linux: add setup hook for kernel compression

This setup hook ensures that kernel modules are compressed with
parameters the kernel is capable of decompressing. This is currently
only effective when xz is used as the kernel module compression
algorithm.

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

@@ -23,6 +23,8 @@
   rustc-unwrapped,
   rust-bindgen-unwrapped,
   rustPlatform,
+  makeSetupHook,
+  xz,
 }:
 
 let
@@ -158,6 +160,11 @@ lib.makeOverridable (
       elfutils
       # module makefiles often run uname commands to find out the kernel version
       (buildPackages.deterministic-uname.override { inherit modDirVersion; })
+      (makeSetupHook {
+        name = "setup-module-compression";
+        substitutions = { inherit configfile modDirVersion; };
+        propagatedNativeBuildInputs = [ xz ];
+      } ./setup-module-compression.sh)
     ]
     ++ optional (lib.versionAtLeast version "5.13") zstd
     ++ optionals withRust [

pkgs/os-specific/linux/kernel/setup-module-compression.sh

@@ -0,0 +1,11 @@
+# shellcheck shell=bash
+
+setupModuleCompressionHook() {
+  # Ensure CRC32 is used, which the kernel is capable of decompressing natively (enabled by CONFIG_MODULE_DECOMPRESS=y).
+  export XZ_OPT="--check=crc32"
+}
+
+if [[ -z "${dontSetupModuleCompression-}" ]]; then
+  nixInfoLog "Using setupModuleCompressionHook"
+  postConfigureHooks+=(setupModuleCompressionHook)
+fi