BeagleBone Black with Upstream Software

BeagleBone Black with Upstream Software

• 1.
  BeagleBone Black with upstreamsoftware Viktoriia Taraniuk
• 2.
  BBB Overview Open hardware: ●Technical Reference Manual (TRM) ● Schematic and PCB Supported in upstream: ● Kernel ● U-boot Cost: $55
• 3.
  Software components ● U-Boot ●Kernel ● Busybox
• 4.
  Building the software
• 5.
  Rules of thegame ● Do all steps in one terminal ● Always check your path ● Don’t put / in the beginning of path because you can damage your rootfs ● Don’t work with root rights unless it was mentioned ● Each command should be verified (esp. export command)
• 6.
  Toolchains ● Main components: ○Cross-compiler, linker, etc (gcc, ld, as, cpp) ○ libc (and other related libraries) ○ debugger (GDB), binary tools ● There are two kinds of toolchains: ○ Baremetal: for building programs being run without OS ○ Linux: for building user-space programs being run under Linux OS
• 7.
  Baremetal toolchain ● Downloadbaremetal toolchain: gcc-linaro-7.2.1-2017.11-x86_64_arm-eabi.tar.xz https://releases.linaro.org/components/toolchain/binaries/latest-7/arm-eabi/ ● Extract toolchain to /opt: $ sudo tar xJvf gcc-linaro-7.2.1-2017.11-x86_64_arm-eabi.tar.xz -C /opt/
• 8.
  Linux toolchain ● Downloadlinux toolchain: gcc-linaro-7.2.1-2017.11-x86_64_arm-linux-gnueabihf.tar.xz https://releases.linaro.org/components/toolchain/binaries/latest-7/arm-linux-gnueabihf/ ● Extract toolchain to /opt: $ sudo tar xJvf gcc-linaro-7.2.1-2017.11-x86_64_arm-linux-gnueabihf.tar.xz -C /opt/
• 9.
  U-Boot: Obtain ● ObtainU-Boot source code: $ git clone git://git.denx.de/u-boot.git ● Checkout to latest release tag: $ git checkout v2018.03
• 10.
  U-Boot: Build ● Configuretoolchain environment in shell: $ export PATH=/opt/gcc-linaro-7.2.1-2017.11-x86_64_arm-eabi/bin:$PATH $ export CROSS_COMPILE=arm-eabi- $ export ARCH=arm ● Build U-Boot: $ make am335x_boneblack_defconfig $ make -j4
• 11.
  Linux kernel: Obtain ●Install host build dependencies: $ sudo apt-get install ncurses-dev libssl-dev bc bison flex ● Obtain Linux kernel source code: $ git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
• 12.
  Linux kernel: Configure ●Configure toolchain environment in shell: $ export PATH=/opt/gcc-linaro-7.2.1-2017.11-x86_64_arm-eabi/bin:$PATH $ export CROSS_COMPILE=arm-eabi- $ export ARCH=arm ● Generate .config: $ make multi_v7_defconfig
• 13.
  Linux kernel: Build ●Build kernel image and device tree blob: $ make -j4 zImage am335x-boneblack.dtb
• 14.
  Busybox: Obtain ● Obtainsources: $ git clone git://busybox.net/busybox.git ● Setup build environment (use Linux toolchain): $ export ARCH=arm $ export PATH=/opt/gcc-linaro-7.2.1-2017.11-x86_64_arm-linux-gnueabihf/bin:$PATH $ export CROSS_COMPILE=arm-linux-gnueabihf- ● Checkout to latest stable branch: $ git checkout 1_28_stable
• 15.
  Linking: static vsdynamic ● Static linking: libc (.a) is compiled in your binary ○ Only “busybox” binary is needed in rootfs ○ Easier to build and minimal ○ Some networking functions won’t work (nslookup, see libnss) ● Dynamic linking: libc used as a shared library (.so) ○ Only one copy of libc is used (both in rootfs and in RAM) ○ Dynamic libraries must be copied in rootfs /lib (libc and its dependencies)
• 16.
  Busybox: Build andinstall ● Configure BusyBox with all features: $ make defconfig $ make menuconfig ● Build BusyBox: $ make -j4 ● Install to _install/ dir: $ make install
• 17.
  Creating rootfs
• 18.
  Populate root dir ●Create root directories: $ mkdir -p _install/{boot,dev,etc/init.d,proc,root,sys,tmp} ● Make “init” link: $ cd _install/ $ ln -s bin/busybox init $ cd -
• 19.
  Init script ● Createinit script (_install/etc/init.d/rcS): #!/bin/sh mount -t sysfs none /sys mount -t proc none /proc echo /sbin/mdev > /proc/sys/kernel/hotplug mdev -s ● Make script executable: $ chmod +x _install/etc/init.d/rcS
• 20.
  Populate /boot ● Populate/boot dir with kernel files: $ cd _install/boot $ cp $WORK_DIR/linux/arch/arm/boot/zImage . $ cp $WORK_DIR/linux/arch/arm/boot/dts/am335x-boneblack.dtb . $ cd -
• 21.
  Resulting rootfs / ├── bin │└── busybox ├── boot │ ├── am335x-boneblack.dtb │ └── zImage ├── dev ├── etc │ └── init.d │ └── rcS ├── init -> bin/busybox ├── linuxrc -> bin/busybox ├── proc ├── root ├── sbin ├── sys ├── tmp └── usr ├── bin └── sbin
• 22.
  Q&A Thank you!