Introduction
************

Features
========

QEMU is a FAST! processor emulator using dynamic translation to achieve good emulation speed.

QEMU has two operating modes:

  - Full system emulation. In this mode, QEMU emulates a full system (for example a PC), including a processor and various peripherials. It can be used to launch different Operating Systems without rebooting the PC or to debug system code.

  - User mode emulation (Linux host only). In this mode, QEMU can launch Linux processes compiled for one CPU on another CPU. It can be used to launch the Wine Windows API emulator (http://www.winehq.org) or to ease cross-compilation and cross-debugging.

As QEMU requires no host kernel driver to run, it is very safe and easy to use.

For system emulation, the following hardware targets are supported:

  * PC (x86 processor)

  * PREP (PowerPC processor)

For user emulation, x86, PowerPC, ARM, and SPARC CPUs are supported.

Installation
************

Linux
=====

If you want to compile QEMU, please read the README which gives the related information. Otherwise just download the binary distribution (qemu-XXX-i386.tar.gz) and untar it as root in /:

     su
     cd /
     tar zxvf /tmp/qemu-XXX-i386.tar.gz

Windows
=======

w

  * Install the current versions of MSYS and MinGW from http://www.mingw.org/. You can find detailed installation instructions in the download section and the FAQ.

  * Download the MinGW development library of SDL 1.2.x (SDL-devel-1.2.x-mingw32.tar.gz) from http://www.libsdl.org. Unpack it in a temporary place, and unpack the archive i386-mingw32msvc.tar.gz in the MinGW tool directory. Edit the sdl-config script so that it gives the correct SDL directory when invoked.

  * Extract the current version of QEMU.

  * Start the MSYS shell (file msys.bat).

  * Change to the QEMU directory. Launch ./configure and make.  If you have problems using SDL, verify that sdl-config can be launched from the MSYS command line.

  * You can install QEMU in Program Files/Qemu by typing make install. Don't forget to copy SDL.dll in Program Files/Qemu.

Cross compilation for Windows with Linux
========================================

  * Install the MinGW cross compilation tools available at http://www.mingw.org/.

  * Install the Win32 version of SDL (http://www.libsdl.org) by unpacking i386-mingw32msvc.tar.gz. Set up the PATH environment variable so that i386-mingw32msvc-sdl-config can be launched by the QEMU configuration script.

  * Configure QEMU for Windows cross compilation:

          ./configure --enable-mingw32

     If necessary, you can change the cross-prefix according to the prefix choosen for the MinGW tools with --cross-prefix. You can also use --prefix to set the Win32 install path.

  * You can install QEMU in the installation directory by typing make install. Don't forget to copy SDL.dll in the installation directory.

Note: Currently, Wine does not seem able to launch QEMU for Win32.

Mac OS X
========

Mac OS X is currently not supported.

QEMU PC System emulator invocation
**********************************

Introduction
============

The QEMU System emulator simulates a complete PC.

In order to meet specific user needs, two versions of QEMU are available:

 1. qemu-fast uses the host Memory Management Unit (MMU) to simulate the x86 MMU. It is fast but has limitations because the whole 4 GB address space cannot be used and some memory mapped peripherials cannot be emulated accurately yet. Therefore, a specific Linux kernel must be used (see linux_compile).

 2. qemu uses a software MMU. It is about two times slower but gives a more accurate emulation.

QEMU emulates the following PC peripherials:

  - VGA (hardware level, including all non standard modes)

  - PS/2 mouse and keyboard

  - 2 IDE interfaces with hard disk and CD-ROM support

  - Floppy disk

  - up to 6 NE2000 network adapters

  - Serial port

  - Soundblaster 16 card

Quick Start
===========

Download and uncompress the linux image (linux.img) and type:

     qemu linux.img

Linux should boot and give you a prompt.

Invocation
==========

     usage: qemu [options] [disk_image]

DISK_IMAGE is a raw hard disk image for IDE hard disk 0.

General options:

-fda file

-fdb file
     Use FILE as floppy disk 0/1 image (see disk_images).

-hda file

-hdb file

-hdc file

-hdd file
     Use FILE as hard disk 0, 1, 2 or 3 image (see disk_images).

-cdrom file
     Use FILE as CD-ROM image (you cannot use -hdc and and -cdrom at the same time).

-boot [a|c|d]
     Boot on floppy (a), hard disk (c) or CD-ROM (d). Hard disk boot is the default.

-snapshot
     Write to temporary files instead of disk image files. In this case, the raw disk image you use is not written back. You can however force the write back by pressing C-a s (see disk_images).

-m megs
     Set virtual RAM size to MEGS megabytes.

-initrd file
     Use FILE as initial ram disk.

-nographic

     Normally, QEMU uses SDL to display the VGA output. With this option, you can totally disable graphical output so that QEMU is a simple command line application. The emulated serial port is redirected on the console. Therefore, you can still use QEMU to debug a Linux kernel with a serial console.

-enable-audio

     The SB16 emulation is disabled by default as it may give problems with Windows. You can enable it manually with this option.

Network options:

-n script
     Set TUN/TAP network init script [default=/etc/qemu-ifup]. This script is launched to configure the host network interface (usually tun0) corresponding to the virtual NE2000 card.

-macaddr addr

     Set the mac address of the first interface (the format is aa:bb:cc:dd:ee:ff in hexa). The mac address is incremented for each new network interface.

-tun-fd fd
     Assumes FD talks to a tap/tun host network interface and use it. Read http://bellard.org/qemu/tetrinet.html to have an example of its use.

-user-net
     (Experimental) Use the user mode network stack. This is the default if no tun/tap network init script is found.

-dummy-net
     Use the dummy network stack: no packet will be received on the network cards.

Linux boot specific. When using this options, you can use a given Linux kernel without installing it in the disk image. It can be useful for easier testing of various kernels.

-kernel bzImage
     Use BZIMAGE as kernel image.

-append cmdline
     Use CMDLINE as kernel command line

-initrd file
     Use FILE as initial ram disk.

Debug options:

-s
     Wait gdb connection to port 1234 (see gdb_usage).

-p port
     Change gdb connection port.

-S
     Do not start CPU at startup (you must type 'c' in the monitor).

-d
     Output log in /tmp/qemu.log

During emulation, if you are using the serial console, use C-a h to get terminal commands:

C-a h
     Print this help

C-a x
     Exit emulatior

C-a s
     Save disk data back to file (if -snapshot)

C-a b
     Send break (magic sysrq in Linux)

C-a c
     Switch between console and monitor

C-a C-a
     Send C-a

QEMU Monitor
============

The QEMU monitor is used to give complex commands to the QEMU emulator. You can use it to:

  - Remove or insert removable medias images (such as CD-ROM or floppies)

  - Freeze/unfreeze the Virtual Machine (VM) and save or restore its state from a disk file.

  - Inspect the VM state without an external debugger.

Commands
--------

The following commands are available:

help or ? [cmd]
     Show the help for all commands or just for command CMD.

commit
     Commit changes to the disk images (if -snapshot is used)

info subcommand
     show various information about the system state

     info network
          show the network state

     info block
          show the block devices

     info registers
          show the cpu registers

     info history
          show the command line history

q or quit
     Quit the emulator.

eject [-f] device
     Eject a removable media (use -f to force it).

change device filename
     Change a removable media.

screendump filename
     Save screen into PPM image FILENAME.

log item1[,...]
     Activate logging of the specified items to /tmp/qemu.log.

savevm filename
     Save the whole virtual machine state to FILENAME.

loadvm filename
     Restore the whole virtual machine state from FILENAME.

stop
     Stop emulation.

c or cont
     Resume emulation.

gdbserver [port]
     Start gdbserver session (default port=1234)

x/fmt addr
     Virtual memory dump starting at ADDR.

xp /fmt addr
     Physical memory dump starting at ADDR.

     FMT is a format which tells the command how to format the data. Its syntax is: /{count}{format}{size}

     count
          is the number of items to be dumped.

     format
          can be x (hexa), d (signed decimal), u (unsigned decimal), o (octal), c (char) or i (asm instruction).

     size
          can be b (8 bits), h (16 bits), w (32 bits) or g (64 bits). On x86, h or w can be specified with the i format to respectively select 16 or 32 bit code instruction size.

     Examples:

       * Dump 10 instructions at the current instruction pointer:

               (qemu) x/10i $eip
               0x90107063:  ret
               0x90107064:  sti
               0x90107065:  lea    0x0(%esi,1),%esi
               0x90107069:  lea    0x0(%edi,1),%edi
               0x90107070:  ret
               0x90107071:  jmp    0x90107080
               0x90107073:  nop
               0x90107074:  nop
               0x90107075:  nop
               0x90107076:  nop

       * Dump 80 16 bit values at the start of the video memory.

               (qemu) xp/80hx 0xb8000
               0x000b8000: 0x0b50 0x0b6c 0x0b65 0x0b78 0x0b38 0x0b36 0x0b2f 0x0b42
               0x000b8010: 0x0b6f 0x0b63 0x0b68 0x0b73 0x0b20 0x0b56 0x0b47 0x0b41
               0x000b8020: 0x0b42 0x0b69 0x0b6f 0x0b73 0x0b20 0x0b63 0x0b75 0x0b72
               0x000b8030: 0x0b72 0x0b65 0x0b6e 0x0b74 0x0b2d 0x0b63 0x0b76 0x0b73
               0x000b8040: 0x0b20 0x0b30 0x0b35 0x0b20 0x0b4e 0x0b6f 0x0b76 0x0b20
               0x000b8050: 0x0b32 0x0b30 0x0b30 0x0b33 0x0720 0x0720 0x0720 0x0720
               0x000b8060: 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720
               0x000b8070: 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720
               0x000b8080: 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720
               0x000b8090: 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720

p or print/fmt expr

     Print expression value. Only the FORMAT part of FMT is used.

Integer expressions
-------------------

The monitor understands integers expressions for every integer argument. You can use register names to get the value of specifics CPU registers by prefixing them with $.

Disk Images
===========

Raw disk images
---------------

The disk images can simply be raw images of the hard disk. You can create them with the command:

     dd if=/dev/zero of=myimage bs=1024 count=mysize

where MYIMAGE is the image filename and MYSIZE is its size in kilobytes.

Snapshot mode
-------------

If you use the option -snapshot, all disk images are considered as read only. When sectors in written, they are written in a temporary file created in /tmp. You can however force the write back to the raw disk images by pressing C-a s.

NOTE: The snapshot mode only works with raw disk images.

Copy On Write disk images
-------------------------

QEMU also supports user mode Linux (http://user-mode-linux.sourceforge.net/) Copy On Write (COW) disk images. The COW disk images are much smaller than normal images as they store only modified sectors. They also permit the use of the same disk image template for many users.

To create a COW disk images, use the command:

     qemu-mkcow -f myrawimage.bin mycowimage.cow

myrawimage.bin is a raw image you want to use as original disk image. It will never be written to.

mycowimage.cow is the COW disk image which is created by qemu-mkcow. You can use it directly with the -hdx options. You must not modify the original raw disk image if you use COW images, as COW images only store the modified sectors from the raw disk image. QEMU stores the original raw disk image name and its modified time in the COW disk image so that chances of mistakes are reduced.

If the raw disk image is not read-only, by pressing C-a s you can flush the COW disk image back into the raw disk image, as in snapshot mode.

COW disk images can also be created without a corresponding raw disk image. It is useful to have a big initial virtual disk image without using much disk space. Use:

     qemu-mkcow mycowimage.cow 1024

to create a 1 gigabyte empty COW disk image.

NOTES:

 1. COW disk images must be created on file systems supporting holes such as ext2 or ext3.

 2. Since holes are used, the displayed size of the COW disk image is not the real one. To know it, use the ls -ls command.

Network emulation
=================

QEMU simulates up to 6 networks cards (NE2000 boards). Each card can be connected to a specific host network interface.

Using tun/tap network interface
-------------------------------

This is the standard way to emulate network. QEMU adds a virtual network device on your host (called tun0), and you can then configure it as if it was a real ethernet card.

As an example, you can download the linux-test-xxx.tar.gz archive and copy the script qemu-ifup in /etc and configure properly sudo so that the command ifconfig contained in qemu-ifup can be executed as root. You must verify that your host kernel supports the TUN/TAP network interfaces: the device /dev/net/tun must be present.

See direct_linux_boot to have an example of network use with a Linux distribution.

Using the user mode network stack
---------------------------------

This is experimental (version 0.5.4). You must configure qemu with --enable-slirp. Then by using the option -user-net or if you have no tun/tap init script, QEMU uses a completely user mode network stack (you don't need root priviledge to use the virtual network). The virtual network configuration is the following:

     QEMU Virtual Machine    <------>  Firewall/DHCP server <-----> Internet
          (10.0.2.x)            |          (10.0.2.2)
                                |
                                ---->  DNS
                                   (10.0.2.3)

The QEMU VM behaves as if it was behind a firewall which blocks all incoming connections. You can use a DHCP client to automatically configure the network in the QEMU VM.

In order to check that the user mode network is working, you can ping the address 10.0.2.2 and verify that you got an address in the range 10.0.2.x from the QEMU virtual DHCP server.

Direct Linux Boot
=================

This section explains how to launch a Linux kernel inside QEMU without having to make a full bootable image. It is very useful for fast Linux kernel testing. The QEMU network configuration is also explained.

 1. Download the archive linux-test-xxx.tar.gz containing a Linux kernel and a disk image.

 2. Optional: If you want network support (for example to launch X11 examples), you must copy the script qemu-ifup in /etc and configure properly sudo so that the command ifconfig contained in qemu-ifup can be executed as root. You must verify that your host kernel supports the TUN/TAP network interfaces: the device /dev/net/tun must be present.

     When network is enabled, there is a virtual network connection between the host kernel and the emulated kernel. The emulated kernel is seen from the host kernel at IP address 172.20.0.2 and the host kernel is seen from the emulated kernel at IP address 172.20.0.1.

 3. Launch qemu.sh. You should have the following output:

          > ./qemu.sh
          Connected to host network interface: tun0
          Linux version 2.4.21 (bellard.localdomain) (gcc version 3.2.2 20030222 (Red Hat Linux 3.2.2-5)) #5 Tue Nov 11 18:18:53 CET 2003
          BIOS-provided physical RAM map:
           BIOS-e801: 0000000000000000 - 000000000009f000 (usable)
           BIOS-e801: 0000000000100000 - 0000000002000000 (usable)
          32MB LOWMEM available.
          On node 0 totalpages: 8192
          zone(0): 4096 pages.
          zone(1): 4096 pages.
          zone(2): 0 pages.
          Kernel command line: root=/dev/hda sb=0x220,5,1,5 ide2=noprobe ide3=noprobe ide4=noprobe ide5=noprobe console=ttyS0
          ide_setup: ide2=noprobe
          ide_setup: ide3=noprobe
          ide_setup: ide4=noprobe
          ide_setup: ide5=noprobe
          Initializing CPU#0
          Detected 2399.621 MHz processor.
          Console: colour EGA 80x25
          Calibrating delay loop... 4744.80 BogoMIPS
          Memory: 28872k/32768k available (1210k kernel code, 3508k reserved, 266k data, 64k init, 0k highmem)
          Dentry cache hash table entries: 4096 (order: 3, 32768 bytes)
          Inode cache hash table entries: 2048 (order: 2, 16384 bytes)
          Mount cache hash table entries: 512 (order: 0, 4096 bytes)
          Buffer-cache hash table entries: 1024 (order: 0, 4096 bytes)
          Page-cache hash table entries: 8192 (order: 3, 32768 bytes)
          CPU: Intel Pentium Pro stepping 03
          Checking 'hlt' instruction... OK.
          POSIX conformance testing by UNIFIX
          Linux NET4.0 for Linux 2.4
          Based upon Swansea University Computer Society NET3.039
          Initializing RT netlink socket
          apm: BIOS not found.
          Starting kswapd
          Journalled Block Device driver loaded
          Detected PS/2 Mouse Port.
          pty: 256 Unix98 ptys configured
          Serial driver version 5.05c (2001-07-08) with no serial options enabled
          ttyS00 at 0x03f8 (irq = 4) is a 16450
          ne.c:v1.10 9/23/94 Donald Becker (becker.com)
          Last modified Nov 1, 2000 by Paul Gortmaker
          NE*000 ethercard probe at 0x300: 52 54 00 12 34 56
          eth0: NE2000 found at 0x300, using IRQ 9.
          RAMDISK driver initialized: 16 RAM disks of 4096K size 1024 blocksize
          Uniform Multi-Platform E-IDE driver Revision: 7.00beta4-2.4
          ide: Assuming 50MHz system bus speed for PIO modes; override with idebus=xx
          hda: QEMU HARDDISK, ATA DISK drive
          ide0 at 0x1f0-0x1f7,0x3f6 on irq 14
          hda: attached ide-disk driver.
          hda: 20480 sectors (10 MB) w/256KiB Cache, CHS=20/16/63
          Partition check:
           hda:
          Soundblaster audio driver Copyright (C) by Hannu Savolainen 1993-1996
          NET4: Linux TCP/IP 1.0 for NET4.0
          IP Protocols: ICMP, UDP, TCP, IGMP
          IP: routing cache hash table of 512 buckets, 4Kbytes
          TCP: Hash tables configured (established 2048 bind 4096)
          NET4: Unix domain sockets 1.0/SMP for Linux NET4.0.
          EXT2-fs warning: mounting unchecked fs, running e2fsck is recommended
          VFS: Mounted root (ext2 filesystem).
          Freeing unused kernel memory: 64k freed

          Linux version 2.4.21 (bellard.localdomain) (gcc version 3.2.2 20030222 (Red Hat Linux 3.2.2-5)) #5 Tue Nov 11 18:18:53 CET 2003

          QEMU Linux test distribution (based on Redhat 9)

          Type 'exit' to halt the system

          sh-2.05b#

 4. Then you can play with the kernel inside the virtual serial console. You can launch ls for example. Type Ctrl-a h to have an help about the keys you can type inside the virtual serial console. In particular, use Ctrl-a x to exit QEMU and use Ctrl-a b as the Magic SysRq key.

 5. If the network is enabled, launch the script /etc/linuxrc in the emulator (don't forget the leading dot):

          . /etc/linuxrc

     Then enable X11 connections on your PC from the emulated Linux:

          xhost +172.20.0.2

     You can now launch xterm or xlogo and verify that you have a real Virtual Linux system !

NOTES:

 1. A 2.5.74 kernel is also included in the archive. Just replace the bzImage in qemu.sh to try it.

 2. qemu-fast creates a temporary file in $QEMU_TMPDIR (/tmp is the default) containing all the simulated PC memory. If possible, try to use a temporary directory using the tmpfs filesystem to avoid too many unnecessary disk accesses.

 3. In order to exit cleanly from qemu, you can do a shutdown inside qemu. qemu will automatically exit when the Linux shutdown is done.

 4. You can boot slightly faster by disabling the probe of non present IDE interfaces. To do so, add the following options on the kernel command line:

          ide1=noprobe ide2=noprobe ide3=noprobe ide4=noprobe ide5=noprobe

 5. The example disk image is a modified version of the one made by Kevin Lawton for the plex86 Project (www.plex86.org).

Linux Kernel Compilation
========================

You can use any linux kernel with QEMU. However, if you want to use qemu-fast to get maximum performances, you must use a modified guest kernel. If you are using a 2.6 guest kernel, you can use directly the patch linux-2.6-qemu-fast.patch made by Rusty Russel available in the QEMU source archive. Otherwise, you can make the following changes by hand to the Linux kernel:

 1. The kernel must be mapped at 0x90000000 (the default is 0xc0000000). You must modify only two lines in the kernel source:

     In include/asm/page.h, replace

          #define __PAGE_OFFSET           (0xc0000000)

     by

          #define __PAGE_OFFSET           (0x90000000)

     And in arch/i386/vmlinux.lds, replace

            . = 0xc0000000 + 0x100000;

     by

            . = 0x90000000 + 0x100000;

 2. If you want to enable SMP (Symmetric Multi-Processing) support, you must make the following change in include/asm/fixmap.h. Replace

          #define FIXADDR_TOP	(0xffffX000UL)

     by

          #define FIXADDR_TOP	(0xa7ffX000UL)

     (X is 'e' or 'f' depending on the kernel version). Although you can use an SMP kernel with QEMU, it only supports one CPU.

 3. If you are not using a 2.6 kernel as host kernel but if you use a target 2.6 kernel, you must also ensure that the 'HZ' define is set to 100 (1000 is the default) as QEMU cannot currently emulate timers at frequencies greater than 100 Hz on host Linux systems < 2.6. In include/asm/param.h, replace:

          # define HZ		1000		/* Internal kernel timer frequency */

     by

          # define HZ		100		/* Internal kernel timer frequency */

The file config-2.x.x gives the configuration of the example kernels.

Just type

     make bzImage

As you would do to make a real kernel. Then you can use with QEMU exactly the same kernel as you would boot on your PC (in arch/i386/boot/bzImage).

GDB usage
=========

QEMU has a primitive support to work with gdb, so that you can do 'Ctrl-C' while the virtual machine is running and inspect its state.

In order to use gdb, launch qemu with the '-s' option. It will wait for a gdb connection:

     > qemu -s -kernel arch/i386/boot/bzImage -hda root-2.4.20.img -append "root=/dev/hda"
     Connected to host network interface: tun0
     Waiting gdb connection on port 1234

Then launch gdb on the 'vmlinux' executable:

     > gdb vmlinux

In gdb, connect to QEMU:

     (gdb) target remote localhost:1234

Then you can use gdb normally. For example, type 'c' to launch the kernel:

     (gdb) c

Here are some useful tips in order to use gdb on system code:

 1. Use info reg to display all the CPU registers.

 2. Use x/10i $eip to display the code at the PC position.

 3. Use set architecture i8086 to dump 16 bit code. Then use x/10i $cs*16+*eip to dump the code at the PC position.

QEMU PREP PowerPC System emulator invocation
********************************************

Use the executable qemu-system-ppc to simulate a complete PREP PowerPC system.

QEMU emulates the following PREP peripherials:

  - 2 IDE interfaces with hard disk and CD-ROM support

  - Floppy disk

  - up to 6 NE2000 network adapters

  - Serial port

  - PREP Non Volatile RAM

You can read the qemu PC system emulation chapter to have more informations about QEMU usage.

More information is available at http://jocelyn.mayer.free.fr/qemu-ppc/.

QEMU User space emulator invocation
***********************************

Quick Start
===========

In order to launch a Linux process, QEMU needs the process executable itself and all the target (x86) dynamic libraries used by it.

  * On x86, you can just try to launch any process by using the native libraries:

          qemu-i386 -L / /bin/ls

     -L / tells that the x86 dynamic linker must be searched with a / prefix.

  * 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):

          qemu-i386 -L / qemu-i386 -L / /bin/ls

  * On non x86 CPUs, you need first to download at least an x86 glibc (qemu-runtime-i386-XXX-.tar.gz on the QEMU web page). Ensure that LD_LIBRARY_PATH is not set:

          unset LD_LIBRARY_PATH

     Then you can launch the precompiled ls x86 executable:

          qemu-i386 tests/i386/ls

     You can look at qemu-binfmt-conf.sh so that QEMU is automatically launched by the Linux kernel when you try to launch x86 executables. It requires the binfmt_misc module in the Linux kernel.

  * The x86 version of QEMU is also included. You can try weird things such as:

          qemu-i386 /usr/local/qemu-i386/bin/qemu-i386 /usr/local/qemu-i386/bin/ls-i386

Wine launch
===========

  * Ensure that you have a working QEMU with the x86 glibc distribution (see previous section). In order to verify it, you must be able to do:

          qemu-i386 /usr/local/qemu-i386/bin/ls-i386

  * Download the binary x86 Wine install (qemu-XXX-i386-wine.tar.gz on the QEMU web page).

  * Configure Wine on your account. Look at the provided script /usr/local/qemu-i386/bin/wine-conf.sh. Your previous ${HOME}/.wine directory is saved to ${HOME}/.wine.org.

  * Then you can try the example putty.exe:

          qemu-i386 /usr/local/qemu-i386/wine/bin/wine /usr/local/qemu-i386/wine/c/Program\ Files/putty.exe

Command line options
====================

     usage: qemu-i386 [-h] [-d] [-L path] [-s size] program [arguments...]

-h
     Print the help

-L path
     Set the x86 elf interpreter prefix (default=/usr/local/qemu-i386)

-s size
     Set the x86 stack size in bytes (default=524288)

Debug options:

-d
     Activate log (logfile=/tmp/qemu.log)

-p pagesize
     Act as if the host page size was 'pagesize' bytes