125 lines
4.5 KiB
Plaintext
125 lines
4.5 KiB
Plaintext
= render "pages/arm/menu"
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%h1= title "How to configure Qemu"
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%h2 Target Pi on Mac or Linux
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%p So even the idea is to run software on the Pi, not everyone has a Pi (yet :-)
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%p Others, like me, prefer to develop on a laptop and not carry the Pi around.
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%p For all those, this here explains how to emulate the Pi on a unix.
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%p
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Even if you have a Pi,
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=link_to "this explains", "remote_pi.html"
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a nice way to develop with it.
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%p
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We'll more or less follow a
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=ext_link "blog post", "https://blog.agchapman.com/using-qemu-to-emulate-a-raspberry-pi/"
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i found, with small additions.
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%h3 Qemu
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%p
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Get the Qemu. There may be other emulators out there, and i have read of armulator,
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but this is what i found described and it works and is “easy enough”.
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%p
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On Mac:
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%pre
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%code
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brew install qemu
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On Linux with debian/ubuntu:
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%pre
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%code
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sudo apt-get qemu-system-arm
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%h3 Pi images
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%p
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Create a directory for the stuff on your computer, ie pi.
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%pre
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%code
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mkdir pi
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pi is in the gitignore, and the scripts in bin, will assume pi.
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%p
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Get the latest Raspian image. Currently (2019) the
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=ext_link "buster lite version" , "https://www.raspberrypi.org/downloads/raspbian/"
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without Gui is fine, and smaller.
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%p
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Change the file format with something like:
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%pre
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%code
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qemu-img convert -f raw -O qcow2 2019-07-10-raspbian-buster-lite.img raspbian-buster-lite.qcow
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So we can then resize the file, without it taking extra space (optional)
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%pre
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%code
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qemu-img resize raspbian-buster-lite.qcow +2G
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Put the resulting file into the pi directory. After booting you will need to change the
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partition to take the newly created space. This can be done with
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%pre
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%code
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sudo fdisk /dev/sda
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but for the buster image there is an extra little problem. A small free space is before
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the partition, but the new partion must be at the exact sector as the old. So copy the start
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sector before deleting the root partion and give fdisk the start sector when creatin the new.
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%p
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Also the file system has to be enlarged after another reboot:
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%pre
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%code
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sudo resize2fs /dev/sda2
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%h3 Kernel
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%p
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One still needs a kernel (even there is one on the image?), and Druv kindly keeps a
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repository of them. Since we downloaded the buster image, grab the
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=ext_link "buster kernel" , "https://github.com/dhruvvyas90/qemu-rpi-kernel/blob/master/kernel-qemu-4.19.50-buster"
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and also the mysterious
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=ext_link "dtb file." , "https://github.com/dhruvvyas90/qemu-rpi-kernel/blob/master/versatile-pb.dtb"
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Both go into the pi directory.
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%h3 Boot
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%p
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There is quite a bit to the command line to boot the pi. There is a script in the bin
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directory, but here it is:
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%pre
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%code
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:preserve
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qemu-system-arm -kernel pi/kernel-qemu-4.19.50-buster -dtb pi/versatile-pb.dtb -cpu arm1176 -m 256 -M versatilepb -no-reboot -serial stdio -append 'root=/dev/sda2 panic=1 rootfstype=ext4 rw' -hda pi/raspbian-buster-lite.qcow -net nic -net user,hostfwd=tcp::2222-:22
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%ul
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%li the cpu is what broadcom specifies, ok
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%li memory is unfortunately hardcoded in the versatilepb “machine”
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%li the kernel is the file name of the kernel you downloaded (or extracted)
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%li raspbian.img is the image you downloaded. Renamed as it probably had the datestamp on it
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%li the "-net user,hostfwd=tcp::2222-:22" redircts the port 2222 to let you log into the pi
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%p So (after the configuring the ssh, as shown below)
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%pre
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%code
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:preserve
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ssh -p 2222 -l pi localhost
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%p will get you “in”. Ie username pi (password raspberry is the default) and port 2222
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%p Qemu bridges the network (that it emulates), and so your pi is now as connected as your mac.
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%h3 Working on the pi
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%p
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You'll probably want to log in by ssh at some point. If for no other reason than
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Ctl-C will stop the emulator when you are logged in, and not the program you are
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running on the emulator. This gets old _really_ quickly.
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%p
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To configure the ssh server on the pi, log in and run
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%pre
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%code
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sudo raspi-config
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and enable ssh in the interface options.
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There is another text on how to
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=link_to "work on" , "/arm/remote_pi.html"
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the pi. Off course google is good , and raspian site can help too.
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%h2#links Links
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%ul#selector
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%li=ext_link "Post used for instructions", "https://blog.agchapman.com/using-qemu-to-emulate-a-raspberry-pi/"
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%li=ext_link "kernel repo" , "https://github.com/dhruvvyas90/qemu-rpi-kernel/"
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%li=ext_link "Rasbian image file", "http://www.raspberrypi.org/downloads/raspbian/"
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