kernel: introduce hook kernel_extra_create_patches

- immediately after `kernel_drivers_create_patches`
- immediately before actually applying kernel sources
- this helps boards/families/extensions that need to stage out-of-tree
  patches into eg userpatches, without impacting the patches hash
- the hook itself is hashed, so changes to it do impact the hooks hash

Author: rpardini

lib/functions/artifacts/artifact-kernel.sh

@@ -151,7 +151,10 @@ function artifact_kernel_prepare_version() {
 	declare var_config_hash_short="${vars_config_hash:0:${short_hash_size}}"
 
 	# Hash the extension hooks
-	declare -a extension_hooks_to_hash=("pre_package_kernel_image" "kernel_copy_extra_sources" "pre_package_kernel_headers")
+	declare -a extension_hooks_to_hash=(
+		"pre_package_kernel_image" "kernel_copy_extra_sources" "pre_package_kernel_headers"
+		"kernel_extra_create_patches"
+	)
 	declare -a extension_hooks_hashed=("$(dump_extension_method_sources_functions "${extension_hooks_to_hash[@]}")")
 	declare hash_hooks="undetermined"
 	hash_hooks="$(echo "${extension_hooks_hashed[@]}" | sha256sum | cut -d' ' -f1)"

lib/functions/compilation/kernel-patching.sh

@@ -75,6 +75,14 @@ function kernel_main_patching() {
 	declare kernel_drivers_patch_file kernel_drivers_patch_hash
 	LOG_SECTION="kernel_drivers_create_patches" do_with_logging do_with_hooks kernel_drivers_create_patches "${kernel_work_dir}" "${kernel_git_revision}"
 
+	call_extension_method "kernel_extra_create_patches" <<- 'KERNEL_EXTRA_CREATE_PATCHES'
+		*stage more patches for kernel, after kernel_drivers*
+		This is called after kernel_drivers_create_patches (wifi-drivers) and can be used to stage more patches
+		to be applied. This is done immediately before actually patching, and thus, after any hashing is done.
+		This allows implementors to stage custom patches (eg, from an out-of-tree driver into userpatches) without
+		impacting the kernel version/hash.
+	KERNEL_EXTRA_CREATE_PATCHES
+
 	# Python patching will git reset to the kernel SHA1 git revision, and remove all untracked files.
 	LOG_SECTION="kernel_main_patching_python" do_with_logging do_with_hooks kernel_main_patching_python