Raspberry Pi Emulator in Ubuntu with Qemu

The Raspberry Pi board is a low cost board based on Broadcom BCM2835 media processor SoC with an ARM1176JZF-S core clocked at 700MHz. This board is currently under development and should be ready by end of November, beginning of December and will be sold for 25 USD (128MB RAM – no Ethernet) and 35 USD (256MB RAM – Ethernet).

While we are waiting for the board, we can still test software using qemu to emulate a board based on an ARM1176 core with 128MB or 256 MB memory.

I’ve tried to create a rootfs based on Ubuntu with rootstock but this only support processors with ARM cortex A8 and greater, so it would not work with ARM11. I’ll be using Debian Squeeze instead.

Prerequisites

My host computer is running Ubuntu 10.04.3 LTS, but any recent Ubuntu or Debian installation should work with these instructions. [Update: You won’t be able to install qemu-linaro in Debian.  [Update in update: Apparently in the latest version of Debian Squeeze, you can just install the default qemu image: apt-get install qemu-system. The build instructions below are for reference in case you use a distro with an older qemu]

You need to cross-compile qemu as follows:


This also seems much faster than Linaro Qemu.]

I’m using qemu-linaro, here’s how to install it:


Here’s the version I use for reference:

Building the kernel for ARM11

I will basically follow the very clear instructions given at http://raspi.springnote.com/pages/8234994 with some slight modifications. I’ll skip some explanations so refer to the link above to understand exactly what you are doing.

First create a working direcory:


Download the latest  Sourcery G++ Lite IA32 GNU/Linux TAR package for EABI to your working directory and extract it:


Download, extract and patch the kernel for ARMv6 support:


Configure the kernel:


Specify the cross-compiler:


In my case I entered “/home/jaufranc/edev/raspberry-pi/arm-2011.03/bin/arm-none-eabi-“.

Select the right CPU options:


Enable ARM EABI:


Enable qemu’s disk support:


Enable devtmpfs:


Enable tmpfs:


Enable the event interface:


Exit and save the configuration.

Now compile the kernel:

Generating ARMEL Debian Squeeze Rootfs

The kernel build will take a while, so in the meantine you can open another terminal window and prepare the rootfs.

Create an empty rootfs directory and retrieve an armel rootfs for Debian Squeeze:


Once the kernel above is built and debootsrap has completed install the kernel modules in the rootfs:


The first stage of the rootfs is complete. You’ll notice some important script (e.g. inittab) are missing at this point, but this is normal.

Now let’s create an empty ext2 rootfs (3GB) and copy the rootfs we’ve just created to it:


To complete the rootfs, we’ll need to copy the kernel image the working directory and run qemu as follows:


Once you have access to the command line, mount the proc filesystem and complete the bootstrapping process:


The final steps are to enable the network, give a hostname and create a temporary root password:


That’s it your system is now ready.

You can stop qemu and restart it as follows:


Login as root with your temporary password and you should be asked to change it. After you have access to the command line and can check the CPU details with cat /proc/cpuinfo

You can compile your own program using the cross-toolchain installed above

For those who want to skip the steps to build the kernel and generate the rootfs and just want to run qemu, I’ve uploaded the binary files:

After you download rootfs.ext2.gz you’ll need to unzip it first:


The root password is raspberry for the rootfs above.

If you want to install armel binaries using apt-get like you would do on a PC distribution, edit /etc/apt/sources.list as follows:


and run:


Sources:

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52 Replies to “Raspberry Pi Emulator in Ubuntu with Qemu”

  1. Really great tutorial, great fun compliling linux for the first time, be warned their are a few spelling mistakes and the rootfs loads better if you use. sudo qemu-system-arm -M versatilepb -cpu arm1176 -hda YOURROOTFSFILE -kernel YOURKERNELFILE -append “root=/dev/sda”. but real good fun playing with the software before the board is available

  2. @cnxsoft
    Still using the files that you provided can’t get the rootfs to mount for love or toffee. Might have to start again. but so far (with a dist-upgrade) got an lxde desktop running. hehe not bad when it is emulating on an old sempron 3000. very much liking qemu as a multi cpu test platform

  3. Having some trouble with the compile on a Linux Mint 11 (i386) system.

    The first problem was resulted in these errors:

    cc1: error: unrecognized command line option “-mlittle-endian”
    cc1: error: unrecognized command line option “-mapcs”
    cc1: error: unrecognized command line option “-mno-sched-prolog”

    One post for another environment suggested that CROSS_COMPILE was incorrect.

    I updated the Makefile with this line:

    CROSS_COMPILE = ~/edev/arm-2011.03/bin/arm-none-eabi-

    This attempt got further but there were several of these warnings:

    warning: “__LINUX_ARM_ARCH__” is not defined

    followed by

    linux-3.0.4/arch/arm/include/asm/glue-df.h:107:2: error: #error Unknown data abort handler type
    In file included from arch/arm/kernel/asm-offsets.c:18:0:
    linux-3.0.4/arch/arm/include/asm/glue-pf.h:54:2: error: #error Unknown prefetch abort handler type
    make[1]: *** [arch/arm/kernel/asm-offsets.s] Error 1

    Repeating the entire process from scratch had the same results.

    Can you explain what I am doing wrong?

    Thank you

  4. I checked the Bash history and my menuconfig matches the instructions: make ARCH=arm menuconfig

    I have successfully built kernels before with menuconfig having started out with Slackware.

  5. @Mark Johnson
    The two differences I see:
    1. My .config has CONFIG_ARM_PATCH_PHYS_VIRT=y
    2. My .config uses the full path for CONFIG_CROSS_COMPILE=”/home/jaufranc/edev/raspberry-pi/arm-2011.03/bin/arm-none-eabi-” but yours just uses CONFIG_CROSS_COMPILE=”arm-none-eabi-“, so it could potentially use another cross-compiler that is in your PATH.

    I also enabled ext4 in my config, but I suppose it should not be related to your issue.

  6. @cnxsoft

    Thanks for the suggestions.

    I chased down CONFIG_ARM_PATCH_PHYS_VIRT to the very first line in the menuconfig screen: [] Patch physical to virtual translations at runtime (EXPERIMENTAL)

    Enabling it (which is not in the instructions) resulted in the .config containing CONFIG_ARM_PATCH_PHYS_VIRT=y but it did not help.

    Attempting to make after that results in warnings for __LINUX_ARM_ARCH__ being undefined. Of course, that can be defined, but regardless, there is an error due to CPU_PABORT_HANDLER being undefined.

    I’m about ready to throw in the towel. Once the hardware comes out, there should be a stable build environment.

  7. Thanks for the great guide!
    Works perfectly.

    I just spotted one small typo:
    Instead of “mount /proc /proc -t /proc” it should be “mount /proc /proc -t proc”

  8. In case somebody tries to use more than 256 MB RAM, qemu will crash because versatile does not support more than 256 MB. Newer version of qemu will return an error instead of crashing however.

  9. apt-get install qemu-system works for debian, too. No need to muck around with compiling.

    If like me you want to run this on a remote box with no monitor, the command changes to:

    qemu-system-arm -M versatilepb -cpu arm1176 -m 256 -hda rootfs.ext2 -kernel zImage -append “root=/dev/sda console=ttyAMA00” -nographic

    To enable the serial console you need to add the line:

    T0:23:respawn:/sbin/getty -L ttyAMA0 9600 vt100

    To /etc/inittab

    Also add

    ttyAMA0

    To /etc/securetty

    I’m impressed how speedy it is, even running on a Microserver it’s perfectly usable. CPU emulation has come a long way..

  10. @Tony
    Thanks for the update and headless instructions. I suppose the recent Debian release has also updated Qemu, as before I would just get an error like “CPU not supported”.
    I’m also wondering why you would use the serial port, when you can use ssh to connect to the emulator (unless I did not install dropbear in that image…)

  11. Great tutorial, thank you very much.

    Do you have an idea how to make the RTC (real time clock) work?

    Whenever I launch QEMU, system time is set to January 1st, 1970. Calling “hwclock” leads to the error “Cannot access the Hardware Clock via any known method”.

    Any help is appreciated.

    1. I’m not sure qemu can emulate the real time clock. I’ve just installed the ntp daemon:
      apt-get install ntp

      It will get the code from the network. This should also solve the issue where you have to change the root password each time you login.

  12. I cannot access any USB devices I provide to the virtual machine. Is the kernel correctly configured for Qemu’s USB controller? If yes, I may be missing something in my Debian installation …

  13. @ Benny
    I haven’t tried this. You could try to add “-usb -usbdevice host::” to the QEMU command line. If you don’t know the VID/PID of your USB device, you can use “lsusb” or “cat /proc/bus/usb/devices” to retrieve them.

  14. @ cnxsoft
    I managed to enable USB by making some more adjustments to the kernel config from above:

    Device Drivers ->
    [*] USB support ->
    Support for Host-side USB
    OHCI HCD support
    USB Mass Storage support

    Without this, Qemu’s USB controller will not work (“-usb -usbdevice …” parameters not having any effect). Please note that this is only a minimum USB config, allowing standard USB drives to be accessed. There are many more potential USB options for the kernel …

    For FAT-formatted USB drives, I also had to enable an additional codepage (otherwise mounting such devices will fail):

    File systems ->
    {M} Native language support ->
    Codepage 437 (United States, Canada)

  15. I’m having trouble getting past the “sudo debootstrap –foreign –arch armel squeeze debian_armel_squeeze http://ftp.debian.org/debian” step on Ubuntu 11.10. It brings up a “sudo: debootstrap: command not found” error, and unless there was some typo that I’m not aware of, I dunno what’s wrong with it. This is my first time trying anything like this, so I’m a wee bit clueless compared to the rest of you folk.

  16. One point you did not address is how to route network traffic through QEMU.
    My Raspberry machine has a healthy IP address of 10.0.2.15, but QEMU does not route that anywhere.
    What do I need to do so apt-get will work within the Raspberry machine?
    Thanks!

  17. @Rmm200
    I have the same IP address in qemu, and apt-get works out of the box. There is nothing to do to route the traffic to qemu if the traffic originates from qemu (client). If you run a server in qemu, you’d have to use redir option or configure a tap interface in the qemu command line.

    Can you ping outside, e.g. ping yahoo.com ?
    If yes, have you already configured /etc/apt/sources.list as described at the end of the post ?

  18. Full configuration is running Ubuntu 11.10 under VMWare. Firefox – and apt-get – work fine to the Internet on Ubuntu. I am running qemu in a terminal window on the Ubuntu machine. From the qemu client, I can ping 10.0.2.2 successfully (the net is up and working), but ping to 192.168.1.1 (my router) never gets a response back. My Ubuntu machine uses bridged ethernet to the host. I have not set up any routing tables on the Ubuntu machine. Surprisingly, ping yahoo.com responds with: PING yahoo.com (98.139.183.24) as if DNS was working, but never gets a response from Yahoo.
    Ring any bells?

  19. @Rmm200
    I had also tried it in Virtual Box previously and it worked. However, I never tried with VMWare. But since you are using bridged mode it should not be the issue.
    What happens when you run apt-get update ?

  20. Bah – apt-get update works great. I used apt-get install ntp, which is what I really wanted, and it worked great. I have network time. No idea why ping’s don’t work, and I don’t care right now… Everything I need is working.

    Thanks for putting up with me!

    Robert

  21. make (of qemu) gave:
    In file included from /home/john/Software/RaspberryPi/qemu-1.0/linux-user/syscall.c:3325:
    /home/john/Software/RaspberryPi/qemu-1.0/linux-user/ioctls.h:187: error: ‘SNDCTL_DSP_MAPINBUF’ undeclared here (not in a function)
    /home/john/Software/RaspberryPi/qemu-1.0/linux-user/ioctls.h:188: error: ‘SNDCTL_DSP_MAPOUTBUF’ undeclared here (not in a function)
    /home/john/Software/RaspberryPi/qemu-1.0/linux-user/ioctls.h:243: error: ‘SOUND_MIXER_ACCESS’ undeclared here (not in a function)
    make[1]: *** [syscall.o] Error 1
    make: *** [subdir-arm-linux-user] Error 2

  22. @ John Rose
    I recommend you follow the newer instructions @ http://www.cnx-software.com/2012/03/08/how-to-build-qemu-system-arm-in-linux/ and use linaro qemu.

    For your issue:
    A google search indicates that SNDCTL_DSP_MAPINBUF is defined in a file called include/linux/soundcard.h
    In debian/ubuntu, running apt-get search soundcard.h show that you can install libc6-dev to make sure this file is installed, you may try.

    sudo apt-get install libc6-dev

    The problem could also be because you have not install an arm-linux toolchain, e.g. in Debian/Ubuntu sudo apt-get install gcc-arm-linux-gnueabi

  23. libc6-dev is already the newest version

    but E: Couldn’t find package gcc-arm-linux-gnueabi

    Where is it?

    In new instructions, make -j 2 gave same problem.

  24. @ John Rose
    That’s weird, you should be able to install the arm toolchain as explained in http://www.cnx-software.com/2011/03/28/installing-linaro-arm-cross-toolchain-on-ubuntu/

    You can edit /home/john/Software/RaspberryPi/qemu-1.0/linux-user/ioctls.h, and check if there is a line that looks like:
    #include

    Do the build complains about this file at any stage? If it is not there, you could try to add it. Also check if /usr/include/linux/soundcard.h is present in your computer, and if it is, check the CFLAGS used when you build qemu, i.e you could type: export CFLAGS=-I/usr/include

  25. @ John Rose
    One more thing. Since you are using Ubuntu, why don’t you try to install qemu-system-arm directly instead of building it:

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

  26. @ cnxsoft
    Thanks for help. I installed qemu-system as per your instructions. I also did sudo apt-get upgrade and it upgraded python-debian & some qemu packages (e.g. qemu-user). I’m now lost as to what to do next. Currently, I have Qemulator 0.5 & Qemu Launcher 1.7.4 GUI apps available. Do I use them them or do I start somewhere else in your instructions?

  27. I checked on qemu-system-arm:
    john@JohnDesktop:~$ qemu-system-arm –version
    QEMU emulator version 1.0.50 (Debian 1.0.50-2012.03-0ubuntu1~ppa10.04.1), Copyright (c) 2003-2008 Fabrice Bellard

    I’ve tried running Qemulator 0.5 using a debian .img (in Terminal mode). It gives “Flash image must be given with the ‘pflash’ parameter” in qemu-system-arm window.

    Any ideas please?

  28. @ John Rose
    Are you using the Debian image provided by Raspberry Pi ?

    Then you’d better follow the instructions provided at http://www.cnx-software.com/2012/02/18/raspberry-pi-releases-1st-sd-card-image-debian-how-to-use-it-in-the-emulator

    Or even more simple, you can just download the kernel http://dl.dropbox.com/u/45842273/zImage and run:

    qemu-system-arm -M versatilepb -cpu arm1176 -m 256 -hda your_debian_image.img -kernel zImage -append “root=/dev/sda2” -serial stdio -redir tcp:2222::22

    I never used Qemulator or Qemu Launcher.

  29. I’d prefer to use a Debian Armel with lxde/xfce 6.0.4 for which I have the .iso. Is it possible to use that with QEMU?

  30. It’s not straightforward with getting, say, Debian Armel installed. I don’t fully understand why but it’s to with the initial boot of the installer. I’ve found out how to install Debian Armel Standard & Desktop and that’s explained very well (together with the necessary downloads) at
    http://people.debian.org/~aurel32/qemu/armel/

  31. I’ve just received the following email:

    Subject: Raspberry Pi Emulator w/ OpenGL ES support

    Message Body:
    I noticed that the emulation for the Raspberry PI that is recommended is out of date and completely lacks OpenGL ES support. There is a possibility to easily create an emulated image for use on qtonpi that makes use of this, and all it takes is modifying the maego/meego qemu instructions a little bit. Although, this image will not require the broadcom specific image for Opengl, and when you go to the actual hardware you haft to take that into account.

    anyways, the instructions for Qemu on ubuntu are extremely old. Qemu 0.15.50 completely lacks armv6 support, and the current version is 1.1.

    Meego Wiki – SDK/Qemu ( See “Building Qemu” section for incomplete instructions )
    http://wiki.meego.com/SDK/Qemu

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