1 \input texinfo @c -*- texinfo -*-
4 @settitle QEMU CPU Emulator User Documentation
7 @center @titlefont{QEMU CPU Emulator User Documentation}
16 QEMU is a FAST! processor emulator using dynamic translation to
17 achieve good emulation speed.
19 QEMU has two operating modes:
24 Full system emulation. In this mode, QEMU emulates a full system (for
25 example a PC), including a processor and various peripherials. It can
26 be used to launch different Operating Systems without rebooting the
27 PC or to debug system code.
30 User mode emulation (Linux host only). In this mode, QEMU can launch
31 Linux processes compiled for one CPU on another CPU. It can be used to
32 launch the Wine Windows API emulator (@url{http://www.winehq.org}) or
33 to ease cross-compilation and cross-debugging.
37 As QEMU requires no host kernel driver to run, it is very safe and
40 For system emulation, only the x86 PC emulator is currently
41 usable. The PowerPC system emulator is being developped.
43 For user emulation, x86, PowerPC, ARM, and SPARC CPUs are supported.
49 If you want to compile QEMU, please read the @file{README} which gives
50 the related information. Otherwise just download the binary
51 distribution (@file{qemu-XXX-i386.tar.gz}) and untar it as root in
57 tar zxvf /tmp/qemu-XXX-i386.tar.gz
63 @item Install the current versions of MSYS and MinGW from
64 @url{http://www.mingw.org/}. You can find detailed installation
65 instructions in the download section and the FAQ.
68 the MinGW development library of SDL 1.2.x
69 (@file{SDL-devel-1.2.x-mingw32.tar.gz}) from
70 @url{http://www.libsdl.org}. Unpack it in a temporary place, and
71 unpack the archive @file{i386-mingw32msvc.tar.gz} in the MinGW tool
72 directory. Edit the @file{sdl-config} script so that it gives the
73 correct SDL directory when invoked.
75 @item Extract the current version of QEMU.
77 @item Start the MSYS shell (file @file{msys.bat}).
79 @item Change to the QEMU directory. Launch @file{./configure} and
80 @file{make}. If you have problems using SDL, verify that
81 @file{sdl-config} can be launched from the MSYS command line.
83 @item You can install QEMU in @file{Program Files/Qemu} by typing
84 @file{make install}. Don't forget to copy @file{SDL.dll} in
85 @file{Program Files/Qemu}.
89 @section Cross compilation for Windows with Linux
93 Install the MinGW cross compilation tools available at
94 @url{http://www.mingw.org/}.
97 Install the Win32 version of SDL (@url{http://www.libsdl.org}) by
98 unpacking @file{i386-mingw32msvc.tar.gz}. Set up the PATH environment
99 variable so that @file{i386-mingw32msvc-sdl-config} can be launched by
100 the QEMU configuration script.
103 Configure QEMU for Windows cross compilation:
105 ./configure --enable-mingw32
107 If necessary, you can change the cross-prefix according to the prefix
108 choosen for the MinGW tools with --cross-prefix. You can also use
109 --prefix to set the Win32 install path.
111 @item You can install QEMU in the installation directory by typing
112 @file{make install}. Don't forget to copy @file{SDL.dll} in the
113 installation directory.
117 Note: Currently, Wine does not seem able to launch
122 Mac OS X is currently not supported.
124 @chapter QEMU System emulator invocation
126 @section Introduction
128 @c man begin DESCRIPTION
130 The QEMU System emulator simulates a complete PC.
132 In order to meet specific user needs, two versions of QEMU are
138 @code{qemu-fast} uses the host Memory Management Unit (MMU) to simulate
139 the x86 MMU. It is @emph{fast} but has limitations because the whole 4 GB
140 address space cannot be used and some memory mapped peripherials
141 cannot be emulated accurately yet. Therefore, a specific Linux kernel
142 must be used (@xref{linux_compile}).
145 @code{qemu} uses a software MMU. It is about @emph{two times
146 slower} but gives a more accurate emulation.
150 QEMU emulates the following PC peripherials:
154 VGA (hardware level, including all non standard modes)
156 PS/2 mouse and keyboard
158 2 IDE interfaces with hard disk and CD-ROM support
162 up to 6 NE2000 network adapters
173 Download and uncompress the linux image (@file{linux.img}) and type:
179 Linux should boot and give you a prompt.
184 @c man begin SYNOPSIS
185 usage: qemu [options] [disk_image]
190 @var{disk_image} is a raw hard disk image for IDE hard disk 0.
196 Use @var{file} as floppy disk 0/1 image (@xref{disk_images}).
202 Use @var{file} as hard disk 0, 1, 2 or 3 image (@xref{disk_images}).
205 Use @var{file} as CD-ROM image (you cannot use @option{-hdc} and and
206 @option{-cdrom} at the same time).
209 Boot on floppy (a), hard disk (c) or CD-ROM (d). Hard disk boot is
213 Write to temporary files instead of disk image files. In this case,
214 the raw disk image you use is not written back. You can however force
215 the write back by pressing @key{C-a s} (@xref{disk_images}).
218 Set virtual RAM size to @var{megs} megabytes.
221 Use @var{file} as initial ram disk.
225 Normally, QEMU uses SDL to display the VGA output. With this option,
226 you can totally disable graphical output so that QEMU is a simple
227 command line application. The emulated serial port is redirected on
228 the console. Therefore, you can still use QEMU to debug a Linux kernel
229 with a serial console.
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.
243 Simulate @var{n} network interfaces (default=1).
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.
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
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.
264 @item -kernel bzImage
265 Use @var{bzImage} as kernel image.
267 @item -append cmdline
268 Use @var{cmdline} as kernel command line
271 Use @var{file} as initial ram disk.
278 Wait gdb connection to port 1234 (@xref{gdb_usage}).
280 Change gdb connection port.
282 Output log in /tmp/qemu.log
285 During emulation, if you are using the serial console, use @key{C-a h}
286 to get terminal commands:
294 Save disk data back to file (if -snapshot)
296 Send break (magic sysrq in Linux)
298 Switch between console and monitor
307 @settitle QEMU System Emulator
310 The HTML documentation of QEMU for more precise information and Linux
311 user mode emulator invocation.
323 @section QEMU Monitor
325 The QEMU monitor is used to give complex commands to the QEMU
326 emulator. You can use it to:
331 Remove or insert removable medias images
332 (such as CD-ROM or floppies)
335 Freeze/unfreeze the Virtual Machine (VM) and save or restore its state
338 @item Inspect the VM state without an external debugger.
344 The following commands are available:
348 @item help or ? [cmd]
349 Show the help for all commands or just for command @var{cmd}.
352 Commit changes to the disk images (if -snapshot is used)
354 @item info subcommand
355 show various information about the system state
359 show the network state
361 show the block devices
363 show the cpu registers
365 show the command line history
371 @item eject [-f] device
372 Eject a removable media (use -f to force it).
374 @item change device filename
375 Change a removable media.
377 @item screendump filename
378 Save screen into PPM image @var{filename}.
380 @item log item1[,...]
381 Activate logging of the specified items to @file{/tmp/qemu.log}.
383 @item savevm filename
384 Save the whole virtual machine state to @var{filename}.
386 @item loadvm filename
387 Restore the whole virtual machine state from @var{filename}.
395 @item gdbserver [port]
396 Start gdbserver session (default port=1234)
399 Virtual memory dump starting at @var{addr}.
402 Physical memory dump starting at @var{addr}.
404 @var{fmt} is a format which tells the command how to format the
405 data. Its syntax is: @option{/@{count@}@{format@}@{size@}}
409 is the number of items to be dumped.
412 can be x (hexa), d (signed decimal), u (unsigned decimal), o (octal),
413 c (char) or i (asm instruction).
416 can be b (8 bits), h (16 bits), w (32 bits) or g (64 bits)
423 Dump 10 instructions at the current instruction pointer:
428 0x90107065: lea 0x0(%esi,1),%esi
429 0x90107069: lea 0x0(%edi,1),%edi
431 0x90107071: jmp 0x90107080
439 Dump 80 16 bit values at the start of the video memory.
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
455 @item p or print/fmt expr
457 Print expression value. Only the @var{format} part of @var{fmt} is
462 @subsection Integer expressions
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{$}.
471 @subsection Raw disk images
473 The disk images can simply be raw images of the hard disk. You can
474 create them with the command:
476 dd if=/dev/zero of=myimage bs=1024 count=mysize
478 where @var{myimage} is the image filename and @var{mysize} is its size
481 @subsection Snapshot mode
483 If you use the option @option{-snapshot}, all disk images are
484 considered as read only. When sectors in written, they are written in
485 a temporary file created in @file{/tmp}. You can however force the
486 write back to the raw disk images by pressing @key{C-a s}.
488 NOTE: The snapshot mode only works with raw disk images.
490 @subsection Copy On Write disk images
492 QEMU also supports user mode Linux
493 (@url{http://user-mode-linux.sourceforge.net/}) Copy On Write (COW)
494 disk images. The COW disk images are much smaller than normal images
495 as they store only modified sectors. They also permit the use of the
496 same disk image template for many users.
498 To create a COW disk images, use the command:
501 qemu-mkcow -f myrawimage.bin mycowimage.cow
504 @file{myrawimage.bin} is a raw image you want to use as original disk
505 image. It will never be written to.
507 @file{mycowimage.cow} is the COW disk image which is created by
508 @code{qemu-mkcow}. You can use it directly with the @option{-hdx}
509 options. You must not modify the original raw disk image if you use
510 COW images, as COW images only store the modified sectors from the raw
511 disk image. QEMU stores the original raw disk image name and its
512 modified time in the COW disk image so that chances of mistakes are
515 If the raw disk image is not read-only, by pressing @key{C-a s} you
516 can flush the COW disk image back into the raw disk image, as in
519 COW disk images can also be created without a corresponding raw disk
520 image. It is useful to have a big initial virtual disk image without
521 using much disk space. Use:
524 qemu-mkcow mycowimage.cow 1024
527 to create a 1 gigabyte empty COW disk image.
532 COW disk images must be created on file systems supporting
533 @emph{holes} such as ext2 or ext3.
535 Since holes are used, the displayed size of the COW disk image is not
536 the real one. To know it, use the @code{ls -ls} command.
539 @section Direct Linux Boot and Network emulation
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.
547 Download the archive @file{linux-test-xxx.tar.gz} containing a Linux
548 kernel and a disk image.
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.
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.
562 @item Launch @code{qemu.sh}. You should have the following output:
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
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
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
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
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
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
629 QEMU Linux test distribution (based on Redhat 9)
631 Type 'exit' to halt the system
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
644 If the network is enabled, launch the script @file{/etc/linuxrc} in the
645 emulator (don't forget the leading dot):
650 Then enable X11 connections on your PC from the emulated Linux:
655 You can now launch @file{xterm} or @file{xlogo} and verify that you have
656 a real Virtual Linux system !
663 A 2.5.74 kernel is also included in the archive. Just
664 replace the bzImage in qemu.sh to try it.
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.
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.
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
681 ide1=noprobe ide2=noprobe ide3=noprobe ide4=noprobe ide5=noprobe
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}).
691 @section Linux Kernel Compilation
693 You can use any linux kernel with QEMU. However, if you want to use
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:
702 The kernel must be mapped at 0x90000000 (the default is
703 0xc0000000). You must modify only two lines in the kernel source:
705 In @file{include/asm/page.h}, replace
707 #define __PAGE_OFFSET (0xc0000000)
711 #define __PAGE_OFFSET (0x90000000)
714 And in @file{arch/i386/vmlinux.lds}, replace
716 . = 0xc0000000 + 0x100000;
720 . = 0x90000000 + 0x100000;
724 If you want to enable SMP (Symmetric Multi-Processing) support, you
725 must make the following change in @file{include/asm/fixmap.h}. Replace
727 #define FIXADDR_TOP (0xffffX000UL)
731 #define FIXADDR_TOP (0xa7ffX000UL)
733 (X is 'e' or 'f' depending on the kernel version). Although you can
734 use an SMP kernel with QEMU, it only supports one CPU.
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
739 (1000 is the default) as QEMU cannot currently emulate timers at
740 frequencies greater than 100 Hz on host Linux systems < 2.6. In
741 @file{include/asm/param.h}, replace:
744 # define HZ 1000 /* Internal kernel timer frequency */
748 # define HZ 100 /* Internal kernel timer frequency */
753 The file config-2.x.x gives the configuration of the example kernels.
760 As you would do to make a real kernel. Then you can use with QEMU
761 exactly the same kernel as you would boot on your PC (in
762 @file{arch/i386/boot/bzImage}).
767 QEMU has a primitive support to work with gdb, so that you can do
768 'Ctrl-C' while the virtual machine is running and inspect its state.
770 In order to use gdb, launch qemu with the '-s' option. It will wait for a
773 > qemu -s -kernel arch/i386/boot/bzImage -hda root-2.4.20.img -append "root=/dev/hda"
774 Connected to host network interface: tun0
775 Waiting gdb connection on port 1234
778 Then launch gdb on the 'vmlinux' executable:
783 In gdb, connect to QEMU:
785 (gdb) target remote localhost:1234
788 Then you can use gdb normally. For example, type 'c' to launch the kernel:
793 Here are some useful tips in order to use gdb on system code:
797 Use @code{info reg} to display all the CPU registers.
799 Use @code{x/10i $eip} to display the code at the PC position.
801 Use @code{set architecture i8086} to dump 16 bit code. Then use
802 @code{x/10i $cs*16+*eip} to dump the code at the PC position.
805 @chapter QEMU User space emulator invocation
809 In order to launch a Linux process, QEMU needs the process executable
810 itself and all the target (x86) dynamic libraries used by it.
814 @item On x86, you can just try to launch any process by using the native
818 qemu-i386 -L / /bin/ls
821 @code{-L /} tells that the x86 dynamic linker must be searched with a
824 @item Since QEMU is also a linux process, you can launch qemu with qemu (NOTE: you can only do that if you compiled QEMU from the sources):
827 qemu-i386 -L / qemu-i386 -L / /bin/ls
830 @item On non x86 CPUs, you need first to download at least an x86 glibc
831 (@file{qemu-runtime-i386-XXX-.tar.gz} on the QEMU web page). Ensure that
832 @code{LD_LIBRARY_PATH} is not set:
835 unset LD_LIBRARY_PATH
838 Then you can launch the precompiled @file{ls} x86 executable:
841 qemu-i386 tests/i386/ls
843 You can look at @file{qemu-binfmt-conf.sh} so that
844 QEMU is automatically launched by the Linux kernel when you try to
845 launch x86 executables. It requires the @code{binfmt_misc} module in the
848 @item The x86 version of QEMU is also included. You can try weird things such as:
850 qemu-i386 /usr/local/qemu-i386/bin/qemu-i386 /usr/local/qemu-i386/bin/ls-i386
859 @item Ensure that you have a working QEMU with the x86 glibc
860 distribution (see previous section). In order to verify it, you must be
864 qemu-i386 /usr/local/qemu-i386/bin/ls-i386
867 @item Download the binary x86 Wine install
868 (@file{qemu-XXX-i386-wine.tar.gz} on the QEMU web page).
870 @item Configure Wine on your account. Look at the provided script
871 @file{/usr/local/qemu-i386/bin/wine-conf.sh}. Your previous
872 @code{$@{HOME@}/.wine} directory is saved to @code{$@{HOME@}/.wine.org}.
874 @item Then you can try the example @file{putty.exe}:
877 qemu-i386 /usr/local/qemu-i386/wine/bin/wine /usr/local/qemu-i386/wine/c/Program\ Files/putty.exe
882 @section Command line options
885 usage: qemu-i386 [-h] [-d] [-L path] [-s size] program [arguments...]
892 Set the x86 elf interpreter prefix (default=/usr/local/qemu-i386)
894 Set the x86 stack size in bytes (default=524288)
901 Activate log (logfile=/tmp/qemu.log)
903 Act as if the host page size was 'pagesize' bytes