Difference between revisions of "QEMU"

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* [http://tuxology.net/2008/12/14/embedded-emulator/ Building an embedded Linux system emulator using Qemu]
 
* [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]])
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 +
= 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
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rsync -a busybox/_install/ /mnt/rootfs
 +
chown -R root:root /mnt/rootfs/
 +
sync
 +
 +
== 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
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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

Revision as of 18:27, 5 February 2009

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
  • Sparc
  • PowerPC
  • MIPS
  • Coldfie

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

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