From b2793a2ce2d84df536db13dc40fb145ed4dba6c3 Mon Sep 17 00:00:00 2001
From: Sam Lantinga <[EMAIL REDACTED]>
Date: Tue, 14 Jan 2025 12:58:30 -0800
Subject: [PATCH] Removed obsolete Raspberry Pi documentation
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docs/README-raspberrypi.md | 188 -------------------------------------
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-Raspberry Pi
-============
-
-Requirements:
-
-Raspberry Pi OS (other Linux distros may work as well).
-
-In modern times, the Raspberry Pi works mostly like any other Linux device:
-for video, you can use X11, Wayland, or KMSDRM. For audio, you can use ALSA,
-PulseAudio, or PipeWire, etc. OpenGL, OpenGL ES, and Vulkan are known to work.
-
-There is a video backend in SDL called "rpi" that uses a deprecated Broadcom
-interface (named "dispmanx") to draw directly to the console without X11.
-Newer Raspberry Pi OS releases don't support this (and work fine with our
-"kmsdrm" backend for the same purposes, a standard Linux interface). Don't
-panic if you can't use this backend, or CMake says it can't find libraries it
-needs for this.
-
-SDL has, in past times, worked on the original Raspberry Pi and the RPi 2, but
-these devices are no longer targets we actively test; if they broke, please
-report bugs or send patches!
-
-The Raspberry Pi 3 and later (in 32-bit and 64-bit mode) are still known to
-work well at the time of this writing. The Raspberry Pi Zero and Zero 2 are
-also known to work well.
-
-
-## Documentation Out Of Date
-
-The rest of this document is likely out of date; a lot has changed in recent
-years in both SDL and the Raspberry Pi universe, and this document has not
-been updated to reflect those details. Take the rest of this information with
-a grain of salt!
-
-
-
-NEON
-----
-
-If your Pi has NEON support, make sure you add -mfpu=neon to your CFLAGS so
-that SDL will select some otherwise-disabled highly-optimized code. The
-original Pi and Pi Zero units don't have NEON; everything from the Pi2/PiZero2
-and later do.
-
-
-Cross compiling from x86 Linux
-------------------------------
-
-To cross compile SDL for Raspbian from your desktop machine, you'll need a
-Raspbian system root and the cross compilation tools. We'll assume these tools
-will be placed in /opt/rpi-tools
-
- sudo git clone --depth 1 https://github.com/raspberrypi/tools /opt/rpi-tools
-
-You'll also need a Raspbian binary image.
-Get it from: http://downloads.raspberrypi.org/raspbian_latest
-After unzipping, you'll get file with a name like: "<date>-wheezy-raspbian.img"
-Let's assume the sysroot will be built in /opt/rpi-sysroot.
-
- export SYSROOT=/opt/rpi-sysroot
- sudo kpartx -a -v <path_to_raspbian_image>.img
- sudo mount -o loop /dev/mapper/loop0p2 /mnt
- sudo cp -r /mnt $SYSROOT
- sudo apt-get install qemu binfmt-support qemu-user-static
- sudo cp /usr/bin/qemu-arm-static $SYSROOT/usr/bin
- sudo mount --bind /dev $SYSROOT/dev
- sudo mount --bind /proc $SYSROOT/proc
- sudo mount --bind /sys $SYSROOT/sys
-
-Now, before chrooting into the ARM sysroot, you'll need to apply a workaround,
-edit $SYSROOT/etc/ld.so.preload and comment out all lines in it.
-
- sudo chroot $SYSROOT
- apt-get install libudev-dev libasound2-dev libdbus-1-dev libraspberrypi0 libraspberrypi-bin libraspberrypi-dev libx11-dev libxext-dev libxrandr-dev libxcursor-dev libxi-dev libxss-dev
- exit
- sudo umount $SYSROOT/dev
- sudo umount $SYSROOT/proc
- sudo umount $SYSROOT/sys
- sudo umount /mnt
-
-There's one more fix required, as the libdl.so symlink uses an absolute path
-which doesn't quite work in our setup.
-
- sudo rm -rf $SYSROOT/usr/lib/arm-linux-gnueabihf/libdl.so
- sudo ln -s ../../../lib/arm-linux-gnueabihf/libdl.so.2 $SYSROOT/usr/lib/arm-linux-gnueabihf/libdl.so
-
-The final step is compiling SDL itself.
-
- export CC="/opt/rpi-tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian/bin/arm-linux-gnueabihf-gcc --sysroot=$SYSROOT -I$SYSROOT/opt/vc/include -I$SYSROOT/usr/include -I$SYSROOT/opt/vc/include/interface/vcos/pthreads -I$SYSROOT/opt/vc/include/interface/vmcs_host/linux"
- cd <SDL SOURCE>
- mkdir -p build;cd build
- LDFLAGS="-L$SYSROOT/opt/vc/lib" ../configure --with-sysroot=$SYSROOT --host=arm-raspberry-linux-gnueabihf --prefix=$PWD/rpi-sdl3-installed --disable-pulseaudio --disable-esd
- make
- make install
-
-To be able to deploy this to /usr/local in the Raspbian system you need to fix up a few paths:
-
- perl -w -pi -e "s#$PWD/rpi-sdl3-installed#/usr/local#g;" ./rpi-sdl3-installed/lib/libSDL3.la ./rpi-sdl3-installed/lib/pkgconfig/sdl3.pc
-
-Apps don't work or poor video/audio performance
------------------------------------------------
-
-If you get sound problems, buffer underruns, etc, run "sudo rpi-update" to
-update the RPi's firmware. Note that doing so will fix these problems, but it
-will also render the CMA - Dynamic Memory Split functionality useless.
-
-Also, by default the Raspbian distro configures the GPU RAM at 64MB, this is too
-low in general, specially if a 1080p TV is hooked up.
-
-See here how to configure this setting: http://elinux.org/RPiconfig
-
-Using a fixed gpu_mem=128 is the best option (specially if you updated the
-firmware, using CMA probably won't work, at least it's the current case).
-
-No input
---------
-
-Make sure you belong to the "input" group.
-
- sudo usermod -aG input `whoami`
-
-No HDMI Audio
--------------
-
-If you notice that ALSA works but there's no audio over HDMI, try adding:
-
- hdmi_drive=2
-
-to your config.txt file and reboot.
-
-Reference: http://www.raspberrypi.org/phpBB3/viewtopic.php?t=5062
-
-Text Input API support
-----------------------
-
-The Text Input API is supported, with translation of scan codes done via the
-kernel symbol tables. For this to work, SDL needs access to a valid console.
-If you notice there's no SDL_EVENT_TEXT_INPUT message being emitted, double check that
-your app has read access to one of the following:
-
-* /proc/self/fd/0
-* /dev/tty
-* /dev/tty[0...6]
-* /dev/vc/0
-* /dev/console
-
-This is usually not a problem if you run from the physical terminal (as opposed
-to running from a pseudo terminal, such as via SSH). If running from a PTS, a
-quick workaround is to run your app as root or add yourself to the tty group,
-then re-login to the system.
-
- sudo usermod -aG tty `whoami`
-
-The keyboard layout used by SDL is the same as the one the kernel uses.
-To configure the layout on Raspbian:
-
- sudo dpkg-reconfigure keyboard-configuration
-
-To configure the locale, which controls which keys are interpreted as letters,
-this determining the CAPS LOCK behavior:
-
- sudo dpkg-reconfigure locales
-
-
-OpenGL problems
----------------
-
-If you have desktop OpenGL headers installed at build time in your RPi or cross
-compilation environment, support for it will be built in. However, the chipset
-does not actually have support for it, which causes issues in certain SDL apps
-since the presence of OpenGL support supersedes the ES/ES2 variants.
-The workaround is to disable OpenGL at configuration time:
-
- ./configure --disable-video-opengl
-
-Or if the application uses the Render functions, you can use the SDL_RENDER_DRIVER
-environment variable:
-
- export SDL_RENDER_DRIVER=opengles2
-
-Notes
------
-
-* When launching apps remotely (via SSH), SDL can prevent local keystrokes from
- leaking into the console only if it has root privileges. Launching apps locally
- does not suffer from this issue.
-
-