From cdd750bfb1f76fe9be8cfb53cbe77b2e811081ab Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Mon, 13 May 2019 15:22:17 +0900 Subject: kbuild: remove 'addtree' and 'flags' magic for header search paths The 'addtree' and 'flags' in scripts/Kbuild.include are so compilecated and ugly. As I mentioned in [1], Kbuild should stop automatic prefixing of header search path options. I fixed up (almost) all Makefiles in the kernel. Now 'addtree' and 'flags' have been removed. Kbuild still caters to add $(srctree)/$(src) and $(objtree)/$(obj) to the header search path for O= building, but never touches extra compiler options from ccflags-y etc. [1]: https://patchwork.kernel.org/patch/9632347/ Signed-off-by: Masahiro Yamada --- scripts/Kbuild.include | 8 -------- 1 file changed, 8 deletions(-) (limited to 'scripts/Kbuild.include') diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include index 7484b9d8272f..a675ce11a573 100644 --- a/scripts/Kbuild.include +++ b/scripts/Kbuild.include @@ -192,14 +192,6 @@ clean := -f $(srctree)/scripts/Makefile.clean obj # $(Q)$(MAKE) $(hdr-inst)=dir hdr-inst := -f $(srctree)/scripts/Makefile.headersinst obj -# Prefix -I with $(srctree) if it is not an absolute path. -# skip if -I has no parameter -addtree = $(if $(patsubst -I%,%,$(1)), \ -$(if $(filter-out -I/% -I./% -I../%,$(1)),$(patsubst -I%,-I$(srctree)/%,$(1)),$(1)),$(1)) - -# Find all -I options and call addtree -flags = $(foreach o,$($(1)),$(if $(filter -I%,$(o)),$(call addtree,$(o)),$(o))) - # echo command. # Short version is used, if $(quiet) equals `quiet_', otherwise full one. echo-cmd = $(if $($(quiet)cmd_$(1)),\ -- cgit v1.2.3 From 055efab3120bae7ab1ed841317774f3c953f6e1b Mon Sep 17 00:00:00 2001 From: Nick Desaulniers Date: Tue, 23 Apr 2019 14:27:41 -0700 Subject: kbuild: drop support for cc-ldoption If you want to see if your linker supports a certain flag, then ask the linker directly with ld-option (not the compiler with cc-ldoption). Checking for linker flag support is an antipattern that complicates the usage of various linkers other than bfd via -fuse-ld={bfd|gold|lld}. Cc: clang-built-linux@googlegroups.com Suggested-by: Masahiro Yamada Signed-off-by: Nick Desaulniers Signed-off-by: Masahiro Yamada --- scripts/Kbuild.include | 5 ----- 1 file changed, 5 deletions(-) (limited to 'scripts/Kbuild.include') diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include index a675ce11a573..e2de6c4dce90 100644 --- a/scripts/Kbuild.include +++ b/scripts/Kbuild.include @@ -138,11 +138,6 @@ cc-disable-warning = $(call try-run,\ # Usage: EXTRA_CFLAGS += $(call cc-ifversion, -lt, 0402, -O1) cc-ifversion = $(shell [ $(CONFIG_GCC_VERSION)0 $(1) $(2)000 ] && echo $(3) || echo $(4)) -# cc-ldoption -# Usage: ldflags += $(call cc-ldoption, -Wl$(comma)--hash-style=both) -cc-ldoption = $(call try-run,\ - $(CC) $(1) $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) -nostdlib -x c /dev/null -o "$$TMP",$(1),$(2)) - # ld-option # Usage: KBUILD_LDFLAGS += $(call ld-option, -X, -Y) ld-option = $(call try-run, $(LD) $(KBUILD_LDFLAGS) $(1) -v,$(1),$(2),$(3)) -- cgit v1.2.3 From 96ac6d435100450f0565708d9b885ea2a7400e0a Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Thu, 30 May 2019 05:03:44 -0700 Subject: treewide: Add SPDX license identifier - Kbuild Add SPDX license identifiers to all Make/Kconfig files which: - Have no license information of any form These files fall under the project license, GPL v2 only. The resulting SPDX license identifier is: GPL-2.0 Reported-by: Masahiro Yamada Signed-off-by: Greg Kroah-Hartman Reviewed-by: Kate Stewart Signed-off-by: Greg Kroah-Hartman --- scripts/Kbuild.include | 1 + 1 file changed, 1 insertion(+) (limited to 'scripts/Kbuild.include') diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include index e2de6c4dce90..85d758233483 100644 --- a/scripts/Kbuild.include +++ b/scripts/Kbuild.include @@ -1,3 +1,4 @@ +# SPDX-License-Identifier: GPL-2.0 #### # kbuild: Generic definitions -- cgit v1.2.3 From 913ab9780fc021298949cc5514d6255a008e69f9 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Thu, 6 Jun 2019 13:13:58 +0900 Subject: kbuild: use more portable 'command -v' for cc-cross-prefix To print the pathname that will be used by shell in the current environment, 'command -v' is a standardized way. [1] 'which' is also often used in scripts, but it is less portable. When I worked on commit bd55f96fa9fc ("kbuild: refactor cc-cross-prefix implementation"), I was eager to use 'command -v' but it did not work. (The reason is explained below.) I kept 'which' as before but got rid of '> /dev/null 2>&1' as I thought it was no longer needed. Sorry, I was wrong. It works well on my Ubuntu machine, but Alexey Brodkin reports noisy warnings on CentOS7 when 'which' fails to find the given command in the PATH environment. $ which foo which: no foo in (/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin) Given that behavior of 'which' depends on system (and it may not be installed by default), I want to try 'command -v' once again. The specification [1] clearly describes the behavior of 'command -v' when the given command is not found: Otherwise, no output shall be written and the exit status shall reflect that the name was not found. However, we need a little magic to use 'command -v' from Make. $(shell ...) passes the argument to a subshell for execution, and returns the standard output of the command. Here is a trick. GNU Make may optimize this by executing the command directly instead of forking a subshell, if no shell special characters are found in the command and omitting the subshell will not change the behavior. In this case, no shell special character is used. So, Make will try to run it directly. However, 'command' is a shell-builtin command, then Make would fail to find it in the PATH environment: $ make ARCH=m68k defconfig make: command: Command not found make: command: Command not found make: command: Command not found In fact, Make has a table of shell-builtin commands because it must ask the shell to execute them. Until recently, 'command' was missing in the table. This issue was fixed by the following commit: | commit 1af314465e5dfe3e8baa839a32a72e83c04f26ef | Author: Paul Smith | Date: Sun Nov 12 18:10:28 2017 -0500 | | * job.c: Add "command" as a known shell built-in. | | This is not a POSIX shell built-in but it's common in UNIX shells. | Reported by Nick Bowler . Because the latest release is GNU Make 4.2.1 in 2016, this commit is not included in any released versions. (But some distributions may have back-ported it.) We need to trick Make to spawn a subshell. There are various ways to do so: 1) Use a shell special character '~' as dummy $(shell : ~; command -v $(c)gcc) 2) Use a variable reference that always expands to the empty string (suggested by David Laight) $(shell command$${x:+} -v $(c)gcc) 3) Use redirect $(shell command -v $(c)gcc 2>/dev/null) I chose 3) to not confuse people. The stderr would not be polluted anyway, but it will provide extra safety, and is easy to understand. Tested on Make 3.81, 3.82, 4.0, 4.1, 4.2, 4.2.1 [1] http://pubs.opengroup.org/onlinepubs/9699919799/utilities/command.html Fixes: bd55f96fa9fc ("kbuild: refactor cc-cross-prefix implementation") Cc: linux-stable # 5.1 Reported-by: Alexey Brodkin Signed-off-by: Masahiro Yamada Tested-by: Alexey Brodkin --- scripts/Kbuild.include | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'scripts/Kbuild.include') diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include index 85d758233483..f641bb0aa63f 100644 --- a/scripts/Kbuild.include +++ b/scripts/Kbuild.include @@ -74,8 +74,13 @@ endef # Usage: CROSS_COMPILE := $(call cc-cross-prefix, m68k-linux-gnu- m68k-linux-) # Return first where a gcc is found in PATH. # If no gcc found in PATH with listed prefixes return nothing +# +# Note: '2>/dev/null' is here to force Make to invoke a shell. Otherwise, it +# would try to directly execute the shell builtin 'command'. This workaround +# should be kept for a long time since this issue was fixed only after the +# GNU Make 4.2.1 release. cc-cross-prefix = $(firstword $(foreach c, $(filter-out -%, $(1)), \ - $(if $(shell which $(c)gcc), $(c)))) + $(if $(shell command -v $(c)gcc 2>/dev/null), $(c)))) # output directory for tests below TMPOUT := $(if $(KBUILD_EXTMOD),$(firstword $(KBUILD_EXTMOD))/) -- cgit v1.2.3