flake: use nixpkgs-unstable to build u-boot

flake.lock

@@ -18,11 +18,27 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1700390070,
-        "narHash": "sha256-de9KYi8rSJpqvBfNwscWdalIJXPo8NjdIZcEJum1mH0=",
+        "lastModified": 1701053011,
+        "narHash": "sha256-8QQ7rFbKFqgKgLoaXVJRh7Ik5LtI3pyBBCfOnNOGkF0=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "e4ad989506ec7d71f7302cc3067abd82730a4beb",
+        "rev": "5b528f99f73c4fad127118a8c1126b5e003b01a9",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-23.05",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "nixpkgs-unstable": {
+      "locked": {
+        "lastModified": 1700794826,
+        "narHash": "sha256-RyJTnTNKhO0yqRpDISk03I/4A67/dp96YRxc86YOPgU=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "5a09cb4b393d58f9ed0d9ca1555016a8543c2ac8",
         "type": "github"
       },
       "original": {
@@ -32,24 +48,12 @@
         "type": "github"
       }
     },
-    "nixpkgs_2": {
-      "locked": {
-        "lastModified": 1697730408,
-        "narHash": "sha256-Ww//zzukdTrwTrCUkaJA/NsaLEfUfQpWZXBdXBYfhak=",
-        "owner": "NixOS",
-        "repo": "nixpkgs",
-        "rev": "ff0a5a776b56e0ca32d47a4a47695452ec7f7d80",
-        "type": "github"
-      },
-      "original": {
-        "id": "nixpkgs",
-        "type": "indirect"
-      }
-    },
     "not-os": {
       "inputs": {
         "firmware": "firmware",
-        "nixpkgs": "nixpkgs_2"
+        "nixpkgs": [
+          "nixpkgs"
+        ]
       },
       "locked": {
         "lastModified": 1699416673,
@@ -68,6 +72,7 @@
     "root": {
       "inputs": {
         "nixpkgs": "nixpkgs",
+        "nixpkgs-unstable": "nixpkgs-unstable",
         "not-os": "not-os"
       }
     }

flake.nix

@@ -1,12 +1,16 @@
 {
   description = "Not-OS port to the Zynq-7000 platform";
   
-  inputs.nixpkgs.url = github:NixOS/nixpkgs/nixos-unstable;
+  inputs.nixpkgs.url = github:NixOS/nixpkgs/nixos-23.05;
+  inputs.nixpkgs-unstable.url = "github:NixOS/nixpkgs/nixos-unstable";
   inputs.not-os.url = github:cleverca22/not-os;
+  inputs.not-os.inputs.nixpkgs.follows = "nixpkgs";
   
-  outputs = { self, nixpkgs, not-os }:
+  outputs = { self, nixpkgs, nixpkgs-unstable, not-os }:
     let
       pkgs = import nixpkgs { system = "x86_64-linux"; };
+      # To be used for building u-boot.
+      pkgs-unstable = import nixpkgs-unstable { system = "x86_64-linux"; };
 
       gnu-platform = "arm-none-eabi";
 
@@ -174,7 +178,9 @@
         dontFixup = true;
       };
 
-      u-boot = pkgs.pkgsCross.armv7l-hf-multiplatform.buildUBoot {   
+      # U-boot needs the recent patch in master to fix cross-compile issues.
+      # See https://github.com/NixOS/nixpkgs/pull/265411.
+      u-boot = pkgs-unstable.pkgsCross.armv7l-hf-multiplatform.buildUBoot {
         defconfig = "xilinx_zynq_virt_defconfig";
         preConfigure = ''
           export DEVICE_TREE=zynq-zc706