Difference between revisions of "QEMU"

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(Added links for using QEMU on the RPi (transferred from RPi Development environments))
 
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When used as a virtualizer, QEMU achieves near native performances by executing the guest code directly on the host CPU. A host driver called the QEMU accelerator (also known as KQEMU) is needed in this case. The virtualizer mode requires that both the host and guest machine use x86 compatible processors.
 
When used as a virtualizer, QEMU achieves near native performances by executing the guest code directly on the host CPU. A host driver called the QEMU accelerator (also known as KQEMU) is needed in this case. The virtualizer mode requires that both the host and guest machine use x86 compatible processors.
  
[http://www.qemu.org Qemu project web site]
+
[http://www.qemu.org QEMU project web site]
  
 
= Use in embedded projects =
 
= Use in embedded projects =
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* x86
 
* x86
* Arm
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* [http://www.nongnu.org/qemu/qemu-doc.html#SEC65 ARM] (ARM Integrator/CP, ARM Versatile, ARM Realview, X-Scale based PDAs, Palm Tungsten, Nokia N800/N810 tablets, Luminary boards, etc.)
* Sparc
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* [http://www.nongnu.org/qemu/qemu-doc.html#SEC65 Sparc32] and [http://www.nongnu.org/qemu/qemu-doc.html#SEC63 Sparc64]
* PowerPC
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* [http://www.nongnu.org/qemu/qemu-doc.html#SEC61 PowerPC]
* MIPS
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* [http://www.nongnu.org/qemu/qemu-doc.html#SEC61 MIPS]
* Coldfie
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* [http://www.nongnu.org/qemu/qemu-doc.html#SEC66 Coldfire]
 +
 
 +
Support for new boards or new peripherals can added relatively easily in QEMU, the APIs being quite simple to understand and use.
  
 
= Resources =
 
= Resources =
* [http://www.bellard.org/qemu/user-doc.html QEMU Emulator User Documentation]
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* [http://wiki.qemu.org/download/qemu-doc.html QEMU Emulator User Documentation]
* [http://www.bellard.org/qemu/qemu-tech.html QEMU Internals]
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* [http://www.bellard.org/qemu/qemu-tech.html QEMU Internals] (broken link --[[User:Klausfpga|Klausfpga]] 16:48, 14 May 2009 (UTC) )
* [http://tuxology.net/2008/12/14/embedded-emulator/ Building an embedded Linux system emulator using Qemu]
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* [http://wiki.qemu.org/KQemu/TechDoc QEMU Accelerator Technical Documentation]
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* [http://tuxology.net/2008/12/14/embedded-emulator/ Building an embedded Linux system emulator using QEMU]
 
* [http://vm-kernel.org/blog/2008/12/15/linux-is-running-on-qemu-omap3/ QEMU for OMAP3] ([[BeagleBoard]])
 
* [http://vm-kernel.org/blog/2008/12/15/linux-is-running-on-qemu-omap3/ QEMU for OMAP3] ([[BeagleBoard]])
 +
* [[QEMUonARM|QEMU on ARM]]
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* [http://cronicasredux.blogspot.co.uk/2011/09/installing-and-running-debian-armel-on.html QEMU for the Raspberry Pi] - also see [http://www.raspberrypi.org/forum/projects-and-collaboration-general/emulating-a-raspi-on-windows discussion]
 +
 +
= Some quick useful tips =
 +
== How to build a rootfs.img ==
 +
Here are the steps for building a rootfs.img, assuming you busybox built on your host, for the target archictecture:
 +
mkdir /mnt/rootfs
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mount -o loop rootfs.img /mnt/rootfs
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rsync -a busybox/_install/ /mnt/rootfs
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chown -R root:root /mnt/rootfs/
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sync
 +
umount
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 +
== Some sample command lines ==
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I got these from Rob Landley at OLS 2008:
 +
 +
qemu -kernel linux-2.6.26/arch/i386/boot/bzImage -hda rootfs.img -append "console=ttyS0 root=/dev/hda" -nographic
 +
 +
qemu -kernel linux-2.6.26/arch/i386/boot/bzImage -hda rootfs.img -append "console=ttyS0 root=/dev/hda init=/bin/ash" -nographic
 +
 +
qemu -kernel linux-2.6.26/arch/i386/boot/bzImage -hda rootfs.img -append "console=ttyS0 root=/dev/hda panic=1" -nographic -no-reboot
 +
 +
killall qemu
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 +
=== Interesting options ===
 +
* -kernel <file> = specify the kernel image to use for booting
 +
* -hda <file> = specify
 +
* -nographic = don't use graphics, and redirect serial I/O to console
 +
* -no-reboot = exit instead of rebooting
 +
 +
== Resize filesystem image ==
 +
Not enough space to install anything after you're up and running? Here's how to resize the image.
 +
 +
Host:  qemu-img resize rootfs_debian6_rpi.ext4 +1G
 +
QEMU:  sudo resize2fs /dev/sda  // Be careful not to run this on your host machine
 +
 +
The online resize2fs may corrupt the filesystem so here's an alternative.
 +
[http://www.cnx-software.com/2012/03/08/instructions-to-run-raspberry-pi-fedora-14-remix-in-qemu/#comment-6900 resize using loopback device]
 +
[[Category:QEMU]]

Latest revision as of 18:43, 24 November 2012

Introduction

QEMU is a generic and open source machine emulator and virtualizer, originally developed by Fabrice Bellard.

When used as a machine emulator, QEMU can run OSes and programs made for one machine (e.g. an ARM board) on a different machine (e.g. your own PC). By using dynamic translation, it achieves very good performances.

When used as a virtualizer, QEMU achieves near native performances by executing the guest code directly on the host CPU. A host driver called the QEMU accelerator (also known as KQEMU) is needed in this case. The virtualizer mode requires that both the host and guest machine use x86 compatible processors.

QEMU project web site

Use in embedded projects

QEMU is increasingly used to provide an emulator for embedded processors, for testing embedded Linux without the need for actual hardware.

The Embedded Linux From Scratch presentation by Michael Opdenacker has great information about setting up QEMU with embedded Linux.

Also, Firmware Linux uses QEMU as part of a "native" build environment to eliminate cross-compilation problems when building for Embedded Linux distributions for non-X86 platforms.

Supported architectures

The following architectures are supported as target architectures for system emulation:

  • x86
  • ARM (ARM Integrator/CP, ARM Versatile, ARM Realview, X-Scale based PDAs, Palm Tungsten, Nokia N800/N810 tablets, Luminary boards, etc.)
  • Sparc32 and Sparc64
  • PowerPC
  • MIPS
  • Coldfire

Support for new boards or new peripherals can added relatively easily in QEMU, the APIs being quite simple to understand and use.

Resources

Some quick useful tips

How to build a rootfs.img

Here are the steps for building a rootfs.img, assuming you busybox built on your host, for the target archictecture:

mkdir /mnt/rootfs
mount -o loop rootfs.img /mnt/rootfs
rsync -a busybox/_install/ /mnt/rootfs
chown -R root:root /mnt/rootfs/
sync
umount

Some sample command lines

I got these from Rob Landley at OLS 2008:

qemu -kernel linux-2.6.26/arch/i386/boot/bzImage -hda rootfs.img -append "console=ttyS0 root=/dev/hda" -nographic
qemu -kernel linux-2.6.26/arch/i386/boot/bzImage -hda rootfs.img -append "console=ttyS0 root=/dev/hda init=/bin/ash" -nographic
qemu -kernel linux-2.6.26/arch/i386/boot/bzImage -hda rootfs.img -append "console=ttyS0 root=/dev/hda panic=1" -nographic -no-reboot
killall qemu

Interesting options

  • -kernel <file> = specify the kernel image to use for booting
  • -hda <file> = specify
  • -nographic = don't use graphics, and redirect serial I/O to console
  • -no-reboot = exit instead of rebooting

Resize filesystem image

Not enough space to install anything after you're up and running? Here's how to resize the image.

Host:  qemu-img resize rootfs_debian6_rpi.ext4 +1G
QEMU:  sudo resize2fs /dev/sda  // Be careful not to run this on your host machine

The online resize2fs may corrupt the filesystem so here's an alternative. resize using loopback device