Tweak 04

Dependencies

• [2] 5LP7FPFX Fix CI
• [3] EGQ4SEV5 Add demo for 04
• [*] W2MX3YW4 Add CMake and cross example

Change contents

• edit in 04-cmake-and-cross/flake.nix at line 26
  [5.4591]

  [3.701]
  + # The 'default' package is the package injected into our package set
• edit in 04-cmake-and-cross/flake.nix at line 28
  [3.747]

  [5.4895]
  + # But the package set also has a pkgsCross set, and we can select our package from one of its contents

  + packages.cross-riscv64 = pkgs.pkgsCross.riscv64.wttr-delft;
• replacement in 04-cmake-and-cross/demo.sh at line 15
  [3.1100]→[3.1100:1214](∅→∅)
  − , Packaging in this way and making use of the sandboxed Nix build process can hepl find missing dependencies etc.
  [3.1100]

  [3.1214]
  + , Packaging in this way and making use of the sandboxed Nix build process

  + , can help find dependencies that were not correctly declared etc.
• edit in 04-cmake-and-cross/demo.sh at line 33
  [3.1610]

  [3.1610]
  + , The previous build was for x86_64-linux by default because that is our current system:

  + x "${file_cmd}" ./result/bin/wttr-delft
• replacement in 04-cmake-and-cross/demo.sh at line 36
  [3.1611]→[3.1611:1658](∅→∅)
  − , We can very easily set up cross-compilation.
  [3.1611]

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  + h We can very easily set up cross-compilation.
• replacement in 04-cmake-and-cross/demo.sh at line 40
  [3.1785]→[3.1785:1833](∅→∅)
  − , If we take a look at what the flake provides:
  [3.1785]

  [3.1833]
  + , Now we can call a different output:

  + x nix build "${dir}#cross-riscv64"

  + , And this is indeed a RISC-V binary:

  + x "${file_cmd}" ./result/bin/wttr-delft

  +

  + h Emulation

  + , If we take a look at what the flake provides we see multiple architectures as well:
• replacement in 04-cmake-and-cross/demo.sh at line 49
  [3.1860]→[3.1860:1949](∅→∅),[3.1949]→[2.104:144](∅→∅)
  − h The previous build was for x86_64-linux by default because that is our current system:

  − x "${file_cmd}" ./result/bin/wttr-delft
  [3.1860]

  [3.1980]
  + n This will not work if the emulation is not available:

  + , But, if you use NixOS it\'s also very simple to set up binfmt to emulate e.g. aarch64-linux!
• edit in 04-cmake-and-cross/demo.sh at line 52
  [3.1981]→[3.1981:2052](∅→∅)
  − h But we can easily build for aarch64-linux \(e.g. for Raspberry Pi\):
• edit in 04-cmake-and-cross/demo.sh at line 55
  [3.2139]→[3.2139:2234](∅→∅),[3.2234]→[2.186:187](∅→∅)
  − n If you use NixOS it\'s also very simple to set up binfmt to still be able to run the binary!

  −