Re: [RFC PATCH v2 6/7] livepatch/klp-build: add pre-built object support for advanced OOT workflows

[Josh Poimboeuf <jpoimboe@kernel.org>]

On Wed, Aug 26, 2026 at 03:49:59PM -0400, Joe Lawrence wrote:
> +setup_oot() {
> +	local files=()
> +	local rel
> +
> +	mkdir -p "$ORIG_DIR" "$PATCHED_DIR"
> +
> +	find "$USER_ORIG_DIR" -type f -name "*.o" -printf '%P\n' | mapfile -t files
> +	[[ ${#files[@]} -gt 0 ]] || die "no .o files found in $USER_ORIG_DIR"
> +	for rel in "${files[@]}"; do
> +		[[ -f "$USER_PATCHED_DIR/$rel" ]] ||
> +			die "$rel found in orig dir but missing from patched dir"
> +		mkdir -p "$ORIG_DIR/$(dirname "$rel")"
> +		mkdir -p "$PATCHED_DIR/$(dirname "$rel")"
> +		cp -f "$USER_ORIG_DIR/$rel" "$ORIG_DIR/$rel"
> +		cp -f "$USER_PATCHED_DIR/$rel" "$PATCHED_DIR/$rel"
> +	done
> +
> +	touch "$ORIG_DIR/.complete"
> +	touch "$PATCHED_DIR/.complete"
> +}

This is basically reimplementing copy_orig_objects() and copy_patched_objects().

>  ################################################################################
>  
>  process_args "$@"
>  do_init
>  
> +# User provided OOT original and patched object files can jump straight
> +# to checksum + diff + build steps
> +if [[ -n "$USER_ORIG_DIR" ]]; then
> +	status "Setting up OOT objects"
> +	setup_oot
> +
> +	status "Generating original checksums"
> +	generate_checksums "$ORIG_DIR" "$ORIG_CSUM_DIR" "$PATCHED_DIR"
> +	status "Generating patched checksums"
> +	generate_checksums "$PATCHED_DIR" "$PATCHED_CSUM_DIR"
> +
> +	status "Diffing objects"
> +	diff_objects
> +
> +	status "Building patch module: $OUTFILE"
> +	build_patch_module
> +
> +	status "SUCCESS"
> +	exit 0
> +fi

This is basically reimplementing --short-circuit=3.

Instead of --orig-dir and --patched-dir, I wonder if we could just have
--oot-build-cmd (combined with --oot-dir), so the user can specify
whatever make command is needed?

Then do_init() could have something like SRC_DIR="${OOT_DIR:-$PWD}" so
almost all the code for all the steps gets shared, except for the build
command.

The klp-specific build-isms like KCFLAGS could be exported instead of
added to the cmdline.

And then that would be easier for the user too, they wouldn't have to do
the building/copying of objects, filtering the patch, etc.

-- 
Josh