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\input texinfo @c -*- texinfo -*- |
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@iftex |
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@settitle QEMU CPU Emulator Reference Documentation
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@settitle QEMU CPU Emulator User Documentation
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@titlepage |
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@sp 7 |
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@center @titlefont{QEMU CPU Emulator Reference Documentation}
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@center @titlefont{QEMU CPU Emulator User Documentation}
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@sp 3 |
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@end titlepage |
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@end iftex |
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@section Features |
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QEMU is a FAST! processor emulator. By using dynamic translation it |
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achieves a reasonnable speed while being easy to port on new host |
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CPUs. |
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QEMU is a FAST! processor emulator using dynamic translation to |
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achieve good emulation speed. |
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QEMU has two operating modes: |
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@itemize @minus |
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@item |
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User mode emulation. In this mode, QEMU can launch Linux processes |
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compiled for one CPU on another CPU. Linux system calls are converted |
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because of endianness and 32/64 bit mismatches. The Wine Windows API |
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emulator (@url{http://www.winehq.org}) and the DOSEMU DOS emulator |
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(@url{http://www.dosemu.org}) are the main targets for QEMU. |
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Full system emulation. In this mode, QEMU emulates a full system (for |
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example a PC), including a processor and various peripherials. It can |
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be used to launch different Operating Systems without rebooting the |
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PC or to debug system code. |
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@item |
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Full system emulation. In this mode, QEMU emulates a full |
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system, including a processor and various peripherials. Currently, it |
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is only used to launch an x86 Linux kernel on an x86 Linux system. It |
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enables easier testing and debugging of system code. It can also be |
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used to provide virtual hosting of several virtual PCs on a single |
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server. |
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User mode emulation (Linux host only). In this mode, QEMU can launch |
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Linux processes compiled for one CPU on another CPU. It can be used to |
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launch the Wine Windows API emulator (@url{http://www.winehq.org}) or |
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to ease cross-compilation and cross-debugging. |
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@end itemize |
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As QEMU requires no host kernel patches to run, it is very safe and
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As QEMU requires no host kernel driver to run, it is very safe and
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easy to use. |
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QEMU generic features: |
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For system emulation, only the x86 PC emulator is currently |
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usable. The PowerPC system emulator is being developped. |
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@itemize |
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@item User space only or full system emulation. |
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@item Using dynamic translation to native code for reasonnable speed. |
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@item Working on x86 and PowerPC hosts. Being tested on ARM, Sparc32, Alpha and S390. |
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@item Self-modifying code support. |
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@item Precise exceptions support. |
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@item The virtual CPU is a library (@code{libqemu}) which can be used |
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in other projects. |
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@end itemize |
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QEMU user mode emulation features: |
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@itemize |
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@item Generic Linux system call converter, including most ioctls. |
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@item clone() emulation using native CPU clone() to use Linux scheduler for threads. |
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@item Accurate signal handling by remapping host signals to target signals. |
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@end itemize |
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@end itemize |
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QEMU full system emulation features: |
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@itemize |
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@item QEMU can either use a full software MMU for maximum portability or use the host system call mmap() to simulate the target MMU. |
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@end itemize |
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@section x86 emulation |
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QEMU x86 target features: |
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@itemize |
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@item The virtual x86 CPU supports 16 bit and 32 bit addressing with segmentation. |
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LDT/GDT and IDT are emulated. VM86 mode is also supported to run DOSEMU. |
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@item Support of host page sizes bigger than 4KB in user mode emulation. |
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@item QEMU can emulate itself on x86. |
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@item An extensive Linux x86 CPU test program is included @file{tests/test-i386}. |
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It can be used to test other x86 virtual CPUs. |
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@end itemize |
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Current QEMU limitations: |
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@itemize |
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@item No SSE/MMX support (yet). |
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@item No x86-64 support. |
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@item IPC syscalls are missing. |
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@item The x86 segment limits and access rights are not tested at every |
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memory access. |
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@item On non x86 host CPUs, @code{double}s are used instead of the non standard |
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10 byte @code{long double}s of x86 for floating point emulation to get |
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maximum performances. |
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@item Some priviledged instructions or behaviors are missing, especially for segment protection testing (yet). |
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@end itemize |
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@section ARM emulation |
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@itemize |
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@item ARM emulation can currently launch small programs while using the |
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generic dynamic code generation architecture of QEMU. |
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@item No FPU support (yet). |
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@item No automatic regression testing (yet). |
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@end itemize |
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@section SPARC emulation |
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The SPARC emulation is currently in development. |
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For user emulation, x86, PowerPC, ARM, and SPARC CPUs are supported. |
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@chapter Installation |
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@section Linux |
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If you want to compile QEMU, please read the @file{README} which gives |
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the related information. Otherwise just download the binary |
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distribution (@file{qemu-XXX-i386.tar.gz}) and untar it as root in |
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tar zxvf /tmp/qemu-XXX-i386.tar.gz |
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@end example |
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@chapter QEMU User space emulator invocation |
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@section Quick Start |
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In order to launch a Linux process, QEMU needs the process executable |
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itself and all the target (x86) dynamic libraries used by it. |
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@section Windows |
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w |
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@itemize |
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@item Install the current versions of MSYS and MinGW from |
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@url{http://www.mingw.org/}. You can find detailed installation |
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instructions in the download section and the FAQ. |
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@item Download |
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the MinGW development library of SDL 1.2.x |
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(@file{SDL-devel-1.2.x-mingw32.tar.gz}) from |
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@url{http://www.libsdl.org}. Unpack it in a temporary place, and |
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unpack the archive @file{i386-mingw32msvc.tar.gz} in the MinGW tool |
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directory. Edit the @file{sdl-config} script so that it gives the |
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correct SDL directory when invoked. |
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@item Extract the current version of QEMU. |
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@item Start the MSYS shell (file @file{msys.bat}). |
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@item On x86, you can just try to launch any process by using the native |
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libraries: |
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@example |
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qemu-i386 -L / /bin/ls |
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@end example |
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@code{-L /} tells that the x86 dynamic linker must be searched with a |
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@file{/} prefix. |
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@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): |
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@example |
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qemu-i386 -L / qemu-i386 -L / /bin/ls |
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@end example |
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@item On non x86 CPUs, you need first to download at least an x86 glibc |
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(@file{qemu-runtime-i386-XXX-.tar.gz} on the QEMU web page). Ensure that |
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@code{LD_LIBRARY_PATH} is not set: |
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@example |
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unset LD_LIBRARY_PATH |
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@end example |
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@item Change to the QEMU directory. Launch @file{./configure} and |
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@file{make}. If you have problems using SDL, verify that |
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@file{sdl-config} can be launched from the MSYS command line. |
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Then you can launch the precompiled @file{ls} x86 executable: |
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@example |
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qemu-i386 tests/i386/ls |
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@end example |
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You can look at @file{qemu-binfmt-conf.sh} so that |
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QEMU is automatically launched by the Linux kernel when you try to |
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launch x86 executables. It requires the @code{binfmt_misc} module in the |
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Linux kernel. |
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@item The x86 version of QEMU is also included. You can try weird things such as: |
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@example |
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qemu-i386 /usr/local/qemu-i386/bin/qemu-i386 /usr/local/qemu-i386/bin/ls-i386 |
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@end example |
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@item You can install QEMU in @file{Program Files/Qemu} by typing |
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@file{make install}. Don't forget to copy @file{SDL.dll} in |
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@file{Program Files/Qemu}. |
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@end itemize |
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@section Wine launch
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@section Cross compilation for Windows with Linux
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@itemize |
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@item |
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Install the MinGW cross compilation tools available at |
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@url{http://www.mingw.org/}. |
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@item Ensure that you have a working QEMU with the x86 glibc |
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distribution (see previous section). In order to verify it, you must be |
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able to do: |
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@item |
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Install the Win32 version of SDL (@url{http://www.libsdl.org}) by |
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unpacking @file{i386-mingw32msvc.tar.gz}. Set up the PATH environment |
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variable so that @file{i386-mingw32msvc-sdl-config} can be launched by |
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the QEMU configuration script. |
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@item |
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Configure QEMU for Windows cross compilation: |
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@example |
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qemu-i386 /usr/local/qemu-i386/bin/ls-i386
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./configure --enable-mingw32
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@end example |
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If necessary, you can change the cross-prefix according to the prefix |
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choosen for the MinGW tools with --cross-prefix. You can also use |
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--prefix to set the Win32 install path. |
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@item Download the binary x86 Wine install |
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(@file{qemu-XXX-i386-wine.tar.gz} on the QEMU web page). |
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@item Configure Wine on your account. Look at the provided script |
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@file{/usr/local/qemu-i386/bin/wine-conf.sh}. Your previous |
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@code{$@{HOME@}/.wine} directory is saved to @code{$@{HOME@}/.wine.org}. |
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@item Then you can try the example @file{putty.exe}: |
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@example |
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qemu-i386 /usr/local/qemu-i386/wine/bin/wine /usr/local/qemu-i386/wine/c/Program\ Files/putty.exe |
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@end example |
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@item You can install QEMU in the installation directory by typing |
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@file{make install}. Don't forget to copy @file{SDL.dll} in the |
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installation directory. |
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@end itemize |
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@section Command line options |
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Note: Currently, Wine does not seem able to launch |
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QEMU for Win32. |
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@example |
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usage: qemu-i386 [-h] [-d] [-L path] [-s size] program [arguments...] |
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@end example |
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@section Mac OS X |
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@table @option |
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@item -h |
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Print the help |
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@item -L path |
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Set the x86 elf interpreter prefix (default=/usr/local/qemu-i386) |
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@item -s size |
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Set the x86 stack size in bytes (default=524288) |
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@end table |
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Debug options: |
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@table @option |
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@item -d |
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Activate log (logfile=/tmp/qemu.log) |
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@item -p pagesize |
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Act as if the host page size was 'pagesize' bytes |
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@end table |
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Mac OS X is currently not supported. |
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@chapter QEMU System emulator invocation |
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@c man begin DESCRIPTION |
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The QEMU System emulator simulates a complete PC. It can either boot |
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directly a Linux kernel (without any BIOS or boot loader) or boot like a |
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real PC with the included BIOS. |
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The QEMU System emulator simulates a complete PC. |
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In order to meet specific user needs, two versions of QEMU are |
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available: |
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PS/2 mouse and keyboard |
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@item |
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2 IDE interfaces with hard disk and CD-ROM support |
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@item |
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Floppy disk |
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@item |
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NE2000 network adapter (port=0x300, irq=9)
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up to 6 NE2000 network adapters
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@item |
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Serial port |
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@item |
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Soundblaster 16 card |
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@item |
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PIC (interrupt controler) |
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@item |
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PIT (timers) |
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@item |
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CMOS memory |
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@end itemize |
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@c man end |
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Linux should boot and give you a prompt. |
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@section Direct Linux Boot and Network emulation |
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This section explains how to launch a Linux kernel inside QEMU without |
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having to make a full bootable image. It is very useful for fast Linux |
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kernel testing. The QEMU network configuration is also explained. |
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@enumerate |
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@item |
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Download the archive @file{linux-test-xxx.tar.gz} containing a Linux |
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kernel and a disk image. |
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@item Optional: If you want network support (for example to launch X11 examples), you |
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must copy the script @file{qemu-ifup} in @file{/etc} and configure |
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properly @code{sudo} so that the command @code{ifconfig} contained in |
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@file{qemu-ifup} can be executed as root. You must verify that your host |
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kernel supports the TUN/TAP network interfaces: the device |
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@file{/dev/net/tun} must be present. |
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When network is enabled, there is a virtual network connection between |
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the host kernel and the emulated kernel. The emulated kernel is seen |
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from the host kernel at IP address 172.20.0.2 and the host kernel is |
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seen from the emulated kernel at IP address 172.20.0.1. |
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@item Launch @code{qemu.sh}. You should have the following output: |
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@example |
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> ./qemu.sh |
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Connected to host network interface: tun0 |
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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 |
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BIOS-provided physical RAM map: |
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BIOS-e801: 0000000000000000 - 000000000009f000 (usable) |
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BIOS-e801: 0000000000100000 - 0000000002000000 (usable) |
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32MB LOWMEM available. |
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On node 0 totalpages: 8192 |
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zone(0): 4096 pages. |
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zone(1): 4096 pages. |
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zone(2): 0 pages. |
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Kernel command line: root=/dev/hda sb=0x220,5,1,5 ide2=noprobe ide3=noprobe ide4=noprobe ide5=noprobe console=ttyS0 |
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ide_setup: ide2=noprobe |
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ide_setup: ide3=noprobe |
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ide_setup: ide4=noprobe |
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ide_setup: ide5=noprobe |
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Initializing CPU#0 |
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Detected 2399.621 MHz processor. |
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Console: colour EGA 80x25 |
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Calibrating delay loop... 4744.80 BogoMIPS |
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Memory: 28872k/32768k available (1210k kernel code, 3508k reserved, 266k data, 64k init, 0k highmem) |
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Dentry cache hash table entries: 4096 (order: 3, 32768 bytes) |
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Inode cache hash table entries: 2048 (order: 2, 16384 bytes) |
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Mount cache hash table entries: 512 (order: 0, 4096 bytes) |
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Buffer-cache hash table entries: 1024 (order: 0, 4096 bytes) |
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Page-cache hash table entries: 8192 (order: 3, 32768 bytes) |
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CPU: Intel Pentium Pro stepping 03 |
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Checking 'hlt' instruction... OK. |
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POSIX conformance testing by UNIFIX |
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Linux NET4.0 for Linux 2.4 |
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Based upon Swansea University Computer Society NET3.039 |
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Initializing RT netlink socket |
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apm: BIOS not found. |
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Starting kswapd |
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Journalled Block Device driver loaded |
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Detected PS/2 Mouse Port. |
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pty: 256 Unix98 ptys configured |
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Serial driver version 5.05c (2001-07-08) with no serial options enabled |
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ttyS00 at 0x03f8 (irq = 4) is a 16450 |
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ne.c:v1.10 9/23/94 Donald Becker (becker@scyld.com) |
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Last modified Nov 1, 2000 by Paul Gortmaker |
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NE*000 ethercard probe at 0x300: 52 54 00 12 34 56 |
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eth0: NE2000 found at 0x300, using IRQ 9. |
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RAMDISK driver initialized: 16 RAM disks of 4096K size 1024 blocksize |
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Uniform Multi-Platform E-IDE driver Revision: 7.00beta4-2.4 |
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ide: Assuming 50MHz system bus speed for PIO modes; override with idebus=xx |
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hda: QEMU HARDDISK, ATA DISK drive |
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ide0 at 0x1f0-0x1f7,0x3f6 on irq 14 |
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hda: attached ide-disk driver. |
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hda: 20480 sectors (10 MB) w/256KiB Cache, CHS=20/16/63 |
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Partition check: |
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hda: |
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Soundblaster audio driver Copyright (C) by Hannu Savolainen 1993-1996 |
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NET4: Linux TCP/IP 1.0 for NET4.0 |
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IP Protocols: ICMP, UDP, TCP, IGMP |
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IP: routing cache hash table of 512 buckets, 4Kbytes |
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TCP: Hash tables configured (established 2048 bind 4096) |
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NET4: Unix domain sockets 1.0/SMP for Linux NET4.0. |
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EXT2-fs warning: mounting unchecked fs, running e2fsck is recommended |
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VFS: Mounted root (ext2 filesystem). |
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Freeing unused kernel memory: 64k freed |
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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 |
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QEMU Linux test distribution (based on Redhat 9) |
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|
403 |
Type 'exit' to halt the system |
|
404 |
|
|
405 |
sh-2.05b# |
|
406 |
@end example |
|
407 |
|
|
408 |
@item |
|
409 |
Then you can play with the kernel inside the virtual serial console. You |
|
410 |
can launch @code{ls} for example. Type @key{Ctrl-a h} to have an help |
|
411 |
about the keys you can type inside the virtual serial console. In |
|
412 |
particular, use @key{Ctrl-a x} to exit QEMU and use @key{Ctrl-a b} as |
|
413 |
the Magic SysRq key. |
|
414 |
|
|
415 |
@item |
|
416 |
If the network is enabled, launch the script @file{/etc/linuxrc} in the |
|
417 |
emulator (don't forget the leading dot): |
|
418 |
@example |
|
419 |
. /etc/linuxrc |
|
420 |
@end example |
|
421 |
|
|
422 |
Then enable X11 connections on your PC from the emulated Linux: |
|
423 |
@example |
|
424 |
xhost +172.20.0.2 |
|
425 |
@end example |
|
426 |
|
|
427 |
You can now launch @file{xterm} or @file{xlogo} and verify that you have |
|
428 |
a real Virtual Linux system ! |
|
429 |
|
|
430 |
@end enumerate |
|
431 |
|
|
432 |
NOTES: |
|
433 |
@enumerate |
|
434 |
@item |
|
435 |
A 2.5.74 kernel is also included in the archive. Just |
|
436 |
replace the bzImage in qemu.sh to try it. |
|
437 |
|
|
438 |
@item |
|
439 |
qemu creates a temporary file in @var{$QEMU_TMPDIR} (@file{/tmp} is the |
|
440 |
default) containing all the simulated PC memory. If possible, try to use |
|
441 |
a temporary directory using the tmpfs filesystem to avoid too many |
|
442 |
unnecessary disk accesses. |
|
443 |
|
|
444 |
@item |
|
445 |
In order to exit cleanly from qemu, you can do a @emph{shutdown} inside |
|
446 |
qemu. qemu will automatically exit when the Linux shutdown is done. |
|
447 |
|
|
448 |
@item |
|
449 |
You can boot slightly faster by disabling the probe of non present IDE |
|
450 |
interfaces. To do so, add the following options on the kernel command |
|
451 |
line: |
|
452 |
@example |
|
453 |
ide1=noprobe ide2=noprobe ide3=noprobe ide4=noprobe ide5=noprobe |
|
454 |
@end example |
|
455 |
|
|
456 |
@item |
|
457 |
The example disk image is a modified version of the one made by Kevin |
|
458 |
Lawton for the plex86 Project (@url{www.plex86.org}). |
|
459 |
|
|
460 |
@end enumerate |
|
461 |
|
|
462 | 181 |
@section Invocation |
463 | 182 |
|
464 | 183 |
@example |
... | ... | |
486 | 205 |
Use @var{file} as CD-ROM image (you cannot use @option{-hdc} and and |
487 | 206 |
@option{-cdrom} at the same time). |
488 | 207 |
|
489 |
@item -boot [a|b|c|d]
|
|
490 |
Boot on floppy (a, b), hard disk (c) or CD-ROM (d). Hard disk boot is
|
|
208 |
@item -boot [a|c|d] |
|
209 |
Boot on floppy (a), hard disk (c) or CD-ROM (d). Hard disk boot is |
|
491 | 210 |
the default. |
492 | 211 |
|
493 | 212 |
@item -snapshot |
... | ... | |
498 | 217 |
@item -m megs |
499 | 218 |
Set virtual RAM size to @var{megs} megabytes. |
500 | 219 |
|
501 |
@item -n script |
|
502 |
Set network init script [default=/etc/qemu-ifup]. This script is |
|
503 |
launched to configure the host network interface (usually tun0) |
|
504 |
corresponding to the virtual NE2000 card. |
|
505 |
|
|
506 | 220 |
@item -initrd file |
507 | 221 |
Use @var{file} as initial ram disk. |
508 | 222 |
|
509 |
@item -tun-fd fd |
|
510 |
Assumes @var{fd} talks to tap/tun and use it. Read |
|
511 |
@url{http://bellard.org/qemu/tetrinet.html} to have an example of its |
|
512 |
use. |
|
513 |
|
|
514 | 223 |
@item -nographic |
515 | 224 |
|
516 | 225 |
Normally, QEMU uses SDL to display the VGA output. With this option, |
... | ... | |
521 | 230 |
|
522 | 231 |
@end table |
523 | 232 |
|
524 |
Linux boot specific (does not require a full PC boot with a BIOS): |
|
233 |
Network options: |
|
234 |
|
|
235 |
@table @option |
|
236 |
|
|
237 |
@item -n script |
|
238 |
Set network init script [default=/etc/qemu-ifup]. This script is |
|
239 |
launched to configure the host network interface (usually tun0) |
|
240 |
corresponding to the virtual NE2000 card. |
|
241 |
|
|
242 |
@item nics n |
|
243 |
Simulate @var{n} network interfaces (default=1). |
|
244 |
|
|
245 |
@item -macaddr addr |
|
246 |
|
|
247 |
Set the mac address of the first interface (the format is |
|
248 |
aa:bb:cc:dd:ee:ff in hexa). The mac address is incremented for each |
|
249 |
new network interface. |
|
250 |
|
|
251 |
@item -tun-fd fd1,... |
|
252 |
Assumes @var{fd} talks to tap/tun and use it. Read |
|
253 |
@url{http://bellard.org/qemu/tetrinet.html} to have an example of its |
|
254 |
use. |
|
255 |
|
|
256 |
@end table |
|
257 |
|
|
258 |
Linux boot specific. When using this options, you can use a given |
|
259 |
Linux kernel without installing it in the disk image. It can be useful |
|
260 |
for easier testing of various kernels. |
|
261 |
|
|
525 | 262 |
@table @option |
526 | 263 |
|
527 | 264 |
@item -kernel bzImage |
... | ... | |
545 | 282 |
Output log in /tmp/qemu.log |
546 | 283 |
@end table |
547 | 284 |
|
548 |
During emulation, use @key{C-a h} to get terminal commands: |
|
285 |
During emulation, if you are using the serial console, use @key{C-a h} |
|
286 |
to get terminal commands: |
|
549 | 287 |
|
550 | 288 |
@table @key |
551 | 289 |
@item C-a h |
... | ... | |
555 | 293 |
@item C-a s |
556 | 294 |
Save disk data back to file (if -snapshot) |
557 | 295 |
@item C-a b |
558 |
Send break (magic sysrq) |
|
296 |
Send break (magic sysrq in Linux) |
|
297 |
@item C-a c |
|
298 |
Switch between console and monitor |
|
559 | 299 |
@item C-a C-a |
560 | 300 |
Send C-a |
561 | 301 |
@end table |
... | ... | |
566 | 306 |
@setfilename qemu |
567 | 307 |
@settitle QEMU System Emulator |
568 | 308 |
|
569 |
@c man begin SEEALSO |
|
570 |
The HTML documentation of QEMU for more precise information and Linux |
|
571 |
user mode emulator invocation. |
|
572 |
@c man end |
|
309 |
@c man begin SEEALSO |
|
310 |
The HTML documentation of QEMU for more precise information and Linux |
|
311 |
user mode emulator invocation. |
|
312 |
@c man end |
|
313 |
|
|
314 |
@c man begin AUTHOR |
|
315 |
Fabrice Bellard |
|
316 |
@c man end |
|
317 |
|
|
318 |
@end ignore |
|
319 |
|
|
320 |
@end ignore |
|
321 |
|
|
322 |
|
|
323 |
@section QEMU Monitor |
|
324 |
|
|
325 |
The QEMU monitor is used to give complex commands to the QEMU |
|
326 |
emulator. You can use it to: |
|
327 |
|
|
328 |
@itemize @minus |
|
329 |
|
|
330 |
@item |
|
331 |
Remove or insert removable medias images |
|
332 |
(such as CD-ROM or floppies) |
|
333 |
|
|
334 |
@item |
|
335 |
Freeze/unfreeze the Virtual Machine (VM) and save or restore its state |
|
336 |
from a disk file. |
|
337 |
|
|
338 |
@item Inspect the VM state without an external debugger. |
|
339 |
|
|
340 |
@end itemize |
|
341 |
|
|
342 |
@subsection Commands |
|
343 |
|
|
344 |
The following commands are available: |
|
345 |
|
|
346 |
@table @option |
|
347 |
|
|
348 |
@item help or ? [cmd] |
|
349 |
Show the help for all commands or just for command @var{cmd}. |
|
350 |
|
|
351 |
@item commit |
|
352 |
Commit changes to the disk images (if -snapshot is used) |
|
353 |
|
|
354 |
@item info subcommand |
|
355 |
show various information about the system state |
|
356 |
|
|
357 |
@table @option |
|
358 |
@item info network |
|
359 |
show the network state |
|
360 |
@item info block |
|
361 |
show the block devices |
|
362 |
@item info registers |
|
363 |
show the cpu registers |
|
364 |
@item info history |
|
365 |
show the command line history |
|
366 |
@end table |
|
367 |
|
|
368 |
@item q or quit |
|
369 |
Quit the emulator. |
|
370 |
|
|
371 |
@item eject [-f] device |
|
372 |
Eject a removable media (use -f to force it). |
|
373 |
|
|
374 |
@item change device filename |
|
375 |
Change a removable media. |
|
376 |
|
|
377 |
@item screendump filename |
|
378 |
Save screen into PPM image @var{filename}. |
|
379 |
|
|
380 |
@item log item1[,...] |
|
381 |
Activate logging of the specified items to @file{/tmp/qemu.log}. |
|
382 |
|
|
383 |
@item savevm filename |
|
384 |
Save the whole virtual machine state to @var{filename}. |
|
385 |
|
|
386 |
@item loadvm filename |
|
387 |
Restore the whole virtual machine state from @var{filename}. |
|
388 |
|
|
389 |
@item stop |
|
390 |
Stop emulation. |
|
391 |
|
|
392 |
@item c or cont |
|
393 |
Resume emulation. |
|
394 |
|
|
395 |
@item gdbserver [port] |
|
396 |
Start gdbserver session (default port=1234) |
|
397 |
|
|
398 |
@item x/fmt addr |
|
399 |
Virtual memory dump starting at @var{addr}. |
|
400 |
|
|
401 |
@item xp /fmt addr |
|
402 |
Physical memory dump starting at @var{addr}. |
|
403 |
|
|
404 |
@var{fmt} is a format which tells the command how to format the |
|
405 |
data. Its syntax is: @option{/@{count@}@{format@}@{size@}} |
|
406 |
|
|
407 |
@table @var |
|
408 |
@item count |
|
409 |
is the number of items to be dumped. |
|
410 |
|
|
411 |
@item format |
|
412 |
can be x (hexa), d (signed decimal), u (unsigned decimal), o (octal), |
|
413 |
c (char) or i (asm instruction). |
|
414 |
|
|
415 |
@item size |
|
416 |
can be b (8 bits), h (16 bits), w (32 bits) or g (64 bits) |
|
417 |
|
|
418 |
@end table |
|
419 |
|
|
420 |
Examples: |
|
421 |
@itemize |
|
422 |
@item |
|
423 |
Dump 10 instructions at the current instruction pointer: |
|
424 |
@example |
|
425 |
(qemu) x/10i $eip |
|
426 |
0x90107063: ret |
|
427 |
0x90107064: sti |
|
428 |
0x90107065: lea 0x0(%esi,1),%esi |
|
429 |
0x90107069: lea 0x0(%edi,1),%edi |
|
430 |
0x90107070: ret |
|
431 |
0x90107071: jmp 0x90107080 |
|
432 |
0x90107073: nop |
|
433 |
0x90107074: nop |
|
434 |
0x90107075: nop |
|
435 |
0x90107076: nop |
|
436 |
@end example |
|
437 |
|
|
438 |
@item |
|
439 |
Dump 80 16 bit values at the start of the video memory. |
|
440 |
@example |
|
441 |
(qemu) xp/80hx 0xb8000 |
|
442 |
0x000b8000: 0x0b50 0x0b6c 0x0b65 0x0b78 0x0b38 0x0b36 0x0b2f 0x0b42 |
|
443 |
0x000b8010: 0x0b6f 0x0b63 0x0b68 0x0b73 0x0b20 0x0b56 0x0b47 0x0b41 |
|
444 |
0x000b8020: 0x0b42 0x0b69 0x0b6f 0x0b73 0x0b20 0x0b63 0x0b75 0x0b72 |
|
445 |
0x000b8030: 0x0b72 0x0b65 0x0b6e 0x0b74 0x0b2d 0x0b63 0x0b76 0x0b73 |
|
446 |
0x000b8040: 0x0b20 0x0b30 0x0b35 0x0b20 0x0b4e 0x0b6f 0x0b76 0x0b20 |
|
447 |
0x000b8050: 0x0b32 0x0b30 0x0b30 0x0b33 0x0720 0x0720 0x0720 0x0720 |
|
448 |
0x000b8060: 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 |
|
449 |
0x000b8070: 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 |
|
450 |
0x000b8080: 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 |
|
451 |
0x000b8090: 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 |
|
452 |
@end example |
|
453 |
@end itemize |
|
454 |
|
|
455 |
@item p or print/fmt expr |
|
456 |
|
|
457 |
Print expression value. Only the @var{format} part of @var{fmt} is |
|
458 |
used. |
|
573 | 459 |
|
574 |
@c man begin AUTHOR |
|
575 |
Fabrice Bellard |
|
576 |
@c man end |
|
460 |
@end table |
|
577 | 461 |
|
578 |
@end ignore |
|
462 |
@subsection Integer expressions |
|
463 |
|
|
464 |
The monitor understands integers expressions for every integer |
|
465 |
argument. You can use register names to get the value of specifics |
|
466 |
CPU registers by prefixing them with @emph{$}. |
|
579 | 467 |
|
580 |
@end ignore |
|
581 | 468 |
@node disk_images |
582 | 469 |
@section Disk Images |
583 | 470 |
|
... | ... | |
649 | 536 |
the real one. To know it, use the @code{ls -ls} command. |
650 | 537 |
@end enumerate |
651 | 538 |
|
539 |
@section Direct Linux Boot and Network emulation |
|
540 |
|
|
541 |
This section explains how to launch a Linux kernel inside QEMU without |
|
542 |
having to make a full bootable image. It is very useful for fast Linux |
|
543 |
kernel testing. The QEMU network configuration is also explained. |
|
544 |
|
|
545 |
@enumerate |
|
546 |
@item |
|
547 |
Download the archive @file{linux-test-xxx.tar.gz} containing a Linux |
|
548 |
kernel and a disk image. |
|
549 |
|
|
550 |
@item Optional: If you want network support (for example to launch X11 examples), you |
|
551 |
must copy the script @file{qemu-ifup} in @file{/etc} and configure |
|
552 |
properly @code{sudo} so that the command @code{ifconfig} contained in |
|
553 |
@file{qemu-ifup} can be executed as root. You must verify that your host |
|
554 |
kernel supports the TUN/TAP network interfaces: the device |
|
555 |
@file{/dev/net/tun} must be present. |
|
556 |
|
|
557 |
When network is enabled, there is a virtual network connection between |
|
558 |
the host kernel and the emulated kernel. The emulated kernel is seen |
|
559 |
from the host kernel at IP address 172.20.0.2 and the host kernel is |
|
560 |
seen from the emulated kernel at IP address 172.20.0.1. |
|
561 |
|
|
562 |
@item Launch @code{qemu.sh}. You should have the following output: |
|
563 |
|
|
564 |
@example |
|
565 |
> ./qemu.sh |
|
566 |
Connected to host network interface: tun0 |
|
567 |
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 |
|
568 |
BIOS-provided physical RAM map: |
|
569 |
BIOS-e801: 0000000000000000 - 000000000009f000 (usable) |
|
570 |
BIOS-e801: 0000000000100000 - 0000000002000000 (usable) |
|
571 |
32MB LOWMEM available. |
|
572 |
On node 0 totalpages: 8192 |
|
573 |
zone(0): 4096 pages. |
|
574 |
zone(1): 4096 pages. |
|
575 |
zone(2): 0 pages. |
|
576 |
Kernel command line: root=/dev/hda sb=0x220,5,1,5 ide2=noprobe ide3=noprobe ide4=noprobe ide5=noprobe console=ttyS0 |
|
577 |
ide_setup: ide2=noprobe |
|
578 |
ide_setup: ide3=noprobe |
|
579 |
ide_setup: ide4=noprobe |
|
580 |
ide_setup: ide5=noprobe |
|
581 |
Initializing CPU#0 |
|
582 |
Detected 2399.621 MHz processor. |
|
583 |
Console: colour EGA 80x25 |
|
584 |
Calibrating delay loop... 4744.80 BogoMIPS |
|
585 |
Memory: 28872k/32768k available (1210k kernel code, 3508k reserved, 266k data, 64k init, 0k highmem) |
|
586 |
Dentry cache hash table entries: 4096 (order: 3, 32768 bytes) |
|
587 |
Inode cache hash table entries: 2048 (order: 2, 16384 bytes) |
|
588 |
Mount cache hash table entries: 512 (order: 0, 4096 bytes) |
|
589 |
Buffer-cache hash table entries: 1024 (order: 0, 4096 bytes) |
|
590 |
Page-cache hash table entries: 8192 (order: 3, 32768 bytes) |
|
591 |
CPU: Intel Pentium Pro stepping 03 |
|
592 |
Checking 'hlt' instruction... OK. |
|
593 |
POSIX conformance testing by UNIFIX |
|
594 |
Linux NET4.0 for Linux 2.4 |
|
595 |
Based upon Swansea University Computer Society NET3.039 |
|
596 |
Initializing RT netlink socket |
|
597 |
apm: BIOS not found. |
|
598 |
Starting kswapd |
|
599 |
Journalled Block Device driver loaded |
|
600 |
Detected PS/2 Mouse Port. |
|
601 |
pty: 256 Unix98 ptys configured |
|
602 |
Serial driver version 5.05c (2001-07-08) with no serial options enabled |
|
603 |
ttyS00 at 0x03f8 (irq = 4) is a 16450 |
|
604 |
ne.c:v1.10 9/23/94 Donald Becker (becker@scyld.com) |
|
605 |
Last modified Nov 1, 2000 by Paul Gortmaker |
|
606 |
NE*000 ethercard probe at 0x300: 52 54 00 12 34 56 |
|
607 |
eth0: NE2000 found at 0x300, using IRQ 9. |
|
608 |
RAMDISK driver initialized: 16 RAM disks of 4096K size 1024 blocksize |
|
609 |
Uniform Multi-Platform E-IDE driver Revision: 7.00beta4-2.4 |
|
610 |
ide: Assuming 50MHz system bus speed for PIO modes; override with idebus=xx |
|
611 |
hda: QEMU HARDDISK, ATA DISK drive |
|
612 |
ide0 at 0x1f0-0x1f7,0x3f6 on irq 14 |
|
613 |
hda: attached ide-disk driver. |
|
614 |
hda: 20480 sectors (10 MB) w/256KiB Cache, CHS=20/16/63 |
|
615 |
Partition check: |
|
616 |
hda: |
|
617 |
Soundblaster audio driver Copyright (C) by Hannu Savolainen 1993-1996 |
|
618 |
NET4: Linux TCP/IP 1.0 for NET4.0 |
|
619 |
IP Protocols: ICMP, UDP, TCP, IGMP |
|
620 |
IP: routing cache hash table of 512 buckets, 4Kbytes |
|
621 |
TCP: Hash tables configured (established 2048 bind 4096) |
|
622 |
NET4: Unix domain sockets 1.0/SMP for Linux NET4.0. |
|
623 |
EXT2-fs warning: mounting unchecked fs, running e2fsck is recommended |
|
624 |
VFS: Mounted root (ext2 filesystem). |
|
625 |
Freeing unused kernel memory: 64k freed |
|
626 |
|
|
627 |
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 |
|
628 |
|
|
629 |
QEMU Linux test distribution (based on Redhat 9) |
|
630 |
|
|
631 |
Type 'exit' to halt the system |
|
632 |
|
|
633 |
sh-2.05b# |
|
634 |
@end example |
|
635 |
|
|
636 |
@item |
|
637 |
Then you can play with the kernel inside the virtual serial console. You |
|
638 |
can launch @code{ls} for example. Type @key{Ctrl-a h} to have an help |
|
639 |
about the keys you can type inside the virtual serial console. In |
|
640 |
particular, use @key{Ctrl-a x} to exit QEMU and use @key{Ctrl-a b} as |
|
641 |
the Magic SysRq key. |
|
642 |
|
|
643 |
@item |
|
644 |
If the network is enabled, launch the script @file{/etc/linuxrc} in the |
|
645 |
emulator (don't forget the leading dot): |
|
646 |
@example |
|
647 |
. /etc/linuxrc |
|
648 |
@end example |
|
649 |
|
|
650 |
Then enable X11 connections on your PC from the emulated Linux: |
|
651 |
@example |
|
652 |
xhost +172.20.0.2 |
|
653 |
@end example |
|
654 |
|
|
655 |
You can now launch @file{xterm} or @file{xlogo} and verify that you have |
|
656 |
a real Virtual Linux system ! |
|
657 |
|
|
658 |
@end enumerate |
|
659 |
|
|
660 |
NOTES: |
|
661 |
@enumerate |
|
662 |
@item |
|
663 |
A 2.5.74 kernel is also included in the archive. Just |
|
664 |
replace the bzImage in qemu.sh to try it. |
|
665 |
|
|
666 |
@item |
|
667 |
qemu-fast creates a temporary file in @var{$QEMU_TMPDIR} (@file{/tmp} is the |
|
668 |
default) containing all the simulated PC memory. If possible, try to use |
|
669 |
a temporary directory using the tmpfs filesystem to avoid too many |
|
670 |
unnecessary disk accesses. |
|
671 |
|
|
672 |
@item |
|
673 |
In order to exit cleanly from qemu, you can do a @emph{shutdown} inside |
|
674 |
qemu. qemu will automatically exit when the Linux shutdown is done. |
|
675 |
|
|
676 |
@item |
|
677 |
You can boot slightly faster by disabling the probe of non present IDE |
|
678 |
interfaces. To do so, add the following options on the kernel command |
|
679 |
line: |
|
680 |
@example |
|
681 |
ide1=noprobe ide2=noprobe ide3=noprobe ide4=noprobe ide5=noprobe |
|
682 |
@end example |
|
683 |
|
|
684 |
@item |
|
685 |
The example disk image is a modified version of the one made by Kevin |
|
686 |
Lawton for the plex86 Project (@url{www.plex86.org}). |
|
687 |
|
|
688 |
@end enumerate |
|
689 |
|
|
652 | 690 |
@node linux_compile |
653 | 691 |
@section Linux Kernel Compilation |
654 | 692 |
|
655 | 693 |
You can use any linux kernel with QEMU. However, if you want to use |
656 |
@code{qemu-fast} to get maximum performances, you should make the |
|
657 |
following changes to the Linux kernel (only 2.4.x and 2.5.x were |
|
658 |
tested): |
|
694 |
@code{qemu-fast} to get maximum performances, you must use a modified |
|
695 |
guest kernel. If you are using a 2.6 guest kernel, you can use |
|
696 |
directly the patch @file{linux-2.6-qemu-fast.patch} made by Rusty |
|
697 |
Russel available in the QEMU source archive. Otherwise, you can make the |
|
698 |
following changes @emph{by hand} to the Linux kernel: |
|
659 | 699 |
|
660 | 700 |
@enumerate |
661 | 701 |
@item |
... | ... | |
694 | 734 |
use an SMP kernel with QEMU, it only supports one CPU. |
695 | 735 |
|
696 | 736 |
@item |
697 |
If you are not using a 2.5 kernel as host kernel but if you use a target
|
|
698 |
2.5 kernel, you must also ensure that the 'HZ' define is set to 100
|
|
737 |
If you are not using a 2.6 kernel as host kernel but if you use a target
|
|
738 |
2.6 kernel, you must also ensure that the 'HZ' define is set to 100
|
|
699 | 739 |
(1000 is the default) as QEMU cannot currently emulate timers at |
700 |
frequencies greater than 100 Hz on host Linux systems < 2.5. In
|
|
740 |
frequencies greater than 100 Hz on host Linux systems < 2.6. In
|
|
701 | 741 |
@file{include/asm/param.h}, replace: |
702 | 742 |
|
703 | 743 |
@example |
... | ... | |
762 | 802 |
@code{x/10i $cs*16+*eip} to dump the code at the PC position. |
763 | 803 |
@end enumerate |
764 | 804 |
|
765 |
@chapter QEMU Internals |
|
766 |
|
|
767 |
@section QEMU compared to other emulators |
|
768 |
|
|
769 |
Like bochs [3], QEMU emulates an x86 CPU. But QEMU is much faster than |
|
770 |
bochs as it uses dynamic compilation and because it uses the host MMU to |
|
771 |
simulate the x86 MMU. The downside is that currently the emulation is |
|
772 |
not as accurate as bochs (for example, you cannot currently run Windows |
|
773 |
inside QEMU). |
|
774 |
|
|
775 |
Like Valgrind [2], QEMU does user space emulation and dynamic |
|
776 |
translation. Valgrind is mainly a memory debugger while QEMU has no |
|
777 |
support for it (QEMU could be used to detect out of bound memory |
|
778 |
accesses as Valgrind, but it has no support to track uninitialised data |
|
779 |
as Valgrind does). The Valgrind dynamic translator generates better code |
|
780 |
than QEMU (in particular it does register allocation) but it is closely |
|
781 |
tied to an x86 host and target and has no support for precise exceptions |
|
782 |
and system emulation. |
|
783 |
|
|
784 |
EM86 [4] is the closest project to user space QEMU (and QEMU still uses |
|
785 |
some of its code, in particular the ELF file loader). EM86 was limited |
|
786 |
to an alpha host and used a proprietary and slow interpreter (the |
|
787 |
interpreter part of the FX!32 Digital Win32 code translator [5]). |
|
788 |
|
|
789 |
TWIN [6] is a Windows API emulator like Wine. It is less accurate than |
|
790 |
Wine but includes a protected mode x86 interpreter to launch x86 Windows |
|
791 |
executables. Such an approach as greater potential because most of the |
|
792 |
Windows API is executed natively but it is far more difficult to develop |
|
793 |
because all the data structures and function parameters exchanged |
|
794 |
between the API and the x86 code must be converted. |
|
795 |
|
|
796 |
User mode Linux [7] was the only solution before QEMU to launch a Linux |
|
797 |
kernel as a process while not needing any host kernel patches. However, |
|
798 |
user mode Linux requires heavy kernel patches while QEMU accepts |
|
799 |
unpatched Linux kernels. It would be interesting to compare the |
|
800 |
performance of the two approaches. |
|
801 |
|
|
802 |
The new Plex86 [8] PC virtualizer is done in the same spirit as the QEMU |
|
803 |
system emulator. It requires a patched Linux kernel to work (you cannot |
|
804 |
launch the same kernel on your PC), but the patches are really small. As |
|
805 |
it is a PC virtualizer (no emulation is done except for some priveledged |
|
806 |
instructions), it has the potential of being faster than QEMU. The |
|
807 |
downside is that a complicated (and potentially unsafe) host kernel |
|
808 |
patch is needed. |
|
809 |
|
|
810 |
@section Portable dynamic translation |
|
811 |
|
|
812 |
QEMU is a dynamic translator. When it first encounters a piece of code, |
|
813 |
it converts it to the host instruction set. Usually dynamic translators |
|
814 |
are very complicated and highly CPU dependent. QEMU uses some tricks |
|
815 |
which make it relatively easily portable and simple while achieving good |
|
816 |
performances. |
|
817 |
|
|
818 |
The basic idea is to split every x86 instruction into fewer simpler |
|
819 |
instructions. Each simple instruction is implemented by a piece of C |
|
820 |
code (see @file{op-i386.c}). Then a compile time tool (@file{dyngen}) |
|
821 |
takes the corresponding object file (@file{op-i386.o}) to generate a |
|
822 |
dynamic code generator which concatenates the simple instructions to |
|
823 |
build a function (see @file{op-i386.h:dyngen_code()}). |
|
824 |
|
|
825 |
In essence, the process is similar to [1], but more work is done at |
|
826 |
compile time. |
|
827 |
|
|
828 |
A key idea to get optimal performances is that constant parameters can |
|
829 |
be passed to the simple operations. For that purpose, dummy ELF |
|
830 |
relocations are generated with gcc for each constant parameter. Then, |
|
831 |
the tool (@file{dyngen}) can locate the relocations and generate the |
|
832 |
appriopriate C code to resolve them when building the dynamic code. |
|
833 |
|
|
834 |
That way, QEMU is no more difficult to port than a dynamic linker. |
|
835 |
|
|
836 |
To go even faster, GCC static register variables are used to keep the |
|
837 |
state of the virtual CPU. |
|
838 |
|
|
839 |
@section Register allocation |
|
840 |
|
|
841 |
Since QEMU uses fixed simple instructions, no efficient register |
|
842 |
allocation can be done. However, because RISC CPUs have a lot of |
|
843 |
register, most of the virtual CPU state can be put in registers without |
|
844 |
doing complicated register allocation. |
|
845 |
|
|
846 |
@section Condition code optimisations |
|
847 |
|
|
848 |
Good CPU condition codes emulation (@code{EFLAGS} register on x86) is a |
|
849 |
critical point to get good performances. QEMU uses lazy condition code |
|
850 |
evaluation: instead of computing the condition codes after each x86 |
|
851 |
instruction, it just stores one operand (called @code{CC_SRC}), the |
|
852 |
result (called @code{CC_DST}) and the type of operation (called |
|
853 |
@code{CC_OP}). |
|
854 |
|
|
855 |
@code{CC_OP} is almost never explicitely set in the generated code |
|
856 |
because it is known at translation time. |
|
857 |
|
|
858 |
In order to increase performances, a backward pass is performed on the |
|
859 |
generated simple instructions (see |
|
860 |
@code{translate-i386.c:optimize_flags()}). When it can be proved that |
|
861 |
the condition codes are not needed by the next instructions, no |
|
862 |
condition codes are computed at all. |
|
863 |
|
|
864 |
@section CPU state optimisations |
|
865 |
|
|
866 |
The x86 CPU has many internal states which change the way it evaluates |
|
867 |
instructions. In order to achieve a good speed, the translation phase |
|
868 |
considers that some state information of the virtual x86 CPU cannot |
|
869 |
change in it. For example, if the SS, DS and ES segments have a zero |
|
870 |
base, then the translator does not even generate an addition for the |
|
871 |
segment base. |
|
872 |
|
|
873 |
[The FPU stack pointer register is not handled that way yet]. |
|
874 |
|
|
875 |
@section Translation cache |
|
876 |
|
|
877 |
A 2MByte cache holds the most recently used translations. For |
|
878 |
simplicity, it is completely flushed when it is full. A translation unit |
|
879 |
contains just a single basic block (a block of x86 instructions |
|
880 |
terminated by a jump or by a virtual CPU state change which the |
|
881 |
translator cannot deduce statically). |
|
882 |
|
|
883 |
@section Direct block chaining |
|
884 |
|
|
885 |
After each translated basic block is executed, QEMU uses the simulated |
|
886 |
Program Counter (PC) and other cpu state informations (such as the CS |
|
887 |
segment base value) to find the next basic block. |
|
888 |
|
|
889 |
In order to accelerate the most common cases where the new simulated PC |
|
890 |
is known, QEMU can patch a basic block so that it jumps directly to the |
|
891 |
next one. |
|
892 |
|
|
893 |
The most portable code uses an indirect jump. An indirect jump makes it |
|
894 |
easier to make the jump target modification atomic. On some |
|
895 |
architectures (such as PowerPC), the @code{JUMP} opcode is directly |
|
896 |
patched so that the block chaining has no overhead. |
|
897 |
|
|
898 |
@section Self-modifying code and translated code invalidation |
|
899 |
|
|
900 |
Self-modifying code is a special challenge in x86 emulation because no |
|
901 |
instruction cache invalidation is signaled by the application when code |
|
902 |
is modified. |
|
903 |
|
|
904 |
When translated code is generated for a basic block, the corresponding |
|
905 |
host page is write protected if it is not already read-only (with the |
|
906 |
system call @code{mprotect()}). Then, if a write access is done to the |
|
907 |
page, Linux raises a SEGV signal. QEMU then invalidates all the |
|
908 |
translated code in the page and enables write accesses to the page. |
|
909 |
|
|
910 |
Correct translated code invalidation is done efficiently by maintaining |
|
911 |
a linked list of every translated block contained in a given page. Other |
|
912 |
linked lists are also maintained to undo direct block chaining. |
|
913 |
|
|
914 |
Although the overhead of doing @code{mprotect()} calls is important, |
|
915 |
most MSDOS programs can be emulated at reasonnable speed with QEMU and |
|
916 |
DOSEMU. |
|
917 |
|
|
918 |
Note that QEMU also invalidates pages of translated code when it detects |
|
919 |
that memory mappings are modified with @code{mmap()} or @code{munmap()}. |
|
920 |
|
|
921 |
@section Exception support |
|
922 |
|
|
923 |
longjmp() is used when an exception such as division by zero is |
|
924 |
encountered. |
|
925 |
|
|
926 |
The host SIGSEGV and SIGBUS signal handlers are used to get invalid |
|
927 |
memory accesses. The exact CPU state can be retrieved because all the |
|
928 |
x86 registers are stored in fixed host registers. The simulated program |
|
929 |
counter is found by retranslating the corresponding basic block and by |
|
930 |
looking where the host program counter was at the exception point. |
|
931 |
|
|
932 |
The virtual CPU cannot retrieve the exact @code{EFLAGS} register because |
|
933 |
in some cases it is not computed because of condition code |
|
934 |
optimisations. It is not a big concern because the emulated code can |
|
935 |
still be restarted in any cases. |
|
936 |
|
|
937 |
@section Linux system call translation |
|
938 |
|
|
939 |
QEMU includes a generic system call translator for Linux. It means that |
|
940 |
the parameters of the system calls can be converted to fix the |
|
941 |
endianness and 32/64 bit issues. The IOCTLs are converted with a generic |
|
942 |
type description system (see @file{ioctls.h} and @file{thunk.c}). |
|
805 |
@chapter QEMU User space emulator invocation |
|
943 | 806 |
|
944 |
QEMU supports host CPUs which have pages bigger than 4KB. It records all |
|
945 |
the mappings the process does and try to emulated the @code{mmap()} |
|
946 |
system calls in cases where the host @code{mmap()} call would fail |
|
947 |
because of bad page alignment. |
|
807 |
@section Quick Start |
|
948 | 808 |
|
949 |
@section Linux signals |
|
809 |
In order to launch a Linux process, QEMU needs the process executable |
|
810 |
itself and all the target (x86) dynamic libraries used by it. |
|
950 | 811 |
|
951 |
Normal and real-time signals are queued along with their information |
|
952 |
(@code{siginfo_t}) as it is done in the Linux kernel. Then an interrupt |
|
953 |
request is done to the virtual CPU. When it is interrupted, one queued |
|
954 |
signal is handled by generating a stack frame in the virtual CPU as the |
|
955 |
Linux kernel does. The @code{sigreturn()} system call is emulated to return |
|
956 |
from the virtual signal handler. |
|
812 |
@itemize |
|
957 | 813 |
|
958 |
Some signals (such as SIGALRM) directly come from the host. Other |
|
959 |
signals are synthetized from the virtual CPU exceptions such as SIGFPE |
|
960 |
when a division by zero is done (see @code{main.c:cpu_loop()}). |
|
814 |
@item On x86, you can just try to launch any process by using the native |
|
815 |
libraries: |
|
961 | 816 |
|
962 |
The blocked signal mask is still handled by the host Linux kernel so |
|
963 |
that most signal system calls can be redirected directly to the host |
|
964 |
Linux kernel. Only the @code{sigaction()} and @code{sigreturn()} system |
|
965 |
calls need to be fully emulated (see @file{signal.c}). |
|
817 |
@example |
|
818 |
qemu-i386 -L / /bin/ls |
|
819 |
@end example |
|
966 | 820 |
|
967 |
@section clone() system call and threads |
|
821 |
@code{-L /} tells that the x86 dynamic linker must be searched with a |
|
822 |
@file{/} prefix. |
|
968 | 823 |
|
969 |
The Linux clone() system call is usually used to create a thread. QEMU |
|
970 |
uses the host clone() system call so that real host threads are created |
|
971 |
for each emulated thread. One virtual CPU instance is created for each |
|
972 |
thread. |
|
824 |
@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): |
|
973 | 825 |
|
974 |
The virtual x86 CPU atomic operations are emulated with a global lock so |
|
975 |
that their semantic is preserved. |
|
826 |
@example |
|
827 |
qemu-i386 -L / qemu-i386 -L / /bin/ls |
|
828 |
@end example |
|
976 | 829 |
|
977 |
Note that currently there are still some locking issues in QEMU. In
|
|
978 |
particular, the translated cache flush is not protected yet against
|
|
979 |
reentrancy.
|
|
830 |
@item On non x86 CPUs, you need first to download at least an x86 glibc
|
|
831 |
(@file{qemu-runtime-i386-XXX-.tar.gz} on the QEMU web page). Ensure that
|
|
832 |
@code{LD_LIBRARY_PATH} is not set:
|
|
980 | 833 |
|
981 |
@section Self-virtualization |
|
834 |
@example |
|
835 |
unset LD_LIBRARY_PATH |
|
836 |
@end example |
|
982 | 837 |
|
983 |
QEMU was conceived so that ultimately it can emulate itself. Although |
|
984 |
it is not very useful, it is an important test to show the power of the |
|
985 |
emulator. |
|
838 |
Then you can launch the precompiled @file{ls} x86 executable: |
|
986 | 839 |
|
987 |
Achieving self-virtualization is not easy because there may be address |
|
988 |
space conflicts. QEMU solves this problem by being an executable ELF |
|
989 |
shared object as the ld-linux.so ELF interpreter. That way, it can be |
|
990 |
relocated at load time. |
|
840 |
@example |
|
841 |
qemu-i386 tests/i386/ls |
|
842 |
@end example |
|
843 |
You can look at @file{qemu-binfmt-conf.sh} so that |
|
844 |
QEMU is automatically launched by the Linux kernel when you try to |
|
845 |
launch x86 executables. It requires the @code{binfmt_misc} module in the |
|
846 |
Linux kernel. |
|
991 | 847 |
|
992 |
@section MMU emulation |
|
848 |
@item The x86 version of QEMU is also included. You can try weird things such as: |
|
849 |
@example |
|
850 |
qemu-i386 /usr/local/qemu-i386/bin/qemu-i386 /usr/local/qemu-i386/bin/ls-i386 |
|
851 |
@end example |
|
993 | 852 |
|
994 |
For system emulation, QEMU uses the mmap() system call to emulate the |
|
995 |
target CPU MMU. It works as long the emulated OS does not use an area |
|
996 |
reserved by the host OS (such as the area above 0xc0000000 on x86 |
|
997 |
Linux). |
|
853 |
@end itemize |
|
998 | 854 |
|
999 |
It is planned to add a slower but more precise MMU emulation |
|
1000 |
with a software MMU. |
|
855 |
@section Wine launch |
|
1001 | 856 |
|
1002 |
@section Bibliography
|
|
857 |
@itemize
|
|
1003 | 858 |
|
1004 |
@table @asis |
|
859 |
@item Ensure that you have a working QEMU with the x86 glibc |
|
860 |
distribution (see previous section). In order to verify it, you must be |
|
861 |
able to do: |
|
1005 | 862 |
|
1006 |
@item [1] |
|
1007 |
@url{http://citeseer.nj.nec.com/piumarta98optimizing.html}, Optimizing |
|
1008 |
direct threaded code by selective inlining (1998) by Ian Piumarta, Fabio |
|
1009 |
Riccardi. |
|
863 |
@example |
|
864 |
qemu-i386 /usr/local/qemu-i386/bin/ls-i386 |
|
865 |
@end example |
|
1010 | 866 |
|
1011 |
@item [2] |
|
1012 |
@url{http://developer.kde.org/~sewardj/}, Valgrind, an open-source |
|
1013 |
memory debugger for x86-GNU/Linux, by Julian Seward. |
|
867 |
@item Download the binary x86 Wine install |
|
868 |
(@file{qemu-XXX-i386-wine.tar.gz} on the QEMU web page). |
|
1014 | 869 |
|
1015 |
@item [3]
|
|
1016 |
@url{http://bochs.sourceforge.net/}, the Bochs IA-32 Emulator Project,
|
|
1017 |
by Kevin Lawton et al.
|
|
870 |
@item Configure Wine on your account. Look at the provided script
|
|
871 |
@file{/usr/local/qemu-i386/bin/wine-conf.sh}. Your previous
|
|
872 |
@code{$@{HOME@}/.wine} directory is saved to @code{$@{HOME@}/.wine.org}.
|
|
1018 | 873 |
|
1019 |
@item [4] |
|
1020 |
@url{http://www.cs.rose-hulman.edu/~donaldlf/em86/index.html}, the EM86 |
|
1021 |
x86 emulator on Alpha-Linux. |
|
874 |
@item Then you can try the example @file{putty.exe}: |
|
1022 | 875 |
|
1023 |
@item [5] |
|
1024 |
@url{http://www.usenix.org/publications/library/proceedings/usenix-nt97/full_papers/chernoff/chernoff.pdf}, |
|
1025 |
DIGITAL FX!32: Running 32-Bit x86 Applications on Alpha NT, by Anton |
|
1026 |
Chernoff and Ray Hookway. |
|
876 |
@example |
|
877 |
qemu-i386 /usr/local/qemu-i386/wine/bin/wine /usr/local/qemu-i386/wine/c/Program\ Files/putty.exe |
|
878 |
@end example |
|
1027 | 879 |
|
1028 |
@item [6] |
|
1029 |
@url{http://www.willows.com/}, Windows API library emulation from |
|
1030 |
Willows Software. |
|
880 |
@end itemize |
|
1031 | 881 |
|
1032 |
@item [7] |
|
1033 |
@url{http://user-mode-linux.sourceforge.net/}, |
|
1034 |
The User-mode Linux Kernel. |
|
882 |
@section Command line options |
|
1035 | 883 |
|
1036 |
@item [8]
|
|
1037 |
@url{http://www.plex86.org/},
|
|
1038 |
The new Plex86 project.
|
|
884 |
@example
|
|
885 |
usage: qemu-i386 [-h] [-d] [-L path] [-s size] program [arguments...]
|
|
886 |
@end example
|
|
1039 | 887 |
|
888 |
@table @option |
|
889 |
@item -h |
|
890 |
Print the help |
|
891 |
@item -L path |
|
892 |
Set the x86 elf interpreter prefix (default=/usr/local/qemu-i386) |
|
893 |
@item -s size |
|
894 |
Set the x86 stack size in bytes (default=524288) |
|
1040 | 895 |
@end table |
1041 | 896 |
|
1042 |
@chapter Regression Tests |
|
1043 |
|
|
1044 |
In the directory @file{tests/}, various interesting testing programs |
|
1045 |
are available. There are used for regression testing. |
|
1046 |
|
|
1047 |
@section @file{test-i386} |
|
1048 |
|
|
1049 |
This program executes most of the 16 bit and 32 bit x86 instructions and |
|
1050 |
generates a text output. It can be compared with the output obtained with |
|
1051 |
a real CPU or another emulator. The target @code{make test} runs this |
|
1052 |
program and a @code{diff} on the generated output. |
|
1053 |
|
|
1054 |
The Linux system call @code{modify_ldt()} is used to create x86 selectors |
|
1055 |
to test some 16 bit addressing and 32 bit with segmentation cases. |
|
1056 |
|
|
1057 |
The Linux system call @code{vm86()} is used to test vm86 emulation. |
|
1058 |
|
|
1059 |
Various exceptions are raised to test most of the x86 user space |
|
1060 |
exception reporting. |
|
1061 |
|
|
1062 |
@section @file{linux-test} |
|
1063 |
|
|
1064 |
This program tests various Linux system calls. It is used to verify |
|
1065 |
that the system call parameters are correctly converted between target |
|
1066 |
and host CPUs. |
|
1067 |
|
|
1068 |
@section @file{hello-i386} |
|
1069 |
|
|
1070 |
Very simple statically linked x86 program, just to test QEMU during a |
|
1071 |
port to a new host CPU. |
|
1072 |
|
|
1073 |
@section @file{hello-arm} |
|
1074 |
|
|
1075 |
Very simple statically linked ARM program, just to test QEMU during a |
|
1076 |
port to a new host CPU. |
|
1077 |
|
|
1078 |
@section @file{sha1} |
|
897 |
Debug options: |
|
1079 | 898 |
|
1080 |
It is a simple benchmark. Care must be taken to interpret the results |
|
1081 |
because it mostly tests the ability of the virtual CPU to optimize the |
|
1082 |
@code{rol} x86 instruction and the condition code computations. |
|
899 |
@table @option |
|
900 |
@item -d |
|
901 |
Activate log (logfile=/tmp/qemu.log) |
|
902 |
@item -p pagesize |
|
903 |
Act as if the host page size was 'pagesize' bytes |
|
904 |
@end table |
|
1083 | 905 |
|
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