While reading the build system sources, I noticed it also uses vendored Jasper. We might want to use the Fedora patch to unbundle it or better find a way to disable it since Jasper is full of security holes.

Cross-building works for the most part, but I found some iregularitues with shebangs, eg.

$ nix-build . -A pkgsCross.aarch64-multiplatform.netpbm
$ head result-bin/bin/ppmquant                                                               
#! /nix/store/j206pskg2yzyla1cnfrb9kb5n5bfvjgm-bash-4.4-p23/bin/bash -e

Otherwise, nicely done 👍

Could you clarify what the irregularities are?

Of course. After cross building from x86 to aarch64, the shebang should point to an aarch64 version of bash, otherwise the script would probably run into an exec error.
The bash it points to however is the one of the build system

$ file /nix/store/j206pskg2yzyla1cnfrb9kb5n5bfvjgm-bash-4.4-p23/bin/bash
/nix/store/j206pskg2yzyla1cnfrb9kb5n5bfvjgm-bash-4.4-p23/bin/bash: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /nix/store/2pi6zgkwnr3zdslvlv16nixpzvbyjx1n-glibc-2.31/lib/ld-linux-x86-64.so.2, for GNU/Linux 2.6.32, not stripped

Weird. I would expect the patchShebangsAuto hook to do the right thing wrt cross compilation. OR is the wrapProgram causing the issue?

It looks like patchShebang does the wrong thing here as the bash reference is already a reference to the Nix store.
This would probably be worth fixing at that level.

A practical solution (not necessarily pretty) would be to just patch it over like so.

@GrahamcOfBorg build netpbm pkgsCross.aarch64-multiplatform.netpbm

@Ericson2314 @matthewbauer any idea how to make makeWrapper use the correct shell for shebang?

@jtojnar yeah I recently learned that makeWrapper is set up wrong. it should use targetPackages.runtimeShellso we usedepsBuildBuildvsnativeBuildInputsto control what shell is used. Instead people have been putting it inbuildInputs` to achieve the same result which isn't right when its only a build-time dep.

I should make an issue for this.