Build a package for arm64 on amd64

snapcraft
1

I have a ubuntu 18.04-amd64 and my snapcraft version is 2.43.1+18.4.1. I want to cross-build snap for an arm64. My yaml files is as below:

name: helloworld
version: "1.0.0"
grade: stable
summary: Print 'Hello World' to console output
description: |
  This App is a simple example to show how to make an App.
base: core18
confinement: strict

architectures:
  - build-on: amd64
    run-on:arm64

# define how apps & services are exposed to host system
apps:
  HelloWorld:
    command: HelloWorld
    # interfaces to connect to https://snapcraft.io/docs/supported-interfaces
    plugs: [desktop, unity7, home, opengl, x11, wayland, gsettings]
    

#  describes how to import, and potentially build, each required part of the snap:
parts:
  helloworld:
    plugin: dump
    source: ./generated/build
    after: [libsgl]



  libsgl:
    plugin: nil
    stage-packages:
      # Here for the plugins-- they're not linked in automatically.
      - libx11-xcb1
      - libglu1-mesa
      - libxrender1
      - libxi6
      - libegl1-mesa
      - fontconfig
      - libgl1-mesa-dri
      - libxkbcommon0
      - ttf-ubuntu-font-family
      - dmz-cursor-theme
      - adwaita-icon-theme
      - gnome-themes-standard
      - shared-mime-info
      - libgdk-pixbuf2.0-0
      - libgtk2.0-0
      - xdg-user-dirs
      - libxrandr2
      - libwayland-cursor0
      - libwayland-egl1
      - libpq5

when I run snapcraft it creates an arm snap for me but during building it is downloading amd64 packages which seems it is wrong. would you please explain why does it happen?

2

while cross building is technically possible, it will require you to hack up your host system a lot to teach it to fully support arm64 packages first ā€¦

then you need to have a cross compiler and need to patch the build systems of all the sources you build to make sure they understand cross compiling if they do not already ā€¦ and indeed all your compiler environment variables need to be adjusted to point to the right places ā€¦

if you can not do your build with https://snapcraft.io/build or use snapcrafts remote-build feature:

iā€™d really recommend getting arm64 hardware to build on ā€¦ cross building anything that has actual library dependencies is extremely painful and fragile ā€¦

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