kbuild: use $(src) instead of $(srctree)/$(src) for source directory

Kbuild conventionally uses $(obj)/ for generated files, and $(src)/ for
checked-in source files. It is merely a convention without any functional
difference. In fact, $(obj) and $(src) are exactly the same, as defined
in scripts/Makefile.build:

    src := $(obj)

When the kernel is built in a separate output directory, $(src) does
not accurately reflect the source directory location. While Kbuild
resolves this discrepancy by specifying VPATH=$(srctree) to search for
source files, it does not cover all cases. For example, when adding a
header search path for local headers, -I$(srctree)/$(src) is typically
passed to the compiler.

This introduces inconsistency between upstream and downstream Makefiles
because $(src) is used instead of $(srctree)/$(src) for the latter.

To address this inconsistency, this commit changes the semantics of
$(src) so that it always points to the directory in the source tree.

Going forward, the variables used in Makefiles will have the following
meanings:

  $(obj)     - directory in the object tree
  $(src)     - directory in the source tree  (changed by this commit)
  $(objtree) - the top of the kernel object tree
  $(srctree) - the top of the kernel source tree

Consequently, $(srctree)/$(src) in upstream Makefiles need to be replaced
with $(src).

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>

1 files changed, 2 insertions, 2 deletions

diff --git a/certs/Makefile b/certs/Makefile
index 799ad7b9e68a..1094e3860c2a 100644
--- a/certs/Makefile
+++ b/certs/Makefile
@@ -13,7 +13,7 @@ CFLAGS_blacklist_hashes.o := -I $(obj)
 quiet_cmd_check_and_copy_blacklist_hash_list = GEN     $@
       cmd_check_and_copy_blacklist_hash_list = \
 	$(if $(CONFIG_SYSTEM_BLACKLIST_HASH_LIST), \
-	$(AWK) -f $(srctree)/$(src)/check-blacklist-hashes.awk $(CONFIG_SYSTEM_BLACKLIST_HASH_LIST) >&2; \
+	$(AWK) -f $(src)/check-blacklist-hashes.awk $(CONFIG_SYSTEM_BLACKLIST_HASH_LIST) >&2; \
 	{ cat $(CONFIG_SYSTEM_BLACKLIST_HASH_LIST); echo $(comma) NULL; } > $@, \
 	echo NULL > $@)
 
@@ -55,7 +55,7 @@ $(obj)/signing_key.pem: $(obj)/x509.genkey FORCE
 targets += signing_key.pem
 
 quiet_cmd_copy_x509_config = COPY    $@
-      cmd_copy_x509_config = cat $(srctree)/$(src)/default_x509.genkey > $@
+      cmd_copy_x509_config = cat $(src)/default_x509.genkey > $@
 
 # You can provide your own config file. If not present, copy the default one.
 $(obj)/x509.genkey: