matthewcroughan: https://github.com/NixOS/nixpkgs/pull/453557/commits/f3b1b7752116a278b0d9e63b956cb44b832941fa
@Sigmanificient has managed to make the musl build work, and forcing the musl version of the package still has a succeeding test:

diff --git a/nixos/tests/login-nosuid.nix b/nixos/tests/login-nosuid.nix
index cdd14478d02c..7f6242294fe0 100644
--- a/nixos/tests/login-nosuid.nix
+++ b/nixos/tests/login-nosuid.nix
@@ -21,6 +21,8 @@
       security.enableWrappers = false;
       security.pwaccess.enable = true;
 
+      security.pwaccess.package = pkgs.pkgsMusl.pwaccess;
+
       environment.systemPackages = [ pkgs.which ];
 
       # pam debug without giant rebuild

So, you may be able to just take that whole PR, set security.pwaccess.enable = true; and security.enableWrappers = false;, and then have suid-less login!

Trying to cross compile the linux kernel with clang, finding that for some reason pkgsCross.aarch64-multiplatform.buildPackages.clang does not not have arm_neon.h. Looks like for some reason it's set up to just use --gcc-toolchain= pointing to the aarch64 gcc toolchain, which in my experience always runs into these incompatible header issues. The build finds this one, but it seems some of the types are messed up when it's used for clang. I've always been baffled by clang's intent to be a cross-compiler, but always being so difficult :(

Would appreciate if anyone has any suggestions on how to approach these kinds of problems.