ruby-x.github.io/app/views/pages/arm/qemu.html.haml
2018-04-28 18:32:42 +03:00

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= render "pages/arm/menu"
%h1= title "How to configure Qemu"
%h2 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,
=link_to "this explains", "remote_pi.html"
a nice way to develop with it.
%h3 Qemu
%p 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
%h3 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 qemu needs the kernel separately.
There is one in the links.
%h3 Configure
%p
In the blog post there is some fun configuration, I did it and it works.
Not sure what happens if you dont.
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
%pre
%code
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 broadcom specifies, ok
%li memory is unfortunately 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 were 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 (i used):
=ext_link "http://xecdesign.com/qemu-emulating-raspberry-pi-the-easy-way/", "http://xecdesign.com/qemu-emulating-raspberry-pi-the-easy-way/"
%p
More Recent post (i googled):
=ext_link "https://blog.agchapman.com/using-qemu-to-emulate-a-raspberry-pi/", "https://blog.agchapman.com/using-qemu-to-emulate-a-raspberry-pi/"
%p
Kernel:
=ext_link "http://xecdesign.com/downloads/linux-qemu/kernel-qemu", "http://xecdesign.com/downloads/linux-qemu/kernel-qemu"
%p
Rasbian file system(preferably by torrent):
=ext_link "http://www.raspberrypi.org/downloads/", "http://www.raspberrypi.org/downloads/"