Emulation on a Linux PC

Question

How can I connect an SD card containing a Raspberry Pi OS to my Linux PC, and boot the OS in an emulator?

Why won't VMWare work?

What are the limitations of this method?

Related: Emulation on a Windows PC

Answer 1

Yes this is completely possible. However, in reality it's a little bit different to how you are thinking.

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Preamble

The SD card contains an image of the operating system. And works by inflating this image when the device is powered on.

As I expect you already know, you flash this image onto the SD card in order to create a working system. However, what you can do before you flash the image is have a play around with it using QEMU, which is a processor emulator, and allows us to emulate the ARM instruction set.

In this way, any changes you make to the image (installing, compiling etc) will still be there after you flash it to the SD card.

I'll now talk you through how to use QEMU to load the image. I will be demonstrating with the Arch Linux image, but the process should be the same regardless.

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Using QEMU

Prerequesites

You will need to acquire QEMU for your system. QEMU should only have one requirement, in order in input devices to work you need to have the SDL development package installed, which should be available from your package manager.

I recommend downloading the package using your regular package manager:

Arch:

sudo pacman -S sdl qemu

Ubuntu:

sudo apt-get install libsdl-dev
sudo add-apt-repository ppa:linaro-maintainers/tools
sudo apt-get update
sudo apt-get install qemu-system

Building QEMU yourself

Alternatively, you can build QEMU yourself. This is great if you want to try a new version, but it can be slow and be prepared for lots of errors during compilation! Note that if building QEMU from their website it must be compiled for ARM support. So check your distro repositories first. This can be done like so;

mkdir rpi-emu && cd rpi-emu
wget http://wiki.qemu.org/download/qemu-1.1.0-1.tar.bz2
tar xvjf qemu-1.1.0-1.tar.bz2
cd qemu-1.1.0-1
./configure –target-list=arm-softmmu,arm-linux-user
make
sudo make install

Verify that you have ARM support with:

qemu-system-arm --version
QEMU emulator version 1.0,1, Copyright (c) 2003-2008 Fabrice Bellard

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Obtaining the Image

We're working with Arch Linux, so will be using the Arch Arm image. But replace this with whatever you wish to work with, or perhaps you already have an image. In which case, skip this step.

wget http://anorien.csc.warwick.ac.uk/mirrors/raspberrypi.org/images/archlinuxarm/archlinuxarm-29-04-2012/archlinuxarm-29-04-2012.zip
unzip archlinuxarm-29-04-2012.zip 

For QEMU to work we also need the kernel image (which would be inside the .img file).

Note: I don't think this step is necessary for Debian. Someone please confirm.

Luckily there are precompiled images available, and you can use the one from here (direct download).

TODO: Demonstrate how to compile a kernel image here?

Starting the VM

You should now have:

• An img file which you can verify using the supplied sha1 (recommended).
• A kernel image (zImage).
• QEMU for ARM.

The Virtual Machine can now be started using the following long-winded command:

qemu-system-arm -kernel zImage -cpu arm1176 -M versatilepb -serial stdio -append "root=/dev/sda2" -hda archlinuxarm-29-04-2012.img -clock dynticks

Note that you will only have several hundred megabytes of storage using this method (whatever is spare on the image). A virtual hard disk can be created by following the QEMU user guide.

Answer 2

You cannot do what you're suggesting, because Raspberry Pi has a different processor architecture than most PCs. While most PCs are x86-based, RPi is an ARM-based computer.

This is the same reason as why you cannot run, for example, Microsoft Windows on RPi.

VmWare won't work, because it can only virtualize x86-based operating systems (32-bit and 64-bit). There are other emulators that can virtualize ARM, such as QEMU, but those are running full software emulation without native CPU virtualizaton support, so you can expect them to be quite slow.