user/sven/linux.git/scripts/Kbuild.include, branch v4.18.11

kbuild: add .DELETE_ON_ERROR special target

2018-09-26T06:39:23Z

[ Upstream commit 9c2af1c7377a8a6ef86e5cabf80978f3dbbb25c0 ] If Make gets a fatal signal while a shell is executing, it may delete the target file that the recipe was supposed to update. This is needed to make sure that it is remade from scratch when Make is next run; if Make is interrupted after the recipe has begun to write the target file, it results in an incomplete file whose time stamp is newer than that of the prerequisites files. Make automatically deletes the incomplete file on interrupt unless the target is marked .PRECIOUS. The situation is just the same as when the shell fails for some reasons. Usually when a recipe line fails, if it has changed the target file at all, the file is corrupted, or at least it is not completely updated. Yet the file’s time stamp says that it is now up to date, so the next time Make runs, it will not try to update that file. However, Make does not cater to delete the incomplete target file in this case. We need to add .DELETE_ON_ERROR somewhere in the Makefile to request it. scripts/Kbuild.include seems a suitable place to add it because it is included from almost all sub-makes. Please note .DELETE_ON_ERROR is not effective for phony targets. The external module building should never ever touch the kernel tree. The following recipe fails if include/generated/autoconf.h is missing. However, include/config/auto.conf is not deleted since it is a phony target. PHONY += include/config/auto.conf include/config/auto.conf: $(Q)test -e include/generated/autoconf.h -a -e $@ || ( \ echo >&2; \ echo >&2 " ERROR: Kernel configuration is invalid."; \ echo >&2 " include/generated/autoconf.h or $@ are missing.";\ echo >&2 " Run 'make oldconfig && make prepare' on kernel src to fix it."; \ echo >&2 ; \ /bin/false) Signed-off-by: Masahiro Yamada Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

kbuild: do not drop -I without parameter

2018-07-06T13:04:02Z

The comment line for addtree says "skip if -I has no parameter". What it actually does is "drop if -I has no parameter". For example, if you have the compiler flag '-I foo' (a space between), it will be converted to 'foo'. This completely changes the meaning. What we want is, "do nothing" for -I without parameter so that '-I foo' is kept as-is. Signed-off-by: Masahiro Yamada

kbuild: remove kbuild cache

2018-05-28T18:28:58Z

The kbuild cache was introduced to remember the result of shell commands, some of which are expensive to compute, such as $(call cc-option,...). However, this turned out not so clever as I had first expected. Actually, it is problematic. For example, "$(CC) -print-file-name" is cached. If the compiler is updated, the stale search path causes build error, which is difficult to figure out. Another problem scenario is cache files could be touched while install targets are running under the root permission. We can patch them if desired, but the build infrastructure is getting uglier and uglier. Now, we are going to move compiler flag tests to the configuration phase. If this is completed, the result of compiler tests will be naturally cached in the .config file. We will not have performance issues of incremental building since this testing only happens at Kconfig time. To start this work with a cleaner code base, remove the kbuild cache first. Revert the following commits: Commit 9a234a2e3843 ("kbuild: create directory for make cache only when necessary") Commit e17c400ae194 ("kbuild: shrink .cache.mk when it exceeds 1000 lines") Commit 4e56207130ed ("kbuild: Cache a few more calls to the compiler") Commit 3298b690b21c ("kbuild: Add a cache for generated variables") Signed-off-by: Masahiro Yamada Reviewed-by: Kees Cook

kbuild: do not display CHK for filechk

2018-05-28T09:25:21Z

filechk displays two short logs; CHK for creating a temporary file, and UPD for really updating the target. IMHO, the build system can be quiet when the target file has not been updated. Signed-off-by: Masahiro Yamada Reviewed-by: Sam Ravnborg

Kbuild: fix # escaping in .cmd files for future Make

2018-04-10T15:03:02Z

I tried building using a freshly built Make (4.2.1-69-g8a731d1), but already the objtool build broke with orc_dump.c: In function ‘orc_dump’: orc_dump.c:106:2: error: ‘elf_getshnum’ is deprecated [-Werror=deprecated-declarations] if (elf_getshdrnum(elf, &nr_sections)) { Turns out that with that new Make, the backslash was not removed, so cpp didn't see a #include directive, grep found nothing, and -DLIBELF_USE_DEPRECATED was wrongly put in CFLAGS. Now, that new Make behaviour is documented in their NEWS file: * WARNING: Backward-incompatibility! Number signs (#) appearing inside a macro reference or function invocation no longer introduce comments and should not be escaped with backslashes: thus a call such as: foo := $(shell echo '#') is legal. Previously the number sign needed to be escaped, for example: foo := $(shell echo '\#') Now this latter will resolve to "\#". If you want to write makefiles portable to both versions, assign the number sign to a variable: C := \# foo := $(shell echo '$C') This was claimed to be fixed in 3.81, but wasn't, for some reason. To detect this change search for 'nocomment' in the .FEATURES variable. This also fixes up the two make-cmd instances to replace # with $(pound) rather than with \#. There might very well be other places that need similar fixup in preparation for whatever future Make release contains the above change, but at least this builds an x86_64 defconfig with the new make. Link: https://bugzilla.kernel.org/show_bug.cgi?id=197847 Cc: Randy Dunlap Signed-off-by: Rasmus Villemoes Signed-off-by: Masahiro Yamada

kbuild: move include/config/ksym/* to include/ksym/*

2018-03-25T17:01:23Z

The idea of using fixdep was inspired by Kconfig, but autoksyms belongs to a different group. So, I want to move those touched files under include/config/ksym/ to include/ksym/. The directory include/ksym/ can be removed by 'make clean' because it is meaningless for the external module building. Signed-off-by: Masahiro Yamada Acked-by: Nicolas Pitre

kbuild: simplify ld-option implementation

2018-03-25T17:01:20Z

Currently, linker options are tested by the coordination of $(CC) and $(LD) because $(LD) needs some object to link. As commit 86a9df597cdd ("kbuild: fix linker feature test macros when cross compiling with Clang") addressed, we need to make sure $(CC) and $(LD) agree the underlying architecture of the passed object. This could be a bit complex when we combine tools from different groups. For example, we can use clang for $(CC), but we still need to rely on GCC toolchain for $(LD). So, I was searching for a way of standalone testing of linker options. A trick I found is to use '-v'; this not only prints the version string, but also tests if the given option is recognized. If a given option is supported, $ aarch64-linux-gnu-ld -v --fix-cortex-a53-843419 GNU ld (Linaro_Binutils-2017.11) 2.28.2.20170706 $ echo $? 0 If unsupported, $ aarch64-linux-gnu-ld -v --fix-cortex-a53-843419 GNU ld (crosstool-NG linaro-1.13.1-4.7-2013.04-20130415 - Linaro GCC 2013.04) 2.23.1 aarch64-linux-gnu-ld: unrecognized option '--fix-cortex-a53-843419' aarch64-linux-gnu-ld: use the --help option for usage information $ echo $? 1 Gold works likewise. $ aarch64-linux-gnu-ld.gold -v --fix-cortex-a53-843419 GNU gold (Linaro_Binutils-2017.11 2.28.2.20170706) 1.14 masahiro@pug:~/ref/linux$ echo $? 0 $ aarch64-linux-gnu-ld.gold -v --fix-cortex-a53-999999 GNU gold (Linaro_Binutils-2017.11 2.28.2.20170706) 1.14 aarch64-linux-gnu-ld.gold: --fix-cortex-a53-999999: unknown option aarch64-linux-gnu-ld.gold: use the --help option for usage information $ echo $? 1 LLD too. $ ld.lld -v --gc-sections LLD 7.0.0 (http://llvm.org/git/lld.git 4a0e4190e74cea19f8a8dc625ccaebdf8b5d1585) (compatible with GNU linkers) $ echo $? 0 $ ld.lld -v --fix-cortex-a53-843419 LLD 7.0.0 (http://llvm.org/git/lld.git 4a0e4190e74cea19f8a8dc625ccaebdf8b5d1585) (compatible with GNU linkers) $ echo $? 0 $ ld.lld -v --fix-cortex-a53-999999 ld.lld: error: unknown argument: --fix-cortex-a53-999999 LLD 7.0.0 (http://llvm.org/git/lld.git 4a0e4190e74cea19f8a8dc625ccaebdf8b5d1585) (compatible with GNU linkers) $ echo $? 1 Signed-off-by: Masahiro Yamada Tested-by: Nick Desaulniers

kbuild: Improve portability of some sed invocations

2018-03-25T17:01:18Z

* Use BREs where EREs aren't necessary. * Pass -E instead of -r to use EREs. This will be standardized in the next POSIX revision[0]. GNU sed supports this since 4.2 (May 2009), and busybox since 1.22.0 (Jan 2014). * Use the [:space:] character class instead of ` \t` in bracket expressions. In bracket expressions, POSIX says that loses its special meaning, so a conforming implementation cannot expand \t to [1]. * In BREs, use interval expressions (\{n,m\}) instead of non-standard features like \+ and \?. * Use a loop instead of -s flag. There are still plenty of other cases of non-standard sed invocations (use of ERE features in BREs, in-place editing), but this fixes some core ones. [0] http://austingroupbugs.net/view.php?id=528 [1] http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap09.html#tag_09_03_05 Signed-off-by: Michael Forney Signed-off-by: Masahiro Yamada

kbuild: create directory for make cache only when necessary

2017-11-16T00:07:32Z

Currently, the existence of $(dir $(make-cache)) is always checked, and created if it is missing. We can avoid unnecessary system calls by some tricks. [1] If KBUILD_SRC is unset, we are building in the source tree. The output directory checks can be entirely skipped. [2] If at least one cache data is found, it means the cache file was included. Obviously its directory exists. Skip "mkdir -p". [3] If Makefile does not contain any call of __run-and-store, it will not create a cache file. No need to create its directory. [4] The "mkdir -p" should be only invoked by the first call of __run-and-store Signed-off-by: Masahiro Yamada Reviewed-by: Douglas Anderson

kbuild: fix linker feature test macros when cross compiling with Clang

2017-11-13T13:54:24Z

I was not seeing my linker flags getting added when using ld-option when cross compiling with Clang. Upon investigation, this seems to be due to a difference in how GCC vs Clang handle cross compilation. GCC is configured at build time to support one backend, that is implicit when compiling. Clang is explicit via the use of `-target ` and ships with all supported backends by default. GNU Make feature test macros that compile then link will always fail when cross compiling with Clang unless Clang's triple is passed along to the compiler. For example: $ clang -x c /dev/null -c -o temp.o $ aarch64-linux-android/bin/ld -E temp.o aarch64-linux-android/bin/ld: unknown architecture of input file `temp.o' is incompatible with aarch64 output aarch64-linux-android/bin/ld: warning: cannot find entry symbol _start; defaulting to 0000000000400078 $ echo $? 1 $ clang -target aarch64-linux-android- -x c /dev/null -c -o temp.o $ aarch64-linux-android/bin/ld -E temp.o aarch64-linux-android/bin/ld: warning: cannot find entry symbol _start; defaulting to 00000000004002e4 $ echo $? 0 This causes conditional checks that invoke $(CC) without the target triple, then $(LD) on the result, to always fail. Suggested-by: Masahiro Yamada Signed-off-by: Nick Desaulniers Reviewed-by: Matthias Kaehlcke Signed-off-by: Masahiro Yamada