Kbuild fixes for v6.2 (3rd)

- Hide LDFLAGS_vmlinux from decompressor Makefiles to fix error messages
    when GNU Make 4.4 is used.
 
  - Fix 'make modules' build error when CONFIG_DEBUG_INFO_BTF_MODULES=y.
 
  - Fix warnings emitted by GNU Make 4.4 in scripts/kconfig/Makefile.
 
  - Support GNU Make 4.4 for scripts/jobserver-exec.
 
  - Show clearer error message when kernel/gen_kheaders.sh fails due to
    missing cpio.
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Merge tag 'kbuild-fixes-v6.2-3' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild fixes from Masahiro Yamada:

 - Hide LDFLAGS_vmlinux from decompressor Makefiles to fix error
   messages when GNU Make 4.4 is used.

 - Fix 'make modules' build error when CONFIG_DEBUG_INFO_BTF_MODULES=y.

 - Fix warnings emitted by GNU Make 4.4 in scripts/kconfig/Makefile.

 - Support GNU Make 4.4 for scripts/jobserver-exec.

 - Show clearer error message when kernel/gen_kheaders.sh fails due to
   missing cpio.

* tag 'kbuild-fixes-v6.2-3' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  kheaders: explicitly validate existence of cpio command
  scripts: support GNU make 4.4 in jobserver-exec
  kconfig: Update all declared targets
  scripts: rpm: make clear that mkspec script contains 4.13 feature
  init/Kconfig: fix LOCALVERSION_AUTO help text
  kbuild: fix 'make modules' error when CONFIG_DEBUG_INFO_BTF_MODULES=y
  kbuild: export top-level LDFLAGS_vmlinux only to scripts/Makefile.vmlinux
  init/version-timestamp.c: remove unneeded #include <linux/version.h>
  docs: kbuild: remove mention to dropped $(objtree) feature

Documentation/kbuild/makefiles.rst

@@ -1042,7 +1042,7 @@ $(clean-files).
 
 When executing "make clean", the file "crc32table.h" will be deleted.
 Kbuild will assume files to be in the same relative directory as the
-Makefile, except if prefixed with $(objtree).
+Makefile.
 
 To exclude certain files or directories from make clean, use the
 $(no-clean-files) variable.

Makefile

@@ -549,7 +549,7 @@ LDFLAGS_MODULE  =
 CFLAGS_KERNEL	=
 RUSTFLAGS_KERNEL =
 AFLAGS_KERNEL	=
-export LDFLAGS_vmlinux =
+LDFLAGS_vmlinux =
 
 # Use USERINCLUDE when you must reference the UAPI directories only.
 USERINCLUDE    := \
@@ -1248,6 +1248,18 @@ vmlinux.o modules.builtin.modinfo modules.builtin: vmlinux_o
 	@:
 
 PHONY += vmlinux
+# LDFLAGS_vmlinux in the top Makefile defines linker flags for the top vmlinux,
+# not for decompressors. LDFLAGS_vmlinux in arch/*/boot/compressed/Makefile is
+# unrelated; the decompressors just happen to have the same base name,
+# arch/*/boot/compressed/vmlinux.
+# Export LDFLAGS_vmlinux only to scripts/Makefile.vmlinux.
+#
+# _LDFLAGS_vmlinux is a workaround for the 'private export' bug:
+#   https://savannah.gnu.org/bugs/?61463
+# For Make > 4.4, the following simple code will work:
+#  vmlinux: private export LDFLAGS_vmlinux := $(LDFLAGS_vmlinux)
+vmlinux: private _LDFLAGS_vmlinux := $(LDFLAGS_vmlinux)
+vmlinux: export LDFLAGS_vmlinux = $(_LDFLAGS_vmlinux)
 vmlinux: vmlinux.o $(KBUILD_LDS) modpost
 	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.vmlinux
 
@@ -1533,6 +1545,7 @@ endif
 # *.ko are usually independent of vmlinux, but CONFIG_DEBUG_INFOBTF_MODULES
 # is an exception.
 ifdef CONFIG_DEBUG_INFO_BTF_MODULES
+KBUILD_BUILTIN := 1
 modules: vmlinux
 endif
 

init/Kconfig

@@ -204,7 +204,7 @@ config LOCALVERSION_AUTO
 	  appended after any matching localversion* files, and after the value
 	  set in CONFIG_LOCALVERSION.
 
-	  (The actual string used here is the first eight characters produced
+	  (The actual string used here is the first 12 characters produced
 	  by running the command:
 
 	    $ git rev-parse --verify HEAD

init/version-timestamp.c

@@ -2,7 +2,6 @@
 
 #include <generated/compile.h>
 #include <generated/utsrelease.h>
-#include <linux/version.h>
 #include <linux/proc_ns.h>
 #include <linux/refcount.h>
 #include <linux/uts.h>

kernel/gen_kheaders.sh

@@ -14,6 +14,8 @@ include/
 arch/$SRCARCH/include/
 "
 
+type cpio > /dev/null
+
 # Support incremental builds by skipping archive generation
 # if timestamps of files being archived are not changed.
 

scripts/jobserver-exec

@@ -26,11 +26,20 @@ try:
 	# If the MAKEFLAGS variable contains multiple instances of the
 	# --jobserver-auth= option, the last one is relevant.
 	fds = opts[-1].split("=", 1)[1]
-	reader, writer = [int(x) for x in fds.split(",", 1)]
-	# Open a private copy of reader to avoid setting nonblocking
-	# on an unexpecting process with the same reader fd.
-	reader = os.open("/proc/self/fd/%d" % (reader),
-			 os.O_RDONLY | os.O_NONBLOCK)
+
+	# Starting with GNU Make 4.4, named pipes are used for reader and writer.
+	# Example argument: --jobserver-auth=fifo:/tmp/GMfifo8134
+	_, _, path = fds.partition('fifo:')
+
+	if path:
+		reader = os.open(path, os.O_RDONLY | os.O_NONBLOCK)
+		writer = os.open(path, os.O_WRONLY)
+	else:
+		reader, writer = [int(x) for x in fds.split(",", 1)]
+		# Open a private copy of reader to avoid setting nonblocking
+		# on an unexpecting process with the same reader fd.
+		reader = os.open("/proc/self/fd/%d" % (reader),
+				 os.O_RDONLY | os.O_NONBLOCK)
 
 	# Read out as many jobserver slots as possible.
 	while True:

scripts/kconfig/.gitignore

@@ -1,7 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0-only
 /conf
 /[gmnq]conf
+/[gmnq]conf-bin
 /[gmnq]conf-cflags
 /[gmnq]conf-libs
-/qconf-bin
 /qconf-moc.cc

scripts/kconfig/Makefile

@@ -209,7 +209,7 @@ $(obj)/gconf: | $(obj)/gconf-libs
 $(obj)/gconf.o: | $(obj)/gconf-cflags
 
 # check if necessary packages are available, and configure build flags
-cmd_conf_cfg = $< $(addprefix $(obj)/$*conf-, cflags libs bin)
+cmd_conf_cfg = $< $(addprefix $(obj)/$*conf-, cflags libs bin); touch $(obj)/$*conf-bin
 
 $(obj)/%conf-cflags $(obj)/%conf-libs $(obj)/%conf-bin: $(src)/%conf-cfg.sh
 	$(call cmd,conf_cfg)

scripts/package/mkspec

@@ -1,7 +1,7 @@
 #!/bin/sh
 #
 #	Output a simple RPM spec file.
-#	This version assumes a minimum of RPM 4.0.3.
+#	This version assumes a minimum of RPM 4.13
 #
 #	The only gothic bit here is redefining install_post to avoid
 #	stripping the symbols from files in the kernel which we want