kernel/git/stable/linux.git/Documentation/kbuild, branch linux-4.19.y

kbuild: support LLVM=1 to switch the default tools to Clang/LLVM

2020-09-26T16:01:32+00:00

commit a0d1c951ef08ed24f35129267e3595d86f57f5d3 upstream. As Documentation/kbuild/llvm.rst implies, building the kernel with a full set of LLVM tools gets very verbose and unwieldy. Provide a single switch LLVM=1 to use Clang and LLVM tools instead of GCC and Binutils. You can pass it from the command line or as an environment variable. Please note LLVM=1 does not turn on the integrated assembler. You need to pass LLVM_IAS=1 to use it. When the upstream kernel is ready for the integrated assembler, I think we can make it default. We discussed what we need, and we agreed to go with a simple boolean flag that switches both target and host tools: https://lkml.org/lkml/2020/3/28/494 https://lkml.org/lkml/2020/4/3/43 Some items discussed, but not adopted: - LLVM_DIR When multiple versions of LLVM are installed, I just thought supporting LLVM_DIR=/path/to/my/llvm/bin/ might be useful. CC = $(LLVM_DIR)clang LD = $(LLVM_DIR)ld.lld ... However, we can handle this by modifying PATH. So, we decided to not do this. - LLVM_SUFFIX Some distributions (e.g. Debian) package specific versions of LLVM with naming conventions that use the version as a suffix. CC = clang$(LLVM_SUFFIX) LD = ld.lld(LLVM_SUFFIX) ... will allow a user to pass LLVM_SUFFIX=-11 to use clang-11 etc., but the suffixed versions in /usr/bin/ are symlinks to binaries in /usr/lib/llvm-#/bin/, so this can also be handled by PATH. Signed-off-by: Masahiro Yamada Reviewed-by: Nathan Chancellor Tested-by: Nathan Chancellor # build Tested-by: Nick Desaulniers Reviewed-by: Nick Desaulniers Signed-off-by: Nick Desaulniers [nd: conflict in exported vars list from not backporting commit e83b9f55448a ("kbuild: add ability to generate BTF type info for vmlinux")] [nd: hunk against Documentation/kbuild/kbuild.rst dropped due to not backporting commit cd238effefa2 ("docs: kbuild: convert docs to ReST and rename to *.rst")] Signed-off-by: Greg Kroah-Hartman

kbuild: replace AS=clang with LLVM_IAS=1

2020-09-26T16:01:32+00:00

commit 7e20e47c70f810d678d02941fa3c671209c4ca97 upstream. The 'AS' variable is unused for building the kernel. Only the remaining usage is to turn on the integrated assembler. A boolean flag is a better fit for this purpose. AS=clang was added for experts. So, I replaced it with LLVM_IAS=1, breaking the backward compatibility. Suggested-by: Nick Desaulniers Signed-off-by: Masahiro Yamada Reviewed-by: Nathan Chancellor Reviewed-by: Nick Desaulniers Signed-off-by: Nick Desaulniers Signed-off-by: Greg Kroah-Hartman

Documentation/llvm: fix the name of llvm-size

2020-09-26T16:01:31+00:00

commit 0f44fbc162b737ff6251ae248184390ae2279fee upstream. The tool is called llvm-size, not llvm-objsize. Fixes: fcf1b6a35c16 ("Documentation/llvm: add documentation on building w/ Clang/LLVM") Signed-off-by: Fangrui Song Reviewed-by: Nick Desaulniers Reviewed-by: Nathan Chancellor Signed-off-by: Masahiro Yamada Signed-off-by: Nick Desaulniers Signed-off-by: Greg Kroah-Hartman

Documentation/llvm: add documentation on building w/ Clang/LLVM

2020-09-26T16:01:31+00:00

commit fcf1b6a35c16ac500fa908a4022238e5d666eabf upstream. added to kbuild documentation. Provides more official info on building kernels with Clang and LLVM than our wiki. Suggested-by: Kees Cook Reviewed-by: Kees Cook Reviewed-by: Nathan Chancellor Reviewed-by: Sedat Dilek Signed-off-by: Nick Desaulniers Signed-off-by: Masahiro Yamada [nd: hunk against Documentation/kbuild/index.rst dropped due to not backporting commit cd238effefa2 ("docs: kbuild: convert docs to ReST and rename to *.rst")] Signed-off-by: Greg Kroah-Hartman

kbuild: Fix LOADLIBES rename in Documentation/kbuild/makefiles.txt

2018-08-22T14:21:42+00:00

Fixes: 8377bd2b9ee1 ("kbuild: Rename HOST_LOADLIBES to KBUILD_HOSTLDLIBS") Signed-off-by: Michal Suchanek Acked-by: Laura Abbott Signed-off-by: Masahiro Yamada

kconfig: report recursive dependency involving 'imply'

2018-08-22T14:21:39+00:00

Currently, Kconfig does not complain about the recursive dependency where 'imply' keywords are involved. [Test Code] config A bool "a" config B bool "b" imply A depends on A In the code above, Kconfig cannot calculate the symbol values correctly due to the circular dependency. For example, allyesconfig followed by syncconfig results in an odd behavior because CONFIG_B becomes visible in syncconfig. $ make allyesconfig scripts/kconfig/conf --allyesconfig Kconfig # # configuration written to .config # $ cat .config # # Automatically generated file; DO NOT EDIT. # Main menu # CONFIG_A=y $ make syncconfig scripts/kconfig/conf --syncconfig Kconfig * * Restart config... * * * Main menu * a (A) [Y/n/?] y b (B) [N/y/?] (NEW) To detect this correctly, sym_check_expr_deps() should recurse to not only sym->rev_dep.expr but also sym->implied.expr . At this moment, sym_check_print_recursive() cannot distinguish 'select' and 'imply' since it does not know the precise context where the recursive dependency has been hit. This will be solved by the next commit. In fact, even the document and the unit-test are confused. Using 'imply' does not solve recursive dependency since 'imply' addresses the unmet direct dependency, which 'select' could cause. Signed-off-by: Masahiro Yamada Tested-by: Dirk Gouders

Merge tag 'kconfig-v4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

2018-08-15T19:50:10+00:00

Pull Kconfig updates from Masahiro Yamada: - show clearer error messages where pkg-config is needed, but not installed - rename SYMBOL_AUTO to SYMBOL_NO_WRITE to reflect its semantics - create all necessary directories by Kconfig tool itself instead of Makefile - update the .config unconditionally when syncconfig is invoked - use 'include' directive instead of '-include' where include/config/{auto,tristate}.conf is mandatory - do not try to update the .config when running install targets - add .DELETE_ON_ERROR to delete partially updated files - misc cleanups and fixes * tag 'kconfig-v4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: kconfig: remove P_ENV property type kconfig: remove unused sym_get_env_prop() function kconfig: fix the rule of mainmenu_stmt symbol init/Kconfig: Use short unix-style option instead of --longname Kbuild: Makefile.modbuiltin: include auto.conf and tristate.conf mandatory kbuild: remove auto.conf from prerequisite of phony targets kbuild: do not update config for 'make kernelrelease' kbuild: do not update config when running install targets kbuild: add .DELETE_ON_ERROR special target kbuild: use 'include' directive to load auto.conf from top Makefile kconfig: allow all config targets to write auto.conf if missing kconfig: make syncconfig update .config regardless of sym_change_count kconfig: create directories needed for syncconfig by itself kconfig: remove unneeded directory generation from local*config kconfig: split out useful helpers in confdata.c kconfig: rename file_write_dep and move it to confdata.c kconfig: fix typos in description of "choice" in kconfig-language.txt kconfig: handle format string before calling conf_message_callback() kconfig: rename SYMBOL_AUTO to SYMBOL_NO_WRITE kconfig: check for pkg-config on make {menu,n,g,x}config

kconfig: fix typos in description of "choice" in kconfig-language.txt

2018-07-25T14:25:28+00:00

Fix a couple of punctuation "typos" in the description of the "choice" keyword. Signed-off-by: Randy Dunlap Signed-off-by: Masahiro Yamada

kbuild: if_changed: document single use per target limitation

2018-07-20T21:50:32+00:00

Users of if_changed could easily feel invited to use it to divide a recipe into parts like: a: prereq FORCE $(call if_changed,do_a) $(call if_changed,do_b) But this is problematic, because if_changed should not be used more than once per target: in the above example, if_changed stores the command-line of the given command in .a.cmd and when a is up-to-date with respect to prereq, the file .a.cmd contains the command-line for the last command executed, i.e. do_b. When the recipe is then executed again, without any change of prerequisites, the command-line check for do_a will fail, do_a will be executed and stored in .a.cmd. The next check, however, will still see the old content (the file isn't re-read) and if_changed will skip do_b, because the command-line test will not recognize a change. On the next execution of the recipe the roles will flip: do_a is OK but do_b not and it will be executed. And so on... Signed-off-by: Dirk Gouders Signed-off-by: Masahiro Yamada

kbuild: Use HOST*FLAGS options from the command line

2018-07-17T16:18:05+00:00

Now that we have the rename in place, reuse the HOST*FLAGS options as something that can be set from the command line and included with the rest of the flags. Signed-off-by: Laura Abbott Signed-off-by: Masahiro Yamada