--author stef
--title egy noob naiv fanboikodasa az ephyr osrol
--date today
stef par har hete belecsuszott ebbe a covid19 contact tracing vilagba, vett 2 nrf51dk devboardot, is oruleteben kitalalta, hogy kiprobalja a regota toplay listajan veszteglo zephyr os-szel.  uj hw es uj os, what could possibly go wrong? valojaban semmi, ez olyan mint egy arduino, csak felnotteknek. "hihetetlen, valoszinuleg meg fogom banni ezt az egesz fanboikodast 2-3 ev mulva es szegyenkezni fogok emiatt, de most nagyon lelkes vagyok." - concludes stef
--newpage ?
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--newpage nsa
--heading ghost 2018-ban
  * 2018 linux security summit: https://www.youtube.com/watch?v=Jov4dTnjm2o

  * stef felirta toplay listajara... majd teltek az evek...

--newpage whiskey - tango - foxtrott 
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      UooU\.'@@@@@@`.
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--newpage WTF!
--heading WTF!

  * RTOS

  * Linux Foundation

  * Arches: x86, arm, arc, nios II, xtensa, riscv, posix/native, qemu!

  * 200+ boards

  * Vendors (intel, ti, nordic, nxp, adafruit, sifive, ...)

--newpage features
--heading features

  * host and controller bluetooth 5.0 stacks (e.g. hci-usb)
  * minimal libc (newlib)
  * tinycrypt
  * shell
  * ...

--newpage deps

git cmake ninja-build gperf ccache dfu-util device-tree-compiler wget
python3-dev python3-pip python3-setuptools python3-tk python3-wheel
xz-utils file make gcc gcc-multilib g++-multilib libsdl2-dev

pip3 install --user -U west

optional: https://github.com/zephyrproject-rtos/sdk-ng/releases/download/v0.11.3/zephyr-sdk-0.11.3-setup.run

--newpage westf
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--newpage west
--heading wtf west?
West was added to the Zephyr project to fulfill two fundamental requirements:

    * The ability to work with multiple Git repositories

    * The ability to provide an extensible and user-friendly command-line interface for basic Zephyr workflows

see more: https://docs.zephyrproject.org/latest/guides/west/why.html

--newpage
--heading fs structure of a typical project

--beginoutput
<home>/app
├── CMakeLists.txt
├── prj.conf
└── src
    └── main.c
--endoutput

more info at https://docs.zephyrproject.org/latest/application/index.html#source-tree-structure

--newpage Konfig
--heading prj.cfg
each project has a kernel style config

--beginoutput
CONFIG_BT=y
CONFIG_BT_BROADCASTER=y
CONFIG_BT_OBSERVER=y
CONFIG_BT_DEBUG_LOG=y
CONFIG_ENTROPY_DEVICE_RANDOM_GENERATOR=y
CONFIG_HARDWARE_DEVICE_CS_GENERATOR=y
CONFIG_TINYCRYPT=y
CONFIG_TINYCRYPT_SHA256_HMAC=y
CONFIG_TINYCRYPT_SHA256=y
CONFIG_SPI=y
CONFIG_SPI_1=y
CONFIG_DISK_ACCESS=y
CONFIG_DISK_ACCESS_SDHC=y
CONFIG_DISK_ACCESS_SPI_SDHC=y
CONFIG_LOG=y
CONFIG_FILE_SYSTEM=y
CONFIG_FAT_FILESYSTEM_ELM=y
CONFIG_GPIO=y
--endoutput

--newpage
--heading make menuconfig
--beginshelloutput
% west build -t menuconfig
--endshelloutput
---:
demo

--newpage device tree GPIOs
--heading device tree GPIOs
--beginoutput
buttons {
   compatible = "gpio-keys";
   button0: button_0 {
      gpios = <&gpio0 17 (GPIO_PULL_UP | GPIO_ACTIVE_LOW)>;
      label = "Push button switch 0";
   };
   button1: button_1 {
      gpios = <&gpio0 18 (GPIO_PULL_UP | GPIO_ACTIVE_LOW)>;
      label = "Push button switch 1";
   };
   button2: button_2 {
      gpios = <&gpio0 19 (GPIO_PULL_UP | GPIO_ACTIVE_LOW)>;
      label = "Push button switch 2";
   };
   button3: button_3 {
      gpios = <&gpio0 20 (GPIO_PULL_UP | GPIO_ACTIVE_LOW)>;
      label = "Push button switch 3";
   };
--endoutput

--newpage device tree SPI
--heading SPI device tree fragment
--beginoutput
&spi0 {
   /* Cannot be used together with i2c0. */
   /* status = "okay"; */
   sck-pin = <7>;
   mosi-pin = <29>;
   miso-pin = <30>;
};
--endoutput

--newpage device tree SDHC
--heading SD card over SPI
--beginoutput
&spi0 {
        status = "okay";
        cs-gpios = <&gpio0 0 GPIO_ACTIVE_HIGH>;

        sdhc0: sdhc@0 {
                compatible = "zephyr,mmc-spi-slot";
                reg = <0>;
                status = "okay";
                label = "SDHC0";
                spi-max-frequency = <16000000>;
        };
};
--endoutput
--newpage getting started
--heading getting started

--beginoutput
# for debian
% export CROSS_COMPILE=/usr/bin/arm-none-eabi-
% export ZEPHYR_TOOLCHAIN_VARIANT=cross-compile

# how own toolchain
% export GNUARMEMB_TOOLCHAIN_PATH=/home/s/tasks/tcn/nrf51/toolchain/arm
% export ZEPHYR_TOOLCHAIN_VARIANT=gnuarmemb

# for convenience
% export PATH=/home/s/tasks/tcn/nrf51/toolchain/arm/bin:$PATH
% source env/bin/activate

% west build -b nrf51dk_nrf51422 ctrace
--endoutput

--newpage demo
--heading demo
---:
  * show zbuild.log
---:
  * show some sources

--newpage last week
--heading dnet last week
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     (_/         ||
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      (____(____)
--newpage last week II
--heading stef
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   /# /_\_
  |  |/o\o\
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    (___)_)
--newpage last week III
--heading NCC Group
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    \
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    ^__^         /
    (oo)\_______/  _________
    (__)\       )=(  ____|_ \_____
        ||----w |  \ \     \_____ |
        ||     ||   ||           ||
--newpage last week IV
--heading stef
 ____________________________________________
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 \//  |    
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  \_|  o|  
  /\___/   
 /  ||||__ 
    (___)_)
--newpage :/
--heading bad news
https://research.nccgroup.com/2020/05/26/research-report-zephyr-and-mcuboot-security-assessment/

  * 24 vulns

  * limited resources -> limited mitigations

--newpage hardening
--heading hardening

--beginoutput
% ninja hardenconfig
% make hardenconfig
--endoutput

--beginoutput
CONFIG_BOOT_BANNER=n
CONFIG_STACK_CANARIES=y
CONFIG_STACK_POINTER_RANDOM=100
CONFIG_PRINTK=n
CONFIG_EARLY_CONSOLE=n
CONFIG_OVERRIDE_FRAME_POINTER_DEFAULT=y
CONFIG_LOG=n
CONFIG_BUILD_OUTPUT_STRIPPED=y
CONFIG_FAULT_DUMP=0
CONFIG_STACK_SENTINEL=y
--endoutput

--newpage conclusion
--heading conclusion

a zephyr os olyan mint az arduino sdk-ja, csak felnotteknek. elmeny vele dolgozni, de nem eroszakolja rad magat a butacska IDEjevel.

hobbyprojektre mindenkeppen melegen tudom ajanlani. profitermek fejlesztesre max ha nem szekurity szenzitiv egyelore, de ugy erzem ez a jovoben a megvaltozott figyelemmel lehet valtozni fog.