build: Add prune targets

These reduce the size of the kernel/selftest build directory, but leave
artifacts like the vmlinux around.

Author: mpe

build/Makefile

@@ -53,6 +53,9 @@ kernel@${1}@${2}: image@${1}@${2}
 clean-kernel@${1}@${2}:
 	@./scripts/clean.sh $$@
 
+prune-kernel@${1}@${2}:
+	@./scripts/prune.sh $$@
+
 KERNEL += $(if $(filter-out ${ALIAS_DISTROS},${2}), kernel@${1}@${2})
 endef
 
@@ -63,6 +66,9 @@ ppctests@${1}@${2} selftests@${1}@${2}: image@${1}@${2}
 clean-selftests@${1}@${2}:
 	@./scripts/clean.sh $$@
 
+prune-selftests@${1}@${2}:
+	@./scripts/prune.sh $$@
+
 PPCTESTS += $(if $(filter-out ${ALIAS_DISTROS},${2}), ppctests@${1}@${2})
 SELFTESTS += $(if $(filter-out ${ALIAS_DISTROS},${2}), selftests@${1}@${2})
 endef

build/scripts/lib.sh

@@ -41,6 +41,7 @@ function get_output_dir()
 
     case "$task" in
         kernel) ;&
+        prune-kernel) ;&
         clean-kernel)
 	    if [[ -n "$symlink" ]]; then
 		echo "$d/latest-kernel"
@@ -53,6 +54,7 @@ function get_output_dir()
             ;;
         ppctests) ;&
         selftests) ;&
+        prune-selftests) ;&
         clean-selftests)
 	    if [[ -n "$symlink" ]]; then
 		echo "$d/latest-selftests"

build/scripts/prune.sh

@@ -0,0 +1,60 @@
+#!/bin/bash
+
+if [[ -z "$1" ]]; then
+    echo "Usage: $0 <target>" >&2
+    exit 1
+fi
+
+dir="$(dirname "$0")"
+script_base="$(realpath "$dir")"
+. "$script_base/lib.sh"
+
+IFS=@ read -r task subarch distro version <<< "$1"
+
+output_dir=$(get_output_dir "$script_base" "$subarch" "$distro" "$version" "$task" "$DEFCONFIG" "$TARGETS" "$CLANG")
+
+case "$task" in
+    prune-kernel)
+        if [[ ! -e "$output_dir/Makefile" ]]; then
+            # Assume it's already been pruned
+            exit 0
+        fi
+
+        echo "Pruning non-outputs in $output_dir"
+
+        set -euo pipefail
+        cd "$output_dir"
+        mkdir -p "artifacts"
+        for path in .config vmlinux System.map arch/powerpc/boot/zImage include/config/kernel.release \
+                    arch/powerpc/kernel/asm-offsets.s arch/powerpc/boot/uImage modules.tar.bz2 \
+                    sparse.log log.txt
+        do
+            if [[ -e "$path" ]]; then
+                mv "$path" artifacts/
+            fi
+        done
+        find . -not -path "./artifacts*" -delete
+        mv artifacts/.config config
+        mv artifacts/* .
+        rmdir artifacts
+        ;;
+    prune-selftests)
+        if [[ ! -e "$output_dir/kselftest" ]]; then
+            # Assume it's already been pruned
+            exit 0
+        fi
+
+        echo "Pruning non-outputs in $output_dir"
+
+        set -euo pipefail
+        cd "$output_dir"
+        if [[ -d install ]]; then
+            mv install selftests
+            tar -cJf selftests.tar.xz selftests
+        fi
+        find . -not -path "./selftests.tar.xz" -delete
+        ;;
+    *)
+        (set -x ; rm -rf "$output_dir")
+        ;;
+esac