DISCLAIMER: this is an old post from 2018 that I've republished for historical reference, as I saw a few sites link back to it. There is now a coordinated effort to support running Debian on Raspberry Pi, complete with pre-built images: see https://raspi.debian.net/ for details!
In summer 2018, I ordered a Raspberry Pi 3 Model B+. This model, new at the time, released in March 2018 and came with a higher clock speed, as well as upgraded Ethernet, Wi-Fi, and Bluetooth capabilities over its immediate predecessor.
I decided I wanted to install Debian on my Pi and use it as a potential ARM build box. Although doing so is not as well supported as an official Raspbian release, this custom build gave me the ability to track the rolling release Debian testing (useful for development) and run a 64-bit system.
I based my setup off of the unofficial Debian image for the Raspberry Pi 3 over at https://wiki.debian.org/RaspberryPi3. Because this image targets the original Pi 3 and not the Model B+, some additional tweaks are needed to get the system working. After extracting the image to my SD card and expanding the root partition via GParted, here's roughly the preparations I made:
The first problem was an outdated firmware version - this can be fixed
by copying newer versions start\*.elf fixup\*.dat bootcode.bin bcm2710-rpi-3-b-plus.dtb from the Raspberry Pi firmware
repository into the boot partition of the SD card. Then, set
device-tree in config.txt to use that .dtb: i.e.
device_tree=bcm2710-rpi-3-b-plus.dtb
The 4.14 kernel shipped in the Debian image unfortunately lacks support
for Ethernet - complete support for the LAN7515 chip used by the Model 3
B+ only landed in kernel 4.18, which is currently in RC. This
essentially leaves two kernel options for the RPi: a mainline 4.18
kernel or the official Raspberry Pi kernel built for arm64. In my
case, I actually started out with a 4.18 kernel before switching to the
RPi fork, since there are a few
components
(e.g. a cpufreq driver) that haven't been upstreamed yet. Both of these
options involve a bit of kernel compiling, since Linux 4.18 was not in
Debian as of writing. To cross compile an ARM64 kernel from my AMD64
Debian machine, you will need to install gcc-aarch64-linux-gnu
and build-essential (though this is not a complete list as other
build-deps may have already been on my machine).
After extracting or checking out the mainline kernel, use the arm64 default config:
cp arch/arm64/configs/defconfig .configUnlike with 32 bit ARM, there is only one generic default config for
ARM64 encompassing a variety of devices. Note: if you use a mainline
kernel, make sure to use the device tree blob shipped in mainline
Linux
arch/arm64/boot/dts/broadcom/**bcm2837-rpi-3-b-plus.dtb**
instead of the one in the raspberrypi/firmware repo
bcm2710-rpi-3-b-plus.dtb. Otherwise, you may get stuck at the
rainbow boot screen! The compile+install process is similar to that of
the RPi kernel (see below).
Although Raspbian does not use it, the Raspberry Pi kernel itself has supported 64-bit mode for quite some time. After checking out the sources:
make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- bcmrpi3_defconfigwill configure a kernel build for the RPi 3.
First, mount the two SD card partitions on your machine; in this
example, I used /mnt/boot for the first (boot) partition and
/mnt/ext4 for the second (root) partition.
# Build
make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu-
# Install
sudo make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- INSTALL_MOD_PATH=/mnt/ext4 modules_install
# You can replace kernel.img with a more descriptive name:
# e.g. I used something like raspberrypi-kernel_1.20180417-1_arm64.img
# for the RPi kernel
sudo cp arch/arm64/boot/Image /mnt/boot/kernel.img
sudo cp arch/arm64/boot/dts/broadcom/*.dtb /mnt/boot/
# For the RPi kernel, also install the following:
sudo cp arch/arm64/boot/dts/overlays/*.dtb* /mnt/boot/overlays/
sudo cp arch/arm64/boot/dts/overlays/README /mnt/boot/overlays/Now, edit your config.txt to point to your new kernel (and keep
a backup of it in case it gets overwritten!)
At this point, I could boot my Pi and have its console fill up the TV I had plugged it into.
USB, HDMI video, and Ethernet just about worked out of the box, though I
had a minor issue with the default firewall provided in the Debian image
(the -m comment module for iptables didn't autoload with my custom
kernel). Because I was running a custom kernel at this point, I had to
purge Debian's raspi3-firmware since it automatically updates /
overwrites config.txt to point to the Debian kernel on updates.
Once Linux 4.18+ makes its way into Debian, this should no longer be
necessary. (I also elected to remove the Debian kernel image since it
wasn't being used)
dtparams=audio=on to
config.txt/lib/firmware/brcm/, since Debian does not ship it in its firmware-brcm80211 package.
(Raspbian's fork of the package does though!)startx and crashing a few seconds later. dmesg
showed me errors like
vc4: Failed to allocate from CMA", which I fixed by
adding cma=256M to cmdline.txtNow I have a Pi running Debian in working condition!? Anything not mentioned in this article (Bluetooth, GPIO, etc.) has not been tested yet.