[Buildroot] [PATCH v2 20/23] linux: support custom logo and devicetree files in out-of-tree builds

[Florian Fainelli via buildroot <buildroot@buildroot.org>]

A custom logo and custom devicetree files are added to the kernel
sources, which must not be done in a source directory we do not own.

When either is configured for an out-of-tree build, build from a shadow
of the source directory instead: a tree of real directories containing
symlinks to the files (support/scripts/symlink-tree), where files can
be replaced or added without touching the original. Packages opt in by
setting <pkg>_OUT_OF_TREE_SRCDIR.

Custom files are copied with --remove-destination so that a symlink is
replaced rather than written through.

Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
---
 linux/linux.mk               | 34 ++++++++++++++++-----
 package/pkg-generic.mk       |  5 +++-
 support/scripts/symlink-tree | 58 ++++++++++++++++++++++++++++++++++++
 3 files changed, 89 insertions(+), 8 deletions(-)
 create mode 100755 support/scripts/symlink-tree

diff --git a/linux/linux.mk b/linux/linux.mk
index 5734d78aa9a2..37d143742435 100644
--- a/linux/linux.mk
+++ b/linux/linux.mk
@@ -227,7 +227,7 @@ LINUX_DTSO_NAMES += $(basename $(LINUX_DTSO_LIST))
 define LINUX_COPY_CUSTOM_DTS_FILES
 	$(foreach d, $(LINUX_KERNEL_CUSTOM_DTS_DIR), \
 		@$(call MESSAGE,"Copying devicetree overlay $(d)")$(sep) \
-		$(Q)$(call SYSTEM_RSYNC,$(d),$(LINUX_ARCH_PATH)/boot/dts/)$(sep))
+		$(Q)$(call SYSTEM_RSYNC,$(d),$(LINUX_SRC_ARCH_PATH)/boot/dts/)$(sep))
 endef
 endif
 
@@ -291,14 +291,18 @@ endif
 # for bzImage, arch/i386 and arch/x86_64 do not exist when copying the
 # defconfig file.
 ifeq ($(KERNEL_ARCH),i386)
-LINUX_ARCH_PATH = $(LINUX_DIR)/arch/x86
+LINUX_ARCH_SUBDIR = arch/x86
 else ifeq ($(KERNEL_ARCH),x86_64)
-LINUX_ARCH_PATH = $(LINUX_DIR)/arch/x86
+LINUX_ARCH_SUBDIR = arch/x86
 else ifeq ($(KERNEL_ARCH),sparc64)
-LINUX_ARCH_PATH = $(LINUX_DIR)/arch/sparc
+LINUX_ARCH_SUBDIR = arch/sparc
 else
-LINUX_ARCH_PATH = $(LINUX_DIR)/arch/$(KERNEL_ARCH)
+LINUX_ARCH_SUBDIR = arch/$(KERNEL_ARCH)
 endif
+# Build products (images, dtbs) are in the build directory, but the sources
+# of the kernel, to which custom files are added, may be elsewhere.
+LINUX_ARCH_PATH = $(LINUX_DIR)/$(LINUX_ARCH_SUBDIR)
+LINUX_SRC_ARCH_PATH = $(LINUX_SRCDIR)/$(LINUX_ARCH_SUBDIR)
 
 ifeq ($(BR2_LINUX_KERNEL_VMLINUX),y)
 LINUX_IMAGE_PATH = $(LINUX_DIR)/$(LINUX_IMAGE_NAME)
@@ -356,13 +360,29 @@ LINUX_KERNEL_CUSTOM_LOGO_PATH = $(call qstrip,$(BR2_LINUX_KERNEL_CUSTOM_LOGO_PAT
 ifneq ($(LINUX_KERNEL_CUSTOM_LOGO_PATH),)
 LINUX_DEPENDENCIES += host-imagemagick
 define LINUX_KERNEL_CUSTOM_LOGO_CONVERT
+	rm -f $(LINUX_SRCDIR)/drivers/video/logo/logo_linux_clut224.ppm
 	$(HOST_DIR)/bin/convert $(LINUX_KERNEL_CUSTOM_LOGO_PATH) \
 		-dither None -colors 224 -compress none \
-		$(LINUX_DIR)/drivers/video/logo/logo_linux_clut224.ppm
+		$(LINUX_SRCDIR)/drivers/video/logo/logo_linux_clut224.ppm
 endef
 LINUX_PRE_BUILD_HOOKS += LINUX_KERNEL_CUSTOM_LOGO_CONVERT
 endif
 
+# A custom logo or custom devicetree files are added to the kernel sources,
+# which we must not do in a source directory we do not own. In an out-of-tree
+# build, use a shadow of that directory instead: a tree of real directories
+# containing symlinks to the files, so that those can be replaced or added.
+ifneq ($(LINUX_OVERRIDE_SRCDIR),)
+ifneq ($(LINUX_KERNEL_CUSTOM_LOGO_PATH)$(LINUX_KERNEL_CUSTOM_DTS_DIR)$(LINUX_CUSTOM_DTS_PATH),)
+LINUX_OUT_OF_TREE_SRCDIR = $(BUILD_DIR)/linux-custom-src
+define LINUX_SHADOW_SRCDIR
+	@$(call MESSAGE,"Shadowing $(LINUX_OVERRIDE_SRCDIR) for custom files")
+	support/scripts/symlink-tree -F -l .git $(call qstrip,$(LINUX_OVERRIDE_SRCDIR)) $(LINUX_OUT_OF_TREE_SRCDIR)
+endef
+LINUX_PRE_RSYNC_HOOKS += LINUX_SHADOW_SRCDIR
+endif
+endif
+
 ifeq ($(BR2_LINUX_KERNEL_USE_DEFCONFIG),y)
 LINUX_KCONFIG_DEFCONFIG = $(call qstrip,$(BR2_LINUX_KERNEL_DEFCONFIG))_defconfig
 else ifeq ($(BR2_LINUX_KERNEL_USE_ARCH_DEFAULT_CONFIG),y)
@@ -561,7 +581,7 @@ endif
 define LINUX_BUILD_CMDS
 	$(call KCONFIG_DISABLE_OPT,CONFIG_GCC_PLUGINS)
 	$(foreach dts,$(call qstrip,$(BR2_LINUX_KERNEL_CUSTOM_DTS_PATH)), \
-		cp -f $(dts) $(LINUX_ARCH_PATH)/boot/dts/
+		cp -f --remove-destination $(dts) $(LINUX_SRC_ARCH_PATH)/boot/dts/
 	)
 	$(LINUX_COPY_CUSTOM_DTS_FILES)
 	$(LINUX_MAKE_ENV) $(BR2_MAKE) $(LINUX_MAKE_FLAGS) -C $(@D) all
diff --git a/package/pkg-generic.mk b/package/pkg-generic.mk
index b9808bb624f7..14378deacd35 100644
--- a/package/pkg-generic.mk
+++ b/package/pkg-generic.mk
@@ -581,7 +581,10 @@ ifeq ($$($(3)_SUPPORTS_OUT_OF_TREE),YES)
 $(2)_OUT_OF_TREE = YES
 $(2)_SRCDIR = $$(SRC_DIR)/$$($(2)_BASENAME)
 ifneq ($$($(2)_OVERRIDE_SRCDIR),)
-$(2)_SRCDIR = $$(abspath $$(call qstrip,$$($(2)_OVERRIDE_SRCDIR)))
+# A package may need to add files to its sources, which must not be done in
+# the overridden directory: it can then set <pkg>_OUT_OF_TREE_SRCDIR to
+# a shadow of the sources (see support/scripts/symlink-tree).
+$(2)_SRCDIR = $$(or $$($(3)_OUT_OF_TREE_SRCDIR),$$(abspath $$(call qstrip,$$($(2)_OVERRIDE_SRCDIR))))
 $(2)_STAMP_SRCDIR = $$($(2)_BUILDDIR)
 endif
 endif
diff --git a/support/scripts/symlink-tree b/support/scripts/symlink-tree
new file mode 100755
index 000000000000..6c51022dddad
--- /dev/null
+++ b/support/scripts/symlink-tree
@@ -0,0 +1,58 @@
+#!/usr/bin/env bash
+
+# Create a "shadow" of a source tree: a tree of real directories whose
+# files are symlinks to the files of the original tree. Files can then be
+# added to, or replaced in, the shadow, and objects can be built inside it,
+# without ever modifying the original tree.
+#
+# Usage: symlink-tree [-F] [-f NAME]... [-l NAME]... SRC DST
+#
+#   -F       shadow every top-level entry of SRC (default: a single symlink
+#            for each top-level entry)
+#   -f NAME  shadow the top-level directory NAME
+#   -l NAME  only symlink the top-level entry NAME, even with -F
+#
+# DST is wiped and re-created.
+
+set -e
+
+all=false
+farm=" "
+link=" "
+while getopts "Ff:l:" opt; do
+    case "${opt}" in
+    F) all=true ;;
+    f) farm="${farm}${OPTARG} " ;;
+    l) link="${link}${OPTARG} " ;;
+    *) exit 1 ;;
+    esac
+done
+shift $((OPTIND - 1))
+[ $# -eq 2 ] || { echo "usage: ${0##*/} [-F] [-f NAME]... [-l NAME]... SRC DST" >&2; exit 1; }
+
+src="$(readlink -f "${1}")"
+dst="${2}"
+
+# Refuse to wipe anything that does not look like a previous shadow, or
+# that could be (part of) the source tree.
+dst_abs="$(readlink -m "${dst}")"
+case "${src}/" in
+"${dst_abs}"/*) echo "${0##*/}: ${dst} contains the source tree" >&2; exit 1 ;;
+esac
+case "${dst_abs}/" in
+"${src}"/*) echo "${0##*/}: ${dst} is inside the source tree" >&2; exit 1 ;;
+esac
+
+rm -rf "${dst}"
+mkdir -p "${dst}"
+
+for path in "${src}"/* "${src}"/.[!.]* "${src}"/..?*; do
+    [ -e "${path}" ] || [ -L "${path}" ] || continue
+    name="${path##*/}"
+    if [ -d "${path}" ] && [ ! -L "${path}" ] && [[ "${link}" != *" ${name} "* ]] &&
+       { ${all} || [[ "${farm}" == *" ${name} "* ]]; }; then
+        cp -rs "${path}" "${dst}/"
+    else
+        ln -s "${path}" "${dst}/${name}"
+    fi
+done
-- 
2.34.1

_______________________________________________
buildroot mailing list
buildroot@buildroot.org
https://lists.buildroot.org/mailman/listinfo/buildroot