asus predator remote debubing setup

as i life away from that laptop I setup a remote debugging setup:
the plan:
- Asus Tinkerboard 2: emulate a usb keyboard and usb stick to boot from using it’s gadget capable USB type C port/controller. and a simple usb camera to see the monitor
- Minestorms EV3 with one motor and a few lego pieces: mechanically press the power button (as that cant be done from a usb keyboard)

log

i found out https://ev3dev.org exists.
- a (VERY OLD) Debian Linux you can flash onto a sd card, plug into the Minestorms EV3 and have a normal linux on it.
Setting up mass storage USB Gadget on Tinkerboard 2
pic of the setup: Pasted image 20260710215442.png
discord messages: Pasted image 20260710215338.png … Pasted image 20260710215429.png
all camera apps i tried running through ssh -Y segfaulted… xD Pasted image 20260710222732.png
- thx OBS … Pasted image 20260709115112.png
- thx cheese (gnome webcam tool) … Pasted image 20260709115254.png

usbip detour

i wanted to usbip forward the usb camera to my local machine. (in heinseit stupid idea as it would work so terribly cause of bandwith limitations) the tinker os does not have usbip-core and usbip-host kernel modules :facepalm:

found my kernel source: https://github.com/TinkerBoard-Linux/rockchip-linux-kernel/commit/b8521caa5c7d78fb0e959c4260e6bbef09d8feac

actually managed to build two .ko files that worked… using this default.nix inside that source

let
pkgs = import <nixpkgs> { crossSystem = "aarch64-linux"; };
out = pkgs.linuxKernel.kernels.linux_5_10.overrideAttrs (prev: {
	src = ./src;
	modDirVersion = "5.10.209";
  configurePhase = ''
	make ARCH=arm64 defconfig
  '';

  buildPhase = ''
    make ARCH=arm64 M=drivers/usb/usbip modules
  '';

  installPhase = ''
    mkdir -p $out/
    cp drivers/usb/usbip/*.ko $out/
  '';
});

in out

(nixpkgs/917fec990948658ef1ccd07cef2a1ef060786846) (or smth like that. cant fully remember)

when opening the usb camera locally: Pasted image 20260710222355.png :dang: (Pasted image 20260710222425.png)

actually getting the cam to work

Pasted image 20260709183726.png finally got a picture
- with v4l2-ctl -d /dev/video5 --stream-mmap --stream-count=1 --stream-to=output.jpg

Google Search Ai was with three prompts able to give me

ssh root@localhost -p 2222 "ffmpeg -f v4l2 -input_format mjpeg -video_size 1280x720 -i /dev/video5 -c:v mpeg2video -b:v 3M -f mpegts pipe:1" | ffplay -fflags nobuffer -flags low_delay -i pipe:0

and that just works!!!!

v4l2-ctl --list-devices to find out which /dev/video

controlling the ev motor

https://www.ev3dev.org/docs/tutorials/tacho-motors/

back to story

first time turning the laptop on: Pasted image 20260710223444.png
the first debug messages i wanted to add (Pasted image 20260710224336.png, drivers/firmware/efi/libstub/x86-stub.c) resulted in an Illegal Instruction (Pasted image 20260710224508.png) … WTF???
- so onto debugging that with lldb which turned out to be quite a challenge… see: debugging the efi stub of the linux kernel
lldb crashed because $TMP does not exist if you do direnv of a nix-shell … Pasted image 20260711100233.png
that Illegal Instruction: we were jmp to 0x00000 because the efi_system_table was NULL
- no wonder… i should have put me efi_puts() after this line… xD
```
efi_system_table = sys_table_arg;
```

efi hello world

(using edk2)

used their devcontainer.json (the build tooling is toooooo all over the place, to manage to get smth up with a simple nix shell… in a resonable time)
- so cloned https://github.com/tianocore/edk2 and opened it in the devcontainer
./Conf/target.txt

ACTIVE_PLATFORM       = EmulatorPkg/EmulatorPkg.dsc
TARGET                = DEBUG
TARGET_ARCH           = X64
TOOL_CHAIN_CONF       = Conf/tools_def.txt
TOOL_CHAIN_TAG        = GCC
BUILD_RULE_CONF = Conf/build_rule.txt

make -C BaseTools
source edksetup.sh
build -m MdeModulePkg/Application/HelloWorld/HelloWorld.inf
and I will just edit: ./MdeModulePkg/Application/HelloWorld/HelloWorld.c
- error galore, when I tried to use an external EfiApp.inf file…

intellisence

the build system has support to generate a compile_commands.json … https://github.com/tianocore/edk2/blob/927c7b1d819fed9fa718a793f5da3b376dd6eacc/BaseTools/Source/Python/build/BuildReport.py#L2298
so we use: build -m MdeModulePkg/Application/HelloWorld/HelloWorld.inf -Y COMPILE_INFO
- our compile_commands then at smth like: /workspaces/edk-app/edk2/Build/EmulatorX64/DEBUG_GCC/CompileInfo/compile_commands.json
- for zed we do like: ^88e86b … with the right path
NICE!!

lldb for the efi shell

(lldb) target create edk2/Build/Shell/DEBUG_GCC/X64/ShellPkg/Application/Shell/Shell/DEBUG/Shell.dll -s edk2/Build/Shell/DEBUG_GCC/X64/ShellPkg/Application/Shell/Shell/DEBUG/Shell.debug
- the Shell.dll is actually an elf file

modifying the efi shell to add telnet

the older v1.0 efi shell had a telnet server aparently … https://github.com/tianocore/edk-Shell/blob/master/TelnetMgmt/TelnetMgmt.c#L230
some efi shell doc: UEFI_Shell_2_2.pdf
yay, tcp connect: Pasted image 20260711221247.png

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