From 3e9decc557f1372afbaf6010d831c3333357bd00 Mon Sep 17 00:00:00 2001
From: Alyssa Ross <hi@alyssa.is>
Date: Sun, 18 Apr 2021 11:10:42 +0000
Subject: [PATCH 1/3] netbsd.cksum: init at 8.0

We need the source directory of this package for config(1), so we
might as well just package it.
---
 pkgs/os-specific/bsd/netbsd/default.nix | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/pkgs/os-specific/bsd/netbsd/default.nix b/pkgs/os-specific/bsd/netbsd/default.nix
index 910e5044c59..26d4685cbfc 100644
--- a/pkgs/os-specific/bsd/netbsd/default.nix
+++ b/pkgs/os-specific/bsd/netbsd/default.nix
@@ -386,6 +386,13 @@ let
     sha256 = "00a3zmh15pg4vx6hz0kaa5mi8d2b1sj4h512d7p6wbvxq6mznwcn";
     NIX_CFLAGS_COMPILE = lib.optional stdenv.isLinux "-DNO_BASE64";
   };
+
+  cksum = mkDerivation {
+    path = "usr.bin/cksum";
+    version = "8.0";
+    sha256 = "0327820171djn9dzb2q1arypxw2zsxiixnd1ahy34dagd9cwcphj";
+    meta.platforms = lib.platforms.netbsd;
+  };
   ##
   ## END COMMAND LINE TOOLS
   ##

From 37ac32a351f3ce93bd731e9fbf5f54f1c37829f1 Mon Sep 17 00:00:00 2001
From: Alyssa Ross <hi@alyssa.is>
Date: Sun, 18 Apr 2021 11:13:22 +0000
Subject: [PATCH 2/3] netbsd.config: init at 8.0

Needed to build the NetBSD kernel.
---
 pkgs/os-specific/bsd/netbsd/default.nix | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/pkgs/os-specific/bsd/netbsd/default.nix b/pkgs/os-specific/bsd/netbsd/default.nix
index 26d4685cbfc..c94f00f4782 100644
--- a/pkgs/os-specific/bsd/netbsd/default.nix
+++ b/pkgs/os-specific/bsd/netbsd/default.nix
@@ -393,6 +393,16 @@ let
     sha256 = "0327820171djn9dzb2q1arypxw2zsxiixnd1ahy34dagd9cwcphj";
     meta.platforms = lib.platforms.netbsd;
   };
+
+  config = mkDerivation {
+    path = "usr.bin/config";
+    version = "8.0";
+    sha256 = "0piyn8lgdqxwz9wkgc2plzp2xpj93fs4xncri8l0jfas9rv5j2m5";
+    NIX_CFLAGS_COMPILE = [ "-DMAKE_BOOTSTRAP" ];
+    buildInputs = [ compat ];
+    nativeBuildInputs = [ makeMinimal install mandoc byacc flex ];
+    extraPaths = [ cksum.src ];
+  };
   ##
   ## END COMMAND LINE TOOLS
   ##

From ddcb48cc3d176bae330a3d9fd0dfcc4038f1085b Mon Sep 17 00:00:00 2001
From: Alyssa Ross <hi@alyssa.is>
Date: Sun, 18 Apr 2021 16:53:11 +0000
Subject: [PATCH 3/3] netbsd.sys: actually build the kernel

Before, we were only building the headers, firmware, and bootloader.

CONFIG could be overridden to use another pre-defined kernel, but
there's no way to pass a custom kernel configuration yet.

Tested booting the built kernel in a NetBSD VM.
---
 pkgs/os-specific/bsd/netbsd/default.nix | 29 ++++++++++++++++++++++---
 1 file changed, 26 insertions(+), 3 deletions(-)

diff --git a/pkgs/os-specific/bsd/netbsd/default.nix b/pkgs/os-specific/bsd/netbsd/default.nix
index c94f00f4782..112a70917cf 100644
--- a/pkgs/os-specific/bsd/netbsd/default.nix
+++ b/pkgs/os-specific/bsd/netbsd/default.nix
@@ -433,12 +433,35 @@ let
     path = "sys";
     version = "8.0";
     sha256 = "123ilg8fqmp69bw6bs6nh98fpi1v2n9lamrzar61p27ji6sj7g0w";
+
+    CONFIG = "GENERIC";
+
     propagatedBuildInputs = [ include ];
-    nativeBuildInputs = [ makeMinimal install tsort lorder statHook uudecode ];
+    nativeBuildInputs = [
+      makeMinimal install tsort lorder statHook uudecode config genassym
+    ];
+
+    postConfigure = ''
+      pushd arch/$MACHINE/conf
+      config $CONFIG
+      popd
+    '';
+
+    makeFlags = [ "FIRMWAREDIR=$(out)/libdata/firmware" ];
+    hardeningDisable = [ "pic" ];
+    MKKMOD = "no";
+    NIX_CFLAGS_COMPILE = [ "-Wa,--no-warn" ];
+
+    postBuild = ''
+      make -C arch/$MACHINE/compile/$CONFIG $makeFlags
+    '';
+
+    postInstall = ''
+      cp arch/$MACHINE/compile/$CONFIG/netbsd $out
+    '';
+
     meta.platforms = lib.platforms.netbsd;
     extraPaths = [ common.src ];
-    MKKMOD = "no";
-    makeFlags = [ "FIRMWAREDIR=$(out)/libdata/firmware" ];
   };
 
   headers = symlinkJoin {