user/sven/linux.git/scripts/Kbuild.include, branch v5.1.19

kbuild: use more portable 'command -v' for cc-cross-prefix

2019-06-11T10:19:16Z

commit 913ab9780fc021298949cc5514d6255a008e69f9 upstream. 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 Signed-off-by: Greg Kroah-Hartman

kbuild: remove cc-version macro

2019-03-04T13:34:59Z

There is no more direct user of this macro; it is only used by cc-ifversion. Calling this macro is not efficient since it invokes the compiler to get the compiler version. CONFIG_GCC_VERSION is already calculated in the Kconfig stage, so Makefile can reuse it. Here is a note about the slight difference between cc-version and CONFIG_GCC_VERSION: When using Clang, cc-version is evaluated to '0402' because Clang defines __GNUC__ and __GNUC__MINOR__, and looks like GCC 4.2 in the version point of view. On the other hand, CONFIG_GCC_VERSION=0 when $(CC) is clang. There are currently two users of cc-ifversion: arch/mips/loongson64/Platform arch/powerpc/Makefile They are not affected by this change. The format of cc-version is , while CONFIG_GCC_VERSION . I adjusted cc-ifversion for the difference of the number of digits. Signed-off-by: Masahiro Yamada

kbuild: refactor cc-cross-prefix implementation

2019-02-27T12:41:27Z

- $(word 1, ) is equivalent to $(firstword ) - hardcode "gcc" instead of $(CC) - minimize the shell script part A little more notes in case $(filter-out -%, ...) is not clear. arch/mips/Makefile passes prefixes depending on the configuration. CROSS_COMPILE := $(call cc-cross-prefix, $(tool-archpref)-linux- \ $(tool-archpref)-linux-gnu- $(tool-archpref)-unknown-linux-gnu-) In the Kconfig stage (e.g. when you run 'make defconfig'), neither CONFIG_32BIT nor CONFIG_64BIT is defined. So, $(tool-archpref) is empty. As a result, "-linux -linux-gnu- -unknown-linux-gnu" is passed into cc-cross-prefix. The command 'which' assumes arguments starting with a hyphen as command options, then emits the following messages: Illegal option -l Illegal option -l Illegal option -u I think it is strange to define CROSS_COMPILE depending on the CONFIG options since you need to feed $(CC) to Kconfig, but it is how MIPS Makefile currently works. Anyway, it would not hurt to filter-out invalid strings beforehand. Signed-off-by: Masahiro Yamada

kbuild: add real-prereqs shorthand for $(filter-out FORCE,$^)

2019-01-28T00:11:17Z

In Kbuild, if_changed and friends must have FORCE as a prerequisite. Hence, $(filter-out FORCE,$^) or $(filter-out $(PHONY),$^) is a common idiom to get the names of all the prerequisites except phony targets. Add real-prereqs as a shorthand. Note: We cannot replace $(filter %.o,$^) in cmd_link_multi-m because $^ may include auto-generated dependencies from the .*.cmd file when a single object module is changed into a multi object module. Refer to commit 69ea912fda74 ("kbuild: remove unneeded link_multi_deps"). I added some comment to avoid accidental breakage. Signed-off-by: Masahiro Yamada Acked-by: Rob Herring

kbuild: remove unused baseprereq

2019-01-14T03:19:40Z

Commit eea199b445f6 ("kbuild: remove unnecessary LEX_PREFIX and YACC_PREFIX") removed the last users of this macro. Signed-off-by: Masahiro Yamada

kbuild: use assignment instead of define ... endef for filechk_* rules

2019-01-06T01:22:35Z

You do not have to use define ... endef for filechk_* rules. For simple cases, the use of assignment looks cleaner, IMHO. I updated the usage for scripts/Kbuild.include in case somebody misunderstands the 'define ... endif' is the requirement. Signed-off-by: Masahiro Yamada Acked-by: Heiko Carstens

kbuild: change filechk to surround the given command with { }

2019-01-06T00:46:51Z

filechk_* rules often consist of multiple 'echo' lines. They must be surrounded with { } or ( ) to work correctly. Otherwise, only the string from the last 'echo' would be written into the target. Let's take care of that in the 'filechk' in scripts/Kbuild.include to clean up filechk_* rules. Signed-off-by: Masahiro Yamada

Merge tag 'kbuild-v4.21' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

2018-12-29T20:03:17Z

Pull Kbuild updates from Masahiro Yamada: "Kbuild core: - remove unneeded $(call cc-option,...) switches - consolidate Clang compiler flags into CLANG_FLAGS - announce the deprecation of SUBDIRS - fix single target build for external module - simplify the dependencies of 'prepare' stage targets - allow fixdep to directly write to .*.cmd files - simplify dependency generation for CONFIG_TRIM_UNUSED_KSYMS - change if_changed_rule to accept multi-line recipe - move .SECONDARY special target to scripts/Kbuild.include - remove redundant 'set -e' - improve parallel execution for CONFIG_HEADERS_CHECK - misc cleanups Treewide fixes and cleanups - set Clang flags correctly for PowerPC boot images - fix UML build error with CONFIG_GCC_PLUGINS - remove unneeded patterns from .gitignore files - refactor firmware/Makefile - remove unneeded rules for *offsets.s - avoid unneeded regeneration of intermediate .s files - clean up ./Kbuild Modpost: - remove unused -M, -K options - fix false positive warnings about section mismatch - use simple devtable lookup instead of linker magic - misc cleanups Coccinelle: - relax boolinit.cocci checks for overall consistency - fix warning messages of boolinit.cocci Other tools: - improve -dirty check of scripts/setlocalversion - add a tool to generate compile_commands.json from .*.cmd files" * tag 'kbuild-v4.21' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (51 commits) kbuild: remove unused cmd_gentimeconst kbuild: remove $(obj)/ prefixes in ./Kbuild treewide: add intermediate .s files to targets treewide: remove explicit rules for *offsets.s firmware: refactor firmware/Makefile firmware: remove unnecessary patterns from .gitignore scripts: remove unnecessary ihex2fw and check-lc_ctypes from .gitignore um: remove unused filechk_gen_header in Makefile scripts: add a tool to produce a compile_commands.json file kbuild: add -Werror=implicit-int flag unconditionally kbuild: add -Werror=strict-prototypes flag unconditionally kbuild: add -fno-PIE flag unconditionally scripts: coccinelle: Correct warning message scripts: coccinelle: only suggest true/false in files that already use them kbuild: handle part-of-module correctly for *.ll and *.symtypes kbuild: refactor part-of-module kbuild: refactor quiet_modtag kbuild: remove redundant quiet_modtag for $(obj-m) kbuild: refactor Makefile.asm-generic user/Makefile: Fix typo and capitalization in comment section ...

Revert "kbuild/Makefile: Prepare for using macros in inline assembly code to work around asm() related GCC inlining bugs"

2018-12-19T11:00:28Z

This reverts commit 77b0bf55bc675233d22cd5df97605d516d64525e. See this commit for details about the revert: e769742d3584 ("Revert "x86/jump-labels: Macrofy inline assembly code to work around GCC inlining bugs"") Conflicts: arch/x86/Makefile Reported-by: Masahiro Yamada Reviewed-by: Borislav Petkov Reviewed-by: Thomas Gleixner Cc: Juergen Gross Cc: Richard Biener Cc: Kees Cook Cc: Segher Boessenkool Cc: Ard Biesheuvel Cc: Peter Zijlstra Cc: Josh Poimboeuf Cc: Nadav Amit Cc: Linus Torvalds Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar

kbuild: move .SECONDARY special target to Kbuild.include

2018-12-02T05:11:49Z

In commit 54a702f70589 ("kbuild: mark $(targets) as .SECONDARY and remove .PRECIOUS markers"), I missed one important feature of the .SECONDARY target: .SECONDARY with no prerequisites causes all targets to be treated as secondary. ... which agrees with the policy of Kbuild. Let's move it to scripts/Kbuild.include, with no prerequisites. Note: If an intermediate file is generated by $(call if_changed,...), you still need to add it to "targets" so its .*.cmd file is included. The arm/arm64 crypto files are generated by $(call cmd,shipped), so they do not need to be added to "targets", but need to be added to "clean-files" so "make clean" can properly clean them away. Signed-off-by: Masahiro Yamada