Minaduki-Shigure / BeagleBone_Proj

This is a repo for the practice of the lecture "Digital System II". It mainly contains the general steps of running a Linux and adding a few functions to the system on a TI BeagleBone Black.

My migration

Step 1: Install the cross compilers

First mission is to install the gcc for arm linux to ensure that we can compile the kernel.
As using Ubuntu distribution of Linux, use apt to install gcc-arm-linux-gnueabihf and the libraries used.

$ sudo apt install gcc-arm-linux-gnueabihf

After finished installing, compile a simple "Hello world" program to see if the compiler is working properly.

$ arm-linux-gnueabigf-gcc -o helloarm helloworld.c

Use file to see the properties of the output file.

helloarm: ELF 32-bit LSB pie executable, ARM, EABI5 version 1 (SYSV), dynamically linked, interpreter /lib/ld-linux-armhf.so.3, BuildID[sha1]=8e92a4ef2b70e3db73ce9fe6a740a9025be3fdfc, for GNU/Linux 3.2.0, not stripped

Step 2: Configure the Makefile of the kernel

Apply the defualt configure file for BeagleBone.

$ make bb.org_defconfig ARCH=arm

Then use make menuconfig ARCH=arm to manage the modules.

1. In Device Drivers, enter the entry of Block devices and enable RAM block device support.
2. In File systems, enable support for Network File Systems.
3. Save the new configuration as .config.

Step 3: Compile the kernel

$ make ARCH=arm CROSS_COMPILE=<Your own cross compiler prefix> -j8
## -j8 means use 8 threads to compile

In ths case, my Cross compiler prefix is set as arm-linux-gnueabihf-.
The image file output is located at ./arch/arm/boot/.
The Device tree binary file output is located at ./arch/arm/boot/dts/.

Step 4: Build the busybox for Beaglebone

1. Download the busybox source. In this case, we use apt-src to get the source code.

$ apt-src install busybox

Remember not to run apt-src as root, or you may have to manually chown the source file downloaded.

2. Configure the busybox using make menuconfig.

1. Enable the option Build static binary (no shared libs).
2. Set Cross compiler prefix as arm-linux-gnueabihf-.
3. (Optional) Set the destination for make install, you can found the built binaries there.
4. (Optional) Remove some of the components if you want the binaries to be smaller.

3. make and make install to generate the binaries.

The busybox is now ready to deploy. We are going to use it in the following steps.

Step 5: Prepare files for the file system.

1. Make a new folder named as fs_root (This name is not fixed, use your own if you'd like).
2. Copy all the files generated by busybox to the new folder.
3. Move to the new folder and mkdir etc.
4. In the directory etc, create the following files:

1. inittab

# /etc/inittab
::sysinit:/etc/init.d/rcS
::askfirst:-/bin/sh
::once:/usr/sbin/telnetd -l /bin/login
::ctrlaltdel:/sbin/reboot
::shutdown:/bin/umount -a -r

2. rc

Remember: This file needs to be excutable, do not forget to chmod +x.

#!/bin/sh
hostname Minaduki-BeagleBone
mount -t proc proc /proc
/bin/cat /etc/motd

3. motd (Message Of ToDay)

#  .88b  d88. d888888b d8b   db  .d8b.  d8888b. db    db db   dD d888888b
#  88'YbdP`88   `88'   888o  88 d8' `8b 88  `8D 88    88 88 ,8P'   `88'
#  88  88  88    88    88V8o 88 88ooo88 88   88 88    88 88,8P      88
#  88  88  88    88    88 V8o88 88~~~88 88   88 88    88 88`8b      88
#  88  88  88   .88.   88  V888 88   88 88  .8D 88b  d88 88 `88.   .88.
#  YP  YP  YP Y888888P VP   V8P YP   YP Y8888D' ~Y8888P' YP   YD Y888888P
# ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
#                Linux 4.4.155 on BeagleBone Black am335x.
#       Powered by MINADUKI Technologies 2019. All rights reserved.
# ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

5. Make a dir named init.d and inside the dir, make a symbol link from etc/init.d/rcS to etc/rc. This assign the file etc/rc to be the startup script excuted by inittab.

$ mkdir init.d
$ cd init.d
$ ln -s ../rc rcS

6. Make a dir named dev, inside the dir create necessary devices using mknod.

$ sudo mknod console c 5 1
$ sudo mknod null c 1 3
$ sudo mknod zero c 1 5

Tips: Tired of typing sudo? You may use sudo chmod +s to make the excutable always run as root.

7. Create empty dirs proc and sys for processes and SYSFS file system.
8. Create dir lib, copy the following libraries from the cross compilers to the dir lib:

ld-2.30.so
libc-2.30.so
libm-2.30.so
The version of the libraries may vary, so you may have to change it to your own version.

9. Make symbol links for the libraries.

$ ln -s ld-2.30.so ld-linux-armhf.so.3
$ ln -s libc-2.30.so libc.so.6
$ ln -s libm-2.30.so libm.so.6

That's all for the files. Your fs_root dir shall now look like this:

total 40
drwxr-xr-x 10 minaduki minaduki 4096 11月 12 15:50 .
drwxr-xr-x  7 minaduki minaduki 4096 11月 12 15:09 ..
drwxr-xr-x  2 minaduki minaduki 4096 11月 12 15:04 bin
drwxr-xr-x  2 minaduki minaduki 4096 11月 12 15:42 dev
drwxr-xr-x  3 minaduki minaduki 4096 11月 12 15:26 etc
drwxr-xr-x  2 minaduki minaduki 4096 11月 12 15:53 lib
lrwxrwxrwx  1 minaduki minaduki   11 11月 12 15:11 linuxrc -> bin/busybox
drwxr-xr-x  2 minaduki minaduki 4096 11月 12 15:50 proc
drwxr-xr-x  2 minaduki minaduki 4096 11月 12 15:04 sbin
drwxr-xr-x  2 minaduki minaduki 4096 11月 12 15:50 sys
drwxr-xr-x  4 minaduki minaduki 4096 11月 12 15:04 usr

Step 6: Initialize the file system image

We use the ramdisk as an example, but you can choose other media as your root file system.

1. Make an image file, my image is 8 MiB in size.

$ dd if=/dev/zero of=ramdisk_img bs=1k count=8192
$ mke2fs ramdisk_img

2. Mount the ramdisk.

$ mount ramdisk_img ~/Desktop/mnt

3. To save the space on ramdisk, we use strip to remove symbols in the libraries, making them taking up less space.

$ arm-linux-gnueabihf-strip ld-2.30.so
$ arm-linux-gnueabihf-strip libc-2.30.so
$ arm-linux-gnueabihf-strip libm-2.30.so

4. Copy the files generated above to the ramdisk.

Unfortunately, we made a mistake above, the device files under dev cannot be copied, so we have to redo the mknod in the ramdisk mounted.

5. Umount the ramdisk and compress the file to save space.

$ umount ~/Desktop/mnt
$ gzip ramdisk_img

You may now boot with the new ramdisk.

Step 7: Configure minicom for serial communication

Remeber to configure as superuser
For the first time running minicom, use command minicom -s to configure.

1. Enter serial port setup.
2. Set /dev/ttyUSB0 as the Serial Device.
3. Set Bps/Par/Bits to be 115200 8N1.
4. Disable all Flow Controls.
   
   After finished, save the setup as defualt and run minicom.

Step 8: Start the tftp service on PC.

1. Use apt to install package tftp-hpa and tftpd-hpa.
2. Edit /etc/hosts.allow and add:

tftpd:ALL
in.tftpd:ALL

3. (Optional) (For Manjaro) Edit /etc/conf.d/tftpd to modify the default workspace.
4. (Optional) (For Ubuntu) Edit /etc/default/tftpd-hpa to modify the default workspace.
5. (Optional) Use chmod to edit the permissions of the workspace.
6. Start the service.

$ systemctl start tftpd.socket tftpd.service
$ systemctl enable tftpd.socket

Step 9: Try to boot with U-boot using the kernel image and the ramdisk

Wait for the device to boot into U-boot and use the following script to boot.

U-Boot# set ipaddr 192.168.208.121 # IP addr of BeagleBone
U-Boot# set serverip 192.168.208.48 # IP addr of PC

U-Boot# tftp 0x82000000 zImage # image file
U-Boot# tftp 0x88080000 ramdisk_img.gz # ramdisk
U-Boot# tftp 0x88000000 am335x-boneblack.dtb # device tree

U-Boot# set ramdisk root=/dev/ram rw initrd=0x88080000
U-Boot# set bootargs console=ttyO0,115200 $ramdisk
U-Boot# bootz 0x82000000 0x88080000: <size of ramdisk> 0x88000000

Step 10: Configure the network on Beaglebone

1. Configure the IP address using ifconfig command. The default name of the network interface is eth0.
2. Configure the gateway, the gateway of our lab is 192.168.208.254.

$ ifconfig eth0 192.168.208.121
$ route add default gw 192.168.208.254

Step 11: Start the NFS service on PC

1. Use apt to install nfs-kernel-server.
2. Edit the file /etc/exports to configure the service.
3. Use systemctl to start and enable the service.

You may use exportfs -a to refresh the NFS directories.
Be adviced that we found sometimes systemctl may fail to start NFS, try to use service then.

Step 12: Mount the NFS on Beaglebone

$ mkdir mnt
$ mount 192.168.208.48:/srv/nfs4 mnt -o nolock,proto=tcp

(Optional) Step 13: Boot via NFS

Now that we have comfirmed the NFS works properly, why not try something interesting?

1. Edit the file /etc/exports to add our new dir to NFS service. The file shall now look like this:

/srv/nfs4 *(rw,sync,no_subtree_check,no_root_squash)
/srv/nfs4/nfsboot_rootfs *(rw,sync,no_subtree_check,no_root_squash)

2. Use exportfs to refresh the NFS configure of the host.
3. Now try to boot via NFS:

U-Boot# set ipaddr 192.168.208.121 # IP addr of BeagleBone
U-Boot# set serverip 192.168.208.48 # IP addr of PC

U-Boot# tftp 0x82000000 zImage # image file
U-Boot# tftp 0x88000000 am335x-boneblack.dtb # device tree

U-Boot# setenv rootfs root=/dev/nfs rw nfsroot=<server_ip>:<Root_Dir>
U-Boot# setenv nfsaddrs nfsaddrs=<ip>:<server_ip>:<gateway>:<mask>
U-Boot# setenv bootargs console=ttyS0,115200 $rootfs $nfsaddrs
U-Boot# bootz 0x82000000 - 0x88000000

In my example, my input looks like this:

U-Boot# set ipaddr 192.168.208.121 # IP addr of BeagleBone
U-Boot# set serverip 192.168.208.35 # IP addr of PC

U-Boot# tftp 0x82000000 zImage # image file
U-Boot# tftp 0x88000000 am335x-boneblack.dtb # device tree

U-Boot# setenv rootfs root=/dev/nfs rw nfsroot=192.168.208.35:/srv/nfs4/nfsboot_rootfs,vers=3
U-Boot# setenv nfsaddrs nfsaddrs=192.168.208.121:192.168.208.35:192.168.208.254:255.255.255.0
U-Boot# setenv bootargs console=ttyS0,115200 $rootfs $nfsaddrs
U-Boot# bootz 0x82000000 - 0x88000000

Attention please:
The kernel I use (and provide) will use NFSv2 as default, if you are using later versions of NFS server, add ,vers=3(using NFSv3) or ,vers=4(using NFSv4) at the end of the nfsroot argument. Be advised that some of the NFSv4 servers defaultly refuses udp connections, if you do not want to modify your NFS server, you may add ,proto=tcp to force the client to use tcp to connect.

If failed when trying to mount the NFS, you may add nfsrootdebug when setting bootargs, it will let the kernel print the DEBUG log and you may be able to analyze it to find your mistakes.

Step 14: IO drivers

Be careful! The command echo writes 2 bytes (including enter) but our driver is only expecting 1.

(Unfinished)Step 14: Setup GDBserver on the BeagleBone

1. Download gdb from the Internet, move in to dir gdbserver and run configure:

$ ./configure --target=arm-linux --host=x86-linux

2. Make the program.

Step 15: Display via frame buffer

1. Perparing: When compiling your kernel, enable Device Drivers->Graphics support->DRM support for TI LCDC Display Controller and Device Drivers->Graphics support->I2C encoder or helper chips->NXP semiconductors TDA668X HDMI encoder.

Remember to pay attention to your memory! If your fbp pointer is a int there might be not enough memory!

When your screen displays "No Signal"...
This requires you mount sysfs in advance, add the following content to your etc/rc

mount -t sysfs sys /sys

Then run the following commands:

# cd /sys/class/graphics/fb0
# echo "Whatever you like" > blank

How to capture the screen:
Use the following commands to capture your screen:

$ cat /dev/fb0 > demo.raw

And you may convert it via ffmpeg:

$ ffmpeg -vcodec rawvideo -f rawvideo -pix_fmt rgb565 -s 1280X1024 -i demo.raw -f image2 -vcodec png out-%d.png

Step 16: Migrate Mplayer

1. Use apt-src or wget to get mplayer, zlib and libmad. Recompile the kernel and make sure the sound drivers are included.
2. Deploy libmad:

$ ./configure --enable-fpm=arm --host=arm-linux-gnueabihf --enable-speed --prefix=/home/minaduki/Desktop/Beaglebone_Proj/mplayer/install/libmad CC=arm-linux-gnueabihf-gcc

The gcc for arm-linux do not accept the option '-fforce-mem', edit the Makefile generated, delete -fforce-mem from CFLAGS.

$ make
$ make install

2. Deploy zlib:

$ CC=arm-linux-gnueabihf-gcc ./configure --prefix=/home/minaduki/Desktop/Beaglebone_Proj/mplayer/install/glib
$ make
$ make install

3. Deploy alsa-lib:

$ ./configure --host=arm-linux-gnueabihf --target=arm-linux --prefix=/home/minaduki/Desktop/Beaglebone_Proj/mplayer/install/alsa-lib --enable-shared --disable-python
 
or?

$ ./configure --host=arm-linux-gnueabihf --target=arm-linux --prefix=/home/minaduki/Desktop/Beaglebone_Proj/mplayer/install/alsa-lib --enable-static --disable-python --disable-shared

./configure --host=arm-linux-gnueabihf --target=arm-linux --prefix=/home/minaduki/Desktop/Beaglebone_Proj/mplayer/install/alsa-lib --enable-static=yes --disable-python --enable-shared=no


$ make
$ make install

Then copy the libraries to the rootfs.

4. Deploy MPlayer: MPlayer requires source of ffmpeg and will clone it from github.com, since the lightning-like speed, we may clone from gitee.com in advance.

$ git clone https://gitee.com/mirrors/ffmpeg.git

Configure & Make:

$ ./configure --cc=arm-linux-gnueabihf-gcc --target=arm-linux-gnueabihf --enable-static --prefix=/home/minaduki/Desktop/Beaglebone_Proj/mplayer/install/mplayer --disable-dvdread --enable-fbdev --disable-mencoder --disable-live --enable-mad --disable-armv5te --disable-armv6 --enable-cross-compile --extra-cflags="-I/home/minaduki/Desktop/Beaglebone_Proj/mplayer/install/libmad/include -I/home/minaduki/Desktop/Beaglebone_Proj/mplayer/install/glib/include" --extra-ldflags="-L/home/minaduki/Desktop/Beaglebone_Proj/mplayer/install/libmad/lib -L/home/minaduki/Desktop/Beaglebone_Proj/mplayer/install/glib/lib"

Whatever library is missing, just copy that f**king library into the rootfs.

CC=arm-linux-gnueabi-gcc ./configure --disable-fpm --host=arm-linux-gnueabi --enable-speed --prefix=/home/minaduki/Desktop/nfsroot/nfs4/pi0/mplayer/install/libmad

CC=arm-linux-gnueabi-gcc ./configure --prefix=/home/minaduki/Desktop/nfsroot/nfs4/pi0/mplayer/install/glib

./configure --prefix=/home/minaduki/Desktop/nfsroot/nfs4/pi0/mplayer/install/mplayer --cc=arm-linux-gnueabi-gcc --target=arm-linux-gnueabi --enable-fbdev --disable-mencoder --disable-live --enable-mad --enable-cross-compile --extra-cflags="-I/home/minaduki/Desktop/nfsroot/nfs4/pi0/mplayer/install/libmad/include -I/home/minaduki/Desktop/nfsroot/nfs4/pi0/mplayer/install/glib/include" --extra-ldflags="-L/home/minaduki/Desktop/nfsroot/nfs4/pi0/mplayer/install/libmad/lib -L/home/minaduki/Desktop/nfsroot/nfs4/pi0/mplayer/install/glib/lib"

CC=arm-linux-gnueabihf-gcc ./configure --disable-fpm --host=arm-linux-gnueabihf --enable-speed --prefix=/home/minaduki/Desktop/nfsroot/nfs4/pi0/mplayer/install/libmad

CC=arm-linux-gnueabihf-gcc ./configure --prefix=/home/minaduki/Desktop/nfsroot/nfs4/pi0/mplayer/install/glib

./configure --prefix=/home/minaduki/Desktop/nfsroot/nfs4/pi0/mplayer/install/mplayer --cc=arm-linux-gnueabihf-gcc --target=arm-linux-gnueabihf --enable-fbdev --disable-mencoder --disable-live --enable-mad --enable-cross-compile --extra-cflags="-I/home/minaduki/Desktop/nfsroot/nfs4/pi0/mplayer/install/libmad/include -I/home/minaduki/Desktop/nfsroot/nfs4/pi0/mplayer/install/glib/include" --extra-ldflags="-L/home/minaduki/Desktop/nfsroot/nfs4/pi0/mplayer/install/libmad/lib -L/home/minaduki/Desktop/nfsroot/nfs4/pi0/mplayer/install/glib/lib"

Touch screen

1. enable in kernel: Device Drivers → Input device support → Touchscreens → USB Touchscreen Driver