%hr/
%p
  layout: arm
  title: How to configure Qemu
  —
%h2#target-pi-on-mac Target Pi on Mac
%p So even the idea is to run software on the Pi, not everyone has a Pi (yet :-)
%p Others, like me, prefer to develop on a laptop and not carry the Pi around.
%p For all those, this here explains how to emulate the Pi on a Mac.
%p
  Even if you have a Pi,
  %a{:href => "/remote_pi.html"} this explains
  a nice way to develop with it.
%h3#replace-the-buggy-llvm Replace the buggy llvm
%p Written April 2014: as of writing the latest and greatest llvm based gcc (5.1) on Maverick (10.9) has a bug that makes qemu hang.
%p So type gcc -v and if the output contains “LLVM version 5.1”, you must install gcc4.2. Easily done with homebrew:
%pre
  %code
    :preserve
      brew install https://raw.github.com/Homebrew/homebrew-dupes/master/apple-gcc42.rb
%p This will not interfere with the systems compiler as the gcc4.2 has postfixed executables (ie gcc-4.2)
%h3#qemu Qemu
%p Then its time to get the Qemu. There may be other emulators out there, and i have read of armulator, but this is what i found discribed and it works and is “easy enough”.
%pre
  %code
    :preserve
      brew install qemu --env=std --cc=gcc-4.2
%p For people not on Maverick it may work without the -cc option.
%h3#pi-images Pi images
%p Create a directory for the stuff on your mac, ie pi.
%p Get the latest Raspian image.
%p There seems to be some chicken and egg problem, so quemu needs the kernel seperately. There is one in the links.
%h3#configure Configure
%p
  In the blog post there is some fun configuration, I did it and it works. Not sure what happens if you don’t.
  The booting is described below (you may or may not need an extra init=/bin/bash in the root… quotes), so boot your Pi and then configure:
%p nano /etc/ld.so.preload
%p Put a # in front of the first to comment it out. Should just be one line there.
%p Press ctrl-x then y then enter to save and exit.
%p (Optional) Create a file /etc/udev/rules.d/90-qemu.rules with the following content:
%pre
  %code
    :preserve
      KERNEL=="sda", SYMLINK+="mmcblk0"
      KERNEL=="sda?", SYMLINK+="mmcblk0p%n"
      KERNEL=="sda2", SYMLINK+="root"
%p
  The kernel sees the disk as /dev/sda, while a real pi sees /dev/mmcblk0.
  This will create symlinks to be more consistent with the real pi.
%h3#boot Boot
%p There is quite a bit to the command line to boot the pi (i have an alias), here it is:
%pre
  %code
    :preserve
      qemu-system-arm -kernel kernel-qemu -cpu arm1176 -m 256 -M versatilepb -no-reboot -serial stdio -append 'root=/dev/sda2 panic=1 rootfstype=ext4 rw' -hda raspbian.img -redir tcp:2222::22
%ul
  %li the cpu is what braodcom precifies, ok
  %li memory is unfortuantely hardcoded in the versatilepb “machine”
  %li the kernel is the file name of the kernel you downloaded (or extracted)
  %li raspbian.img is the image you downloaded. Renamed as it probably had the datestamp on it
  %li the redir redircts the port 2222 to let you log into the pi
%p So
%pre
  %code
    :preserve
      ssh -p 2222 -l pi localhost
%p will get you “in”. Ie username pi (password raspberry is the default) and port 2222
%p Qemu bridges the network (that it emulates), and so your pi is now as connected as your mac.
%h3#more-disk More Disk
%p The image that you download has only 200Mb free. Since the gcc is included and we’re developing (tiny little files of) ruby, this may be ok. If not there is a 3 step procedure to up the space.
%pre
  %code
    :preserve
      dd if=/dev/zero bs=1m count=2048 >> raspbian.img
%p The 2048 gets you 2Gb as we specified 1m (meg).
%p On the pi launch
%pre
  %code
    :preserve
      sudo fdisk /dev/sda
%p This will probably only work if your do the (Optional) config above.
%p
  Say p, and write down the start of the second partition (122880 for me).
  d 2 will delete the second partition
  n p 2 will create a new primary second partition
  write the number as start and just return to the end.
  p to check
  w to write and quit.
%p Reboot, and run
%pre
  %code
    :preserve
      resize2fs
%h2#links Links
%p
  Blog post:
  %a{:href => "http://xecdesign.com/qemu-emulating-raspberry-pi-the-easy-way/"} http://xecdesign.com/qemu-emulating-raspberry-pi-the-easy-way/
%p
  Kernel:
  %a{:href => "http://xecdesign.com/downloads/linux-qemu/kernel-qemu"} http://xecdesign.com/downloads/linux-qemu/kernel-qemu
%p
  Rasbian file system(preferably be torrent):
  %a{:href => "http://www.raspberrypi.org/downloads/"} http://www.raspberrypi.org/downloads/