117 lines
4.0 KiB
Markdown
117 lines
4.0 KiB
Markdown
---
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layout: arm
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title: How to configure Qemu
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---
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## Target Pi on Mac
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So even the idea is to run software on the Pi, not everyone has a Pi (yet :-)
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Others, like me, prefer to develop on a laptop and not carry the Pi around.
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For all those, this here explains how to emulate the Pi on a Mac.
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Even if you have a Pi, [this explains](/remote_pi.html) a nice way to develop with it.
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### Replace the buggy llvm
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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.
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So type gcc -v and if the output contains "LLVM version 5.1", you must install gcc4.2. Easily done with homebrew:
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brew install https://raw.github.com/Homebrew/homebrew-dupes/master/apple-gcc42.rb
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This will not interfere with the systems compiler as the gcc4.2 has postfixed executables (ie gcc-4.2)
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### Qemu
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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".
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brew install qemu --env=std --cc=gcc-4.2
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For people not on Maverick it may work without the -cc option.
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### Pi images
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Create a directory for the stuff on your mac, ie pi.
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Get the latest Raspian image.
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There seems to be some chicken and egg problem, so quemu needs the kernel seperately. There is one in the links.
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### Configure
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In the blog post there is some fun configuration, I did it and it works. Not sure what happens if you don't.
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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:
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nano /etc/ld.so.preload
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Put a # in front of the first to comment it out. Should just be one line there.
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Press ctrl-x then y then enter to save and exit.
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(Optional) Create a file /etc/udev/rules.d/90-qemu.rules with the following content:
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KERNEL=="sda", SYMLINK+="mmcblk0"
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KERNEL=="sda?", SYMLINK+="mmcblk0p%n"
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KERNEL=="sda2", SYMLINK+="root"
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The kernel sees the disk as /dev/sda, while a real pi sees /dev/mmcblk0.
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This will create symlinks to be more consistent with the real pi.
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### Boot
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There is quite a bit to the command line to boot the pi (i have an alias), here it is:
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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
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- the cpu is what braodcom precifies, ok
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- memory is unfortuantely hardcoded in the versatilepb "machine"
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- the kernel is the file name of the kernel you downloaded (or extracted)
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- raspbian.img is the image you downloaded. Renamed as it probably had the datestamp on it
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- the redir redircts the port 2222 to let you log into the pi
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So
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ssh -p 2222 -l pi localhost
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will get you "in". Ie username pi (password raspberry is the default) and port 2222
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Qemu bridges the network (that it emulates), and so your pi is now as connected as your mac.
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### More Disk
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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.
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dd if=/dev/zero bs=1m count=2048 >> raspbian.img
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The 2048 gets you 2Gb as we specified 1m (meg).
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On the pi launch
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sudo fdisk /dev/sda
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This will probably only work if your do the (Optional) config above.
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Say p, and write down the start of the second partition (122880 for me).
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d 2 will delete the second partition
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n p 2 will create a new primary second partition
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write the number as start and just return to the end.
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p to check
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w to write and quit.
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Reboot, and run
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resize2fs
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Links
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-----
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Blog post: [http://xecdesign.com/qemu-emulating-raspberry-pi-the-easy-way/](http://xecdesign.com/qemu-emulating-raspberry-pi-the-easy-way/)
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Kernel: [http://xecdesign.com/downloads/linux-qemu/kernel-qemu](http://xecdesign.com/downloads/linux-qemu/kernel-qemu)
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Rasbian file system(preferably be torrent): [http://www.raspberrypi.org/downloads/](http://www.raspberrypi.org/downloads/)
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