user/sven/linux.git/scripts/Kbuild.include, branch v5.4.292

kbuild: remove the target in signal traps when interrupted

2022-10-26T11:22:46Z

[ Upstream commit a7f3257da8a86b96fb9bf1bba40ae0bbd7f1885a ] When receiving some signal, GNU Make automatically deletes the target if it has already been changed by the interrupted recipe. If the target is possibly incomplete due to interruption, it must be deleted so that it will be remade from scratch on the next run of make. Otherwise, the target would remain corrupted permanently because its timestamp had already been updated. Thanks to this behavior of Make, you can stop the build any time by pressing Ctrl-C, and just run 'make' to resume it. Kbuild also relies on this feature, but it is equivalently important for any build systems that make decisions based on timestamps (if you want to support Ctrl-C reliably). However, this does not always work as claimed; Make immediately dies with Ctrl-C if its stderr goes into a pipe. [Test Makefile] foo: echo hello > $@ sleep 3 echo world >> $@ [Test Result] $ make # hit Ctrl-C echo hello > foo sleep 3 ^Cmake: *** Deleting file 'foo' make: *** [Makefile:3: foo] Interrupt $ make 2>&1 | cat # hit Ctrl-C echo hello > foo sleep 3 ^C$ # 'foo' is often left-over The reason is because SIGINT is sent to the entire process group. In this example, SIGINT kills 'cat', and 'make' writes the message to the closed pipe, then dies with SIGPIPE before cleaning the target. A typical bad scenario (as reported by [1], [2]) is to save build log by using the 'tee' command: $ make 2>&1 | tee log This can be problematic for any build systems based on Make, so I hope it will be fixed in GNU Make. The maintainer of GNU Make stated this is a long-standing issue and difficult to fix [3]. It has not been fixed yet as of writing. So, we cannot rely on Make cleaning the target. We can do it by ourselves, in signal traps. As far as I understand, Make takes care of SIGHUP, SIGINT, SIGQUIT, and SITERM for the target removal. I added the traps for them, and also for SIGPIPE just in case cmd_* rule prints something to stdout or stderr (but I did not observe an actual case where SIGPIPE was triggered). [Note 1] The trap handler might be worth explaining. rm -f $@; trap - $(sig); kill -s $(sig) $$ This lets the shell kill itself by the signal it caught, so the parent process can tell the child has exited on the signal. Generally, this is a proper manner for handling signals, in case the calling program (like Bash) may monitor WIFSIGNALED() and WTERMSIG() for WCE although this may not be a big deal here because GNU Make handles SIGHUP, SIGINT, SIGQUIT in WUE and SIGTERM in IUE. IUE - Immediate Unconditional Exit WUE - Wait and Unconditional Exit WCE - Wait and Cooperative Exit For details, see "Proper handling of SIGINT/SIGQUIT" [4]. [Note 2] Reverting 392885ee82d3 ("kbuild: let fixdep directly write to .*.cmd files") would directly address [1], but it only saves if_changed_dep. As reported in [2], all commands that use redirection can potentially leave an empty (i.e. broken) target. [Note 3] Another (even safer) approach might be to always write to a temporary file, and rename it to $@ at the end of the recipe. > $(tmp-target) mv $(tmp-target) $@ It would require a lot of Makefile changes, and result in ugly code, so I did not take it. [Note 4] A little more thoughts about a pattern rule with multiple targets (or a grouped target). %.x %.y: %.z When interrupted, GNU Make deletes both %.x and %.y, while this solution only deletes $@. Probably, this is not a big deal. The next run of make will execute the rule again to create $@ along with the other files. [1]: https://lore.kernel.org/all/YLeot94yAaM4xbMY@gmail.com/ [2]: https://lore.kernel.org/all/20220510221333.2770571-1-robh@kernel.org/ [3]: https://lists.gnu.org/archive/html/help-make/2021-06/msg00001.html [4]: https://www.cons.org/cracauer/sigint.html Fixes: 392885ee82d3 ("kbuild: let fixdep directly write to .*.cmd files") Reported-by: Ingo Molnar Reported-by: Rob Herring Signed-off-by: Masahiro Yamada Tested-by: Ingo Molnar Reviewed-by: Nicolas Schier Signed-off-by: Sasha Levin

kbuild: sink stdout from cmd for silent build

2021-07-25T12:35:11Z

[ Upstream commit 174a1dcc96429efce4ef7eb2f5c4506480da2182 ] When building with 'make -s', no output to stdout should be printed. As Arnd Bergmann reported [1], mkimage shows the detailed information of the generated images. I think this should be suppressed by the 'cmd' macro instead of by individual scripts. Insert 'exec >/dev/null;' in order to redirect stdout to /dev/null for silent builds. [Note about this implementation] 'exec >/dev/null;' may look somewhat tricky, but this has a reason. Appending '>/dev/null' at the end of command line is a common way for redirection, so I first tried this: cmd = @set -e; $(echo-cmd) $(cmd_$(1)) >/dev/null ... but it would not work if $(cmd_$(1)) itself contains a redirection. For example, cmd_wrap in scripts/Makefile.asm-generic redirects the output from the 'echo' command into the target file. It would be expanded into: echo "#include " > $@ >/dev/null Then, the target file gets empty because the string will go to /dev/null instead of $@. Next, I tried this: cmd = @set -e; $(echo-cmd) { $(cmd_$(1)); } >/dev/null The form above would be expanded into: { echo "#include " > $@; } >/dev/null This works as expected. However, it would be a syntax error if $(cmd_$(1)) is empty. When CONFIG_TRIM_UNUSED_KSYMS is disabled, $(call cmd,gen_ksymdeps) in scripts/Makefile.build would be expanded into: set -e; { ; } >/dev/null ..., which causes an syntax error. I also tried this: cmd = @set -e; $(echo-cmd) ( $(cmd_$(1)) ) >/dev/null ... but this causes a syntax error for the same reason. So, finally I adopted: cmd = @set -e; $(echo-cmd) exec >/dev/null; $(cmd_$(1)) [1]: https://lore.kernel.org/lkml/20210514135752.2910387-1-arnd@kernel.org/ Signed-off-by: Masahiro Yamada Signed-off-by: Sasha Levin

kbuild: improve cc-option to clean up all temporary files

2020-06-30T19:37:05Z

[ Upstream commit f2f02ebd8f3833626642688b2d2c6a7b3c141fa9 ] When cc-option and friends evaluate compiler flags, the temporary file $$TMP is created as an output object, and automatically cleaned up. The actual file path of $$TMP is ..tmp, here is the process ID of $(shell ...) invoked from cc-option. (Please note $$$$ is the escape sequence of $$). Such garbage files are cleaned up in most cases, but some compiler flags create additional output files. For example, -gsplit-dwarf creates a .dwo file. When CONFIG_DEBUG_INFO_SPLIT=y, you will see a bunch of ..dwo files left in the top of build directories. You may not notice them unless you do 'ls -a', but the garbage files will increase every time you run 'make'. This commit changes the temporary object path to .tmp_/tmp, and removes .tmp_ directory when exiting. Separate build artifacts such as *.dwo will be cleaned up all together because their file paths are usually determined based on the base name of the object. Another example is -ftest-coverage, which outputs the coverage data into .gcno Signed-off-by: Masahiro Yamada Signed-off-by: Sasha Levin

kbuild: remove *.tmp file when filechk fails

2020-02-24T07:36:49Z

[ Upstream commit 88fe89a47153facd8cb2d06d5c8727f7224c43c2 ] Bartosz Golaszewski reports that when "make {menu,n,g,x}config" fails due to missing packages, a temporary file is left over, which is not ignored by git. For example, if GTK+ is not installed: $ make gconfig * * Unable to find the GTK+ installation. Please make sure that * the GTK+ 2.0 development package is correctly installed. * You need gtk+-2.0 gmodule-2.0 libglade-2.0 * scripts/kconfig/Makefile:208: recipe for target 'scripts/kconfig/gconf-cfg' failed make[1]: *** [scripts/kconfig/gconf-cfg] Error 1 Makefile:567: recipe for target 'gconfig' failed make: *** [gconfig] Error 2 $ git status HEAD detached at v5.4 Untracked files: (use "git add ..." to include in what will be committed) scripts/kconfig/gconf-cfg.tmp nothing added to commit but untracked files present (use "git add" to track) This is because the check scripts are run with filechk, which misses to clean up the temporary file on failure. When the line { $(filechk_$(1)); } > $@.tmp; ... fails, it exits immediately due to the 'set -e'. Use trap to make sure to delete the temporary file on exit. For extra safety, I replaced $@.tmp with $(dot-target).tmp to make it a hidden file. Reported-by: Bartosz Golaszewski Signed-off-by: Masahiro Yamada Signed-off-by: Sasha Levin

kbuild: remove ar-option and KBUILD_ARFLAGS

2019-10-01T00:20:33Z

Commit 40df759e2b9e ("kbuild: Fix build with binutils <= 2.19") introduced ar-option and KBUILD_ARFLAGS to deal with old binutils. According to Documentation/process/changes.rst, the current minimal supported version of binutils is 2.21 so you can assume the 'D' option is always supported. Not only GNU ar but also llvm-ar supports it. With the 'D' option hard-coded, there is no more user of ar-option or KBUILD_ARFLAGS. Signed-off-by: Masahiro Yamada Reviewed-by: Nick Desaulniers Tested-by: Nick Desaulniers

kbuild: remove unused objectify macro

2019-07-27T03:18:19Z

Commit 415008af3219 ("docs-rst: convert lsm from DocBook to ReST") removed the last users of this macro. Signed-off-by: Masahiro Yamada

kbuild: remove unused hostcc-option

2019-07-17T13:37:51Z

We can re-add this whenever it is needed. At this moment, it is unused. Signed-off-by: Masahiro Yamada

Merge tag 'kbuild-v5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

2019-07-12T23:03:16Z

Pull Kbuild updates from Masahiro Yamada: - remove headers_{install,check}_all targets - remove unreasonable 'depends on !UML' from CONFIG_SAMPLES - re-implement 'make headers_install' more cleanly - add new header-test-y syntax to compile-test headers - compile-test exported headers to ensure they are compilable in user-space - compile-test headers under include/ to ensure they are self-contained - remove -Waggregate-return, -Wno-uninitialized, -Wno-unused-value flags - add -Werror=unknown-warning-option for Clang - add 128-bit built-in types support to genksyms - fix missed rebuild of modules.builtin - propagate 'No space left on device' error in fixdep to Make - allow Clang to use its integrated assembler - improve some coccinelle scripts - add a new flag KBUILD_ABS_SRCTREE to request Kbuild to use absolute path for $(srctree). - do not ignore errors when compression utility is missing - misc cleanups * tag 'kbuild-v5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (49 commits) kbuild: use -- separater intead of $(filter-out ...) for cc-cross-prefix kbuild: Inform user to pass ARCH= for make mrproper kbuild: fix compression errors getting ignored kbuild: add a flag to force absolute path for srctree kbuild: replace KBUILD_SRCTREE with boolean building_out_of_srctree kbuild: remove src and obj from the top Makefile scripts/tags.sh: remove unused environment variables from comments scripts/tags.sh: drop SUBARCH support for ARM kbuild: compile-test kernel headers to ensure they are self-contained kheaders: include only headers into kheaders_data.tar.xz kheaders: remove meaningless -R option of 'ls' kbuild: support header-test-pattern-y kbuild: do not create wrappers for header-test-y kbuild: compile-test exported headers to ensure they are self-contained init/Kconfig: add CONFIG_CC_CAN_LINK kallsyms: exclude kasan local symbols on s390 kbuild: add more hints about SUBDIRS replacement coccinelle: api/stream_open: treat all wait_.*() calls as blocking coccinelle: put_device: Add a cast to an expression for an assignment coccinelle: put_device: Adjust a message construction ...

kbuild: use -- separater intead of $(filter-out ...) for cc-cross-prefix

2019-07-11T14:34:52Z

arch/mips/Makefile passes prefixes that start with '-' to cc-cross-prefix when $(tool-archpref) evaluates to the empty string. They are filtered-out before the $(shell ...) invocation. Otherwise, 'command -v' would be confused. $ command -v -linux-gcc bash: command: -l: invalid option command: usage: command [-pVv] command [arg ...] Since commit 913ab9780fc0 ("kbuild: use more portable 'command -v' for cc-cross-prefix"), cc-cross-prefix throws away the stderr output, so the console is not polluted in any way. This is not a big deal in practice, but I see a slightly better taste in adding '--' to teach it that '-linux-gcc' is an argument instead of a command option. This will cause extra forking of subshell, but it will not be noticeable performance regression. Signed-off-by: Masahiro Yamada

kbuild: save $(strip ...) for calling if_changed and friends

2019-07-01T01:03:40Z

The string returned by $(filter-out ...) does not contain any leading or trailing spaces. With the previous commit, 'any-prereq' no longer contains any excessive spaces. Nor does 'cmd-check' since it expands to a $(filter-out ...) call. So, only the space that matters is the one between 'any-prereq' and 'cmd-check'. By removing it from the code, we can save $(strip ...) evaluation. This refactoring is possible because $(any-prereq)$(cmd-check) is only passed to the first argument of $(if ...), so we are only interested in whether or not it is empty. Signed-off-by: Masahiro Yamada