so that ultimately it can emulate itself. Although |
984 | 1eb87257 | bellard | it is not very useful, it is an important test to show the power of the |
985 | 1eb87257 | bellard | emulator. |
986 | 1eb87257 | bellard | |
987 | 1eb87257 | bellard | Achieving self-virtualization is not easy because there may be address |
988 | 6cd9f35b | bellard | space conflicts. QEMU solves this problem by being an executable ELF |
989 | 6cd9f35b | bellard | shared object as the ld-linux.so ELF interpreter. That way, it can be |
990 | 6cd9f35b | bellard | relocated at load time. |
991 | 1eb87257 | bellard | |
992 | 1eb20527 | bellard | @section MMU emulation |
993 | 1eb20527 | bellard | |
994 | 1eb20527 | bellard | For system emulation, QEMU uses the mmap() system call to emulate the |
995 | 1eb20527 | bellard | target CPU MMU. It works as long the emulated OS does not use an area |
996 | 1eb20527 | bellard | reserved by the host OS (such as the area above 0xc0000000 on x86 |
997 | 1eb20527 | bellard | Linux). |
998 | 1eb20527 | bellard | |
999 | 1eb20527 | bellard | It is planned to add a slower but more precise MMU emulation |
1000 | 1eb20527 | bellard | with a software MMU. |
1001 | 1eb20527 | bellard | |
1002 | 386405f7 | bellard | @section Bibliography |
1003 | 386405f7 | bellard | |
1004 | 386405f7 | bellard | @table @asis |
1005 | 386405f7 | bellard | |
1006 | 386405f7 | bellard | @item [1] |
1007 | 386405f7 | bellard | @url{http://citeseer.nj.nec.com/piumarta98optimizing.html}, Optimizing |
1008 | 386405f7 | bellard | direct threaded code by selective inlining (1998) by Ian Piumarta, Fabio |
1009 | 386405f7 | bellard | Riccardi. |
1010 | 386405f7 | bellard | |
1011 | 386405f7 | bellard | @item [2] |
1012 | 386405f7 | bellard | @url{http://developer.kde.org/~sewardj/}, Valgrind, an open-source |
1013 | 386405f7 | bellard | memory debugger for x86-GNU/Linux, by Julian Seward. |
1014 | 386405f7 | bellard | |
1015 | 386405f7 | bellard | @item [3] |
1016 | 386405f7 | bellard | @url{http://bochs.sourceforge.net/}, the Bochs IA-32 Emulator Project, |
1017 | 386405f7 | bellard | by Kevin Lawton et al. |
1018 | 386405f7 | bellard | |
1019 | 386405f7 | bellard | @item [4] |
1020 | 386405f7 | bellard | @url{http://www.cs.rose-hulman.edu/~donaldlf/em86/index.html}, the EM86 |
1021 | 386405f7 | bellard | x86 emulator on Alpha-Linux. |
1022 | 386405f7 | bellard | |
1023 | 386405f7 | bellard | @item [5] |
1024 | 386405f7 | bellard | @url{http://www.usenix.org/publications/library/proceedings/usenix-nt97/full_papers/chernoff/chernoff.pdf}, |
1025 | 386405f7 | bellard | DIGITAL FX!32: Running 32-Bit x86 Applications on Alpha NT, by Anton |
1026 | 386405f7 | bellard | Chernoff and Ray Hookway. |
1027 | 386405f7 | bellard | |
1028 | fd429f2f | bellard | @item [6] |
1029 | fd429f2f | bellard | @url{http://www.willows.com/}, Windows API library emulation from |
1030 | fd429f2f | bellard | Willows Software. |
1031 | fd429f2f | bellard | |
1032 | 1eb20527 | bellard | @item [7] |
1033 | 1eb20527 | bellard | @url{http://user-mode-linux.sourceforge.net/}, |
1034 | 1eb20527 | bellard | The User-mode Linux Kernel. |
1035 | 1eb20527 | bellard | |
1036 | 1eb20527 | bellard | @item [8] |
1037 | 1eb20527 | bellard | @url{http://www.plex86.org/}, |
1038 | 1eb20527 | bellard | The new Plex86 project. |
1039 | 1eb20527 | bellard | |
1040 | 386405f7 | bellard | @end table |
1041 | 386405f7 | bellard | |
1042 | 386405f7 | bellard | @chapter Regression Tests |
1043 | 386405f7 | bellard | |
1044 | 322d0c66 | bellard | In the directory @file{tests/}, various interesting testing programs |
1045 | 386405f7 | bellard | are available. There are used for regression testing. |
1046 | 386405f7 | bellard | |
1047 | 386405f7 | bellard | @section @file{test-i386} |
1048 | 386405f7 | bellard | |
1049 | 386405f7 | bellard | This program executes most of the 16 bit and 32 bit x86 instructions and |
1050 | 386405f7 | bellard | generates a text output. It can be compared with the output obtained with |
1051 | 386405f7 | bellard | a real CPU or another emulator. The target @code{make test} runs this |
1052 | 386405f7 | bellard | program and a @code{diff} on the generated output. |
1053 | 386405f7 | bellard | |
1054 | 386405f7 | bellard | The Linux system call @code{modify_ldt()} is used to create x86 selectors |
1055 | 386405f7 | bellard | to test some 16 bit addressing and 32 bit with segmentation cases. |
1056 | 386405f7 | bellard | |
1057 | df0f11a0 | bellard | The Linux system call @code{vm86()} is used to test vm86 emulation. |
1058 | 386405f7 | bellard | |
1059 | df0f11a0 | bellard | Various exceptions are raised to test most of the x86 user space |
1060 | df0f11a0 | bellard | exception reporting. |
1061 | 386405f7 | bellard | |
1062 | 285dc330 | bellard | @section @file{linux-test} |
1063 | 285dc330 | bellard | |
1064 | 285dc330 | bellard | This program tests various Linux system calls. It is used to verify |
1065 | 285dc330 | bellard | that the system call parameters are correctly converted between target |
1066 | 285dc330 | bellard | and host CPUs. |
1067 | 285dc330 | bellard | |
1068 | 285dc330 | bellard | @section @file{hello-i386} |
1069 | 285dc330 | bellard | |
1070 | 285dc330 | bellard | Very simple statically linked x86 program, just to test QEMU during a |
1071 | 285dc330 | bellard | port to a new host CPU. |
1072 | 285dc330 | bellard | |
1073 | 285dc330 | bellard | @section @file{hello-arm} |
1074 | 285dc330 | bellard | |
1075 | 285dc330 | bellard | Very simple statically linked ARM program, just to test QEMU during a |
1076 | 285dc330 | bellard | port to a new host CPU. |
1077 | 285dc330 | bellard | |
1078 | 386405f7 | bellard | @section @file{sha1} |
1079 | 386405f7 | bellard | |
1080 | 386405f7 | bellard | It is a simple benchmark. Care must be taken to interpret the results |
1081 | 386405f7 | bellard | because it mostly tests the ability of the virtual CPU to optimize the |
1082 | 386405f7 | bellard | @code{rol} x86 instruction and the condition code computations. |