====== Slackware ARM on the Raspberry Pi 2 ======

The Raspberry Pi 2 has a quad-core ARMv7 (Cortex-A7) 900MHz CPU and 1GB 450MHz LPDDR2 SDRAM. This revised and upgraded ARM single board computer supplants it's predecessor, the [[howtos:hardware:arm:raspberrypi|Raspberry Pi (1)]], and is considerably more powerful. Which is great for running Slackware ARM because every thing happens so much quicker and running/executing/compiling times are slashed dramatically in comparison.

The Raspberry Pi 2 is supported outside of the official Slackware ARM tree by the Slackware community.


=== Slackware releases 14.2, -current ===

Slackware ARM -current or Slackware ARM 14.2 can be installed on the Raspberry Pi 2.

Follow the link(s) in the table below. These are maintained by a separate author as part of the Slackware-on-Raspberry Pi community.

^ Site ^ Slackware versions ^ Using official Slackware packages ^ Installation methods ^ Notes ^
| [[https://sarpi.penthux.net/|SARPi Project]] | 14.2 | Yes | Slackware installer | An end-to-end HOW TO tutorial taking you through the installation and setup process. |

==== Manual install method without a Raspbian image ====

As long you use the most recent release of firmware [i.e. post-June 2019] and the latest Raspbian Buster image the [[howtos:hardware:arm:raspberrypi|Raspberry Pi 1 manual install method]] also works for the Pi 2.

This method is for installing Slackware ARM 14.2 on a Raspberry Pi 2 model B without a Raspbian image.
However, it should work for other Slackware ARM and Raspberry Pi versions.

=== 1. Partition and format the SD Card ===

<code>
$ sudo fdisk -l /dev/mmcblk0

Disk /dev/mmcblk0: 31.9 GB, 31914983424 bytes
4 heads, 16 sectors/track, 973968 cylinders, total 62333952 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

        Device Boot      Start         End      Blocks   Id  System
/dev/mmcblk0p1            2048       67583       32768    b  W95 FAT32
/dev/mmcblk0p2           67584    62333951    31133184   83  Linux
$ sudo mkfs.vfat /dev/mmcblk0p1
$ sudo mkfs.ext4 /dev/mmcblk0p2
</code>

Remarks:
  * I use a 32GB SD Card
  * I choose 32MB for the size of the first partition
  * I let the empty space left for the second partition

=== 2. Put the Raspberry Pi firmware in the SD Card ===

<code>
$ git clone https://github.com/raspberrypi/firmware.git
$ sudo mount /dev/mmcblk0p1 ~/mnt
$ sudo cp -r firmware/boot/* ~/mnt
$ sudo umount ~/mnt
$ sudo mount /dev/mmcblk0p2 ~/mnt
$ sudo mkdir -p ~/mnt/lib/modules
$ sudo cp -r firmware/modules/* ~/mnt/lib/modules
$ sudo umount ~/mnt
</code>

=== 3. Put the Slackware ARM mini root file system in the SD Card ===

<code>
$ wget -c ftp://ftp.arm.slackware.com/slackwarearm/slackwarearm-devtools/minirootfs/roots/slack-14.2-miniroot_01Jul16.tar.xz
$ sudo mount /dev/mmcblk0p2 ~/mnt
$ sudo tar -C ~/mnt -xf slack-14.2-miniroot_01Jul16.tar.xz
$ echo "/dev/mmcblk0p1 /boot vfat defaults 0 0" | sudo tee ~/mnt/etc/fstab
$ echo "/dev/mmcblk0p2 /     ext4 defaults 0 0" | sudo tee -a ~/mnt/etc/fstab
$ echo "proc           /proc proc defaults 0 0" | sudo tee -a ~/mnt/etc/fstab
$ PASSWD=$(openssl passwd -1 -salt cetkq/enZx6/c2 password)
$ sudo sed -i "s|\(root:\).*\(:16983:0:::::\)|\1${PASSWD}\2|" ~/mnt/etc/shadow
$ sudo sed -i 's|USE_DHCP\[1\]=""|USE_DHCP\[1\]="yes"|' ~/mnt/etc/rc.d/rc.inet1.conf
$ echo "PermitRootLogin yes" | sudo tee -a ~/mnt/etc/ssh/sshd_config
$ sudo umount ~/mnt
</code>

Remarks:
  * I set "password" as password for the "root" user
  * I set DHCP on the "eth1" network interface
  * I allow the "root" user to connect through SSH

=== 4. Insert the SD Card in the Raspberry Pi ===

Your SD Card is ready so you can insert it in the Raspberry Pi and boot.

You can connect remotely to your Raspberry Pi as "root" through SSH.
<code>
$ ssh root@raspberrypi
</code>

As soon as you are logged, you might want to install additional Slackware ARM packages:
<code>
$ wget --mirror ftp://ftp.arm.slackware.com/slackwarearm/slackwarearm-14.2
$ upgradepkg --install-new ftp.arm.slackware.com/slackwarearm/slackwarearm-14.2/slackware/*/*.txz
$ removepkg ftp.arm.slackware.com/slackwarearm/slackwarearm-14.2/slackware/*/kernel_*.txz
</code>

Remarks:
  * I consider that the Raspberry Pi hostname is "raspberrypi"
  * I recommend to add a normal user and use this user instead of "root"
  * I recommend to change the "root" user password
  * I recommend to disallow the "root" user to connect through SSH
  * I recommend to [[https://www.raspberrypi.org/documentation/linux/kernel/building.md|build your own Linux kernel]] packages because the kernel you are running does not match with the installed Slackware ARM packages

=== 5. Tips and tricks ===

== 5.1. Processor ==

The Raspberry Pi processor can reach 1.2GHz.
However, by default, it is stuck to 600MHz even if it is used at 100%.
You can check the current frequency of the processor by typing:
<code>$ cpufreq-info</code>

In order to reach 1.2GHz when the processor is used at 100% (i.e., use the frequency scaling), you need to change the default governors.
Add the following line to the end of the ''/etc/rc.d/rc.local'' file:
<code>echo ondemand | sudo tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor</code>
Now, the processor is correctly set.

== 5.2. Time ==

Unfortunately, the Raspberry Pi does not provide a Real-Time Clock (RTC).
That is why there is no battery included with the board.
It means that each time you shutdown the Raspberry Pi, the time is reset!
However, if you have internet access, you can update the time during the Slackware ARM boot.
Add the following line to the end of the ''/etc/rc.d/rc.local'' file:
<code>ntpdate pool.ntp.org</code>
Now, the time is correctly set.

== 5.3. Video ==

Unfortunately, the Raspberry Pi is not compatible with OpenGL (it is compatible OpenGL ES that is a subset of OpenGL).
It means that, by default, each application requiring OpenGL will be slow.
However, you can reach 60 FPS with OpenGL applications on the Raspberry Pi by using the correct driver.

Firstly, you need to build Mesa (>= 17.0.4) with the VC4 DRI driver:
<code>
$ CFLAGS="-O2 -march=armv8-a -mtune=cortex-a53 -mfloat-abi=softfp -mfpu=neon-vfpv4" \
	CXXFLAGS="-O2 -march=armv8-a -mtune=cortex-a53 -mfloat-abi=softfp -mfpu=neon-vfpv4" \
	./configure \
	--prefix=/usr \
	--sysconfdir=/etc \
	--with-dri-driverdir=/usr/lib/xorg/modules/dri \
	--with-egl-platforms=x11,drm \
	--with-gallium-drivers=vc4
$ make -j4
$ make install DESTDIR=/where/you/want/to/install
</code>
Then build your own Slackware ARM Mesa package and install it.

Secondly, add the following line to the end of the ''/boot/config.txt'' file:
<code>dtoverlay=vc4-fkms-v3d</code>
Then reboot the Raspberry Pi.

You can check that you are able to get 60 FPS with OpenGL applications on the Raspberry Pi by typing the following command in an X terminal:
<code>$ glxgears</code>

Now, the video is correctly set.
===== Sources =====

  * Originally written by [[wiki:user:exaga|Exaga]]
  * Contributions by [[wiki:user:yugiohjcj|yugiohjcj]]


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