linux: drop uImage support

Now that ARMv5 no longer uses `uImage`, there’s no point in keeping
around support for this deprecated format that the rest of the NixOS
infrastructure doesn’t handle. Modern U‐Boot setups should not
be affected in any way by this.

doc/release-notes/rl-2611.section.md

@@ -23,6 +23,8 @@
   `lib.systems.{examples,platforms}.{sheevaplug,pogoplug4}` have been unified into `lib.systems.examples.armv5tel-multiplatform`.
   Note that there is no official support for ARMv5 and it is not possible to build even a simple NixOS configuration out of the box.
 
+- Support for the legacy U‐Boot image format has been removed from the Linux kernel builders, as it is deprecated upstream and no longer used by any platform in Nixpkgs.
+
 - `requireFile` now sets `meta.license = lib.licenses.unfree` by default. Users of `requireFile`-based derivations that preserve this default will need to explicitly allow their evaluation as described in [](#sec-allow-unfree).
 
 - `librest` providing 0.7 ABI was removed. `librest_1_0` providing 1.0 ABI was renamed to `librest` and `librest_1_0` was kept as an alias.

pkgs/os-specific/linux/kernel/build.nix

@@ -19,7 +19,6 @@
   zlib,
   pahole,
   kmod,
-  ubootTools,
   fetchpatch,
   rustc-unwrapped,
   rust-bindgen-unwrapped,
@@ -116,31 +115,6 @@ lib.makeOverridable (
         ;
     };
 
-    # Folding in `ubootTools` in the default nativeBuildInputs is problematic, as
-    # it makes updating U-Boot cumbersome, since it will go above the current
-    # threshold of rebuilds
-    #
-    # To prevent these needless rounds of staging for U-Boot builds, we can
-    # limit the inclusion of ubootTools to target platforms where uImage *may*
-    # be produced.
-    #
-    # This command lists those (kernel-named) platforms:
-    #     .../linux $ grep -l uImage ./arch/*/Makefile | cut -d'/' -f3 | sort
-    #
-    # This is still a guesstimation, but since none of our cached platforms
-    # coincide in that list, this gives us "perfect" decoupling here.
-    linuxPlatformsUsingUImage = [
-      "arc"
-      "arm"
-      "csky"
-      "mips"
-      "powerpc"
-      "sh"
-      "sparc"
-      "xtensa"
-    ];
-    needsUbootTools = lib.elem stdenv.hostPlatform.linuxArch linuxPlatformsUsingUImage;
-
     config =
       let
         attrName = attr: "CONFIG_" + attr;
@@ -267,7 +241,6 @@ lib.makeOverridable (
       kmod
       hexdump
     ]
-    ++ optional needsUbootTools ubootTools
     ++ optionals (lib.versionAtLeast version "5.2") [
       cpio
       pahole
@@ -536,12 +509,10 @@ lib.makeOverridable (
       kernelAtLeast = lib.versionAtLeast baseVersion;
     };
 
-    # Some image types need special install targets (e.g. uImage is installed with make uinstall on arm)
+    # Some image types need special install targets
     installTargets = [
       (stdenv.hostPlatform.linux-kernel.installTarget or (
-        if target == "uImage" && stdenv.hostPlatform.linuxArch == "arm" then
-          "uinstall"
-        else if
+        if
           (target == "zImage" || target == "Image.gz" || target == "vmlinuz.efi")
           && builtins.elem stdenv.hostPlatform.linuxArch [
             "arm"