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Kbuild descends into a directory by either 'y' or 'm', but there is an
important difference.
Kbuild combines the built-in objects into built-in.a in each directory.
The built-in.a in the directory visited by obj-y is merged into the
built-in.a in the parent directory. This merge happens recursively
when Kbuild is ascending back towards the top directory, then built-in
objects are linked into vmlinux eventually. This works properly only
when the Makefile specifying obj-y is reachable by the chain of obj-y.
On the other hand, Kbuild does not take built-in.a from the directory
visited by obj-m. This it, all the objects in that directory are
supposed to be modular. If Kbuild descends into a directory by obj-m,
but the Makefile in the sub-directory specifies obj-y, those objects
are just left orphan.
The current statement "Kbuild only uses this information to decide that
it needs to visit the directory" is misleading. Clarify the difference.
Reported-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Johan Hovold <johan@kernel.org>
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Since commit 84af7a6194e4 ("checkpatch: kconfig: prefer 'help' over
'---help---'"), scripts/checkpatch.pl warns the use of ---help---.
Kconfig still supports ---help---, but new code should avoid using it.
Let's stop advertising it in documentation.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
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There are both positive and negative options about this feature.
At first, I thought it was a good idea, but actually Linus stated a
negative opinion (https://lkml.org/lkml/2019/9/29/227). I admit it
is ugly and annoying.
The baseline I'd like to keep is the compile-test of uapi headers.
(Otherwise, kernel developers have no way to ensure the correctness
of the exported headers.)
I will maintain a small build rule in usr/include/Makefile.
Remove the other header test functionality.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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Since commit 040fcc819a2e ("kbuild: improved modversioning support for
external modules"), the external module build reads Module.symvers in
the directory of the module itself, then dumps symbols back into it.
It accumulates stale symbols in the file when you build an external
module incrementally.
The idea behind it was, as the commit log explained, you can copy
Modules.symvers from one module to another when you need to pass symbol
information between two modules. However, the manual copy of the file
sounds questionable to me, and containing stale symbols is a downside.
Some time later, commit 0d96fb20b7ed ("kbuild: Add new Kbuild variable
KBUILD_EXTRA_SYMBOLS") introduced a saner approach.
So, this commit removes the former one. Going forward, the external
module build dumps symbols into Module.symvers to be carried via
KBUILD_EXTRA_SYMBOLS, but never reads it automatically.
With the -I option removed, there is no one to set the external_module
flag unless KBUILD_EXTRA_SYMBOLS is passed. Now the -i option does it
instead.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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Pull module fixes from Jessica Yu:
"Code cleanups and kbuild/namespace related fixups from Masahiro.
Most importantly, it fixes a namespace-related modpost issue for
external module builds
- Fix broken external module builds due to a modpost bug in
read_dump(), where the namespace was not being strdup'd and
sym->namespace would be set to bogus data.
- Various namespace-related kbuild fixes and cleanups thanks to
Masahiro Yamada"
* tag 'modules-for-v5.4-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux:
doc: move namespaces.rst from kbuild/ to core-api/
nsdeps: make generated patches independent of locale
nsdeps: fix hashbang of scripts/nsdeps
kbuild: fix build error of 'make nsdeps' in clean tree
module: rename __kstrtab_ns_* to __kstrtabns_* to avoid symbol conflict
modpost: fix broken sym->namespace for external module builds
module: swap the order of symbol.namespace
scripts: add_namespace: Fix coccicheck failed
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We discussed a better location for this file, and agreed that
core-api/ is a good fit. Rename it to symbol-namespaces.rst
for disambiguation, and also add it to index.rst and MAINTAINERS.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Matthias Maennich <maennich@google.com>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
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In commit 43d8ce9d65a5 ("Provide in-kernel headers to make
extending kernel easier") a new mechanism was introduced, for kernels
>=5.2, which embeds the kernel headers in the kernel image or a module
and exposes them in procfs for use by userland tools.
The archive containing the header files has nondeterminism caused by
header files metadata. This patch normalizes the metadata and utilizes
KBUILD_BUILD_TIMESTAMP if provided and otherwise falls back to the
default behaviour.
In commit f7b101d33046 ("kheaders: Move from proc to sysfs") it was
modified to use sysfs and the script for generation of the archive was
renamed to what is being patched.
Signed-off-by: Dmitry Goldin <dgoldin+lkml@protonmail.ch>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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Capitalize the first word in the sentence.
Use obj-m instead of obj-y. obj-y still works, but we have no built-in
objects in external module builds. So, obj-m is better IMHO.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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Minor formatting fixup.
Fixes: cd238effefa2 ("docs: kbuild: convert docs to ReST and rename to *.rst")
Signed-off-by: Alex Gaynor <alex.gaynor@gmail.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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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 <yamada.masahiro@socionext.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
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Pull modules updates from Jessica Yu:
"The main bulk of this pull request introduces a new exported symbol
namespaces feature. The number of exported symbols is increasingly
growing with each release (we're at about 31k exports as of 5.3-rc7)
and we currently have no way of visualizing how these symbols are
"clustered" or making sense of this huge export surface.
Namespacing exported symbols allows kernel developers to more
explicitly partition and categorize exported symbols, as well as more
easily limiting the availability of namespaced symbols to other parts
of the kernel. For starters, we have introduced the USB_STORAGE
namespace to demonstrate the API's usage. I have briefly summarized
the feature and its main motivations in the tag below.
Summary:
- Introduce exported symbol namespaces.
This new feature allows subsystem maintainers to partition and
categorize their exported symbols into explicit namespaces. Module
authors are now required to import the namespaces they need.
Some of the main motivations of this feature include: allowing
kernel developers to better manage the export surface, allow
subsystem maintainers to explicitly state that usage of some
exported symbols should only be limited to certain users (think:
inter-module or inter-driver symbols, debugging symbols, etc), as
well as more easily limiting the availability of namespaced symbols
to other parts of the kernel.
With the module import requirement, it is also easier to spot the
misuse of exported symbols during patch review.
Two new macros are introduced: EXPORT_SYMBOL_NS() and
EXPORT_SYMBOL_NS_GPL(). The API is thoroughly documented in
Documentation/kbuild/namespaces.rst.
- Some small code and kbuild cleanups here and there"
* tag 'modules-for-v5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux:
module: Remove leftover '#undef' from export header
module: remove unneeded casts in cmp_name()
module: move CONFIG_UNUSED_SYMBOLS to the sub-menu of MODULES
module: remove redundant 'depends on MODULES'
module: Fix link failure due to invalid relocation on namespace offset
usb-storage: export symbols in USB_STORAGE namespace
usb-storage: remove single-use define for debugging
docs: Add documentation for Symbol Namespaces
scripts: Coccinelle script for namespace dependencies.
modpost: add support for generating namespace dependencies
export: allow definition default namespaces in Makefiles or sources
module: add config option MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS
modpost: add support for symbol namespaces
module: add support for symbol namespaces.
export: explicitly align struct kernel_symbol
module: support reading multiple values per modinfo tag
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Pull Kbuild updates from Masahiro Yamada:
- add modpost warn exported symbols marked as 'static' because 'static'
and EXPORT_SYMBOL is an odd combination
- break the build early if gold linker is used
- optimize the Bison rule to produce .c and .h files by a single
pattern rule
- handle PREEMPT_RT in the module vermagic and UTS_VERSION
- warn CONFIG options leaked to the user-space except existing ones
- make single targets work properly
- rebuild modules when module linker scripts are updated
- split the module final link stage into scripts/Makefile.modfinal
- fix the missed error code in merge_config.sh
- improve the error message displayed on the attempt of the O= build in
unclean source tree
- remove 'clean-dirs' syntax
- disable -Wimplicit-fallthrough warning for Clang
- add CONFIG_CC_OPTIMIZE_FOR_SIZE_O3 for ARC
- remove ARCH_{CPP,A,C}FLAGS variables
- add $(BASH) to run bash scripts
- change *CFLAGS_<basetarget>.o to take the relative path to $(obj)
instead of the basename
- stop suppressing Clang's -Wunused-function warnings when W=1
- fix linux/export.h to avoid genksyms calculating CRC of trimmed
exported symbols
- misc cleanups
* tag 'kbuild-v5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (63 commits)
genksyms: convert to SPDX License Identifier for lex.l and parse.y
modpost: use __section in the output to *.mod.c
modpost: use MODULE_INFO() for __module_depends
export.h, genksyms: do not make genksyms calculate CRC of trimmed symbols
export.h: remove defined(__KERNEL__), which is no longer needed
kbuild: allow Clang to find unused static inline functions for W=1 build
kbuild: rename KBUILD_ENABLE_EXTRA_GCC_CHECKS to KBUILD_EXTRA_WARN
kbuild: refactor scripts/Makefile.extrawarn
merge_config.sh: ignore unwanted grep errors
kbuild: change *FLAGS_<basetarget>.o to take the path relative to $(obj)
modpost: add NOFAIL to strndup
modpost: add guid_t type definition
kbuild: add $(BASH) to run scripts with bash-extension
kbuild: remove ARCH_{CPP,A,C}FLAGS
kbuild,arc: add CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3 for ARC
kbuild: Do not enable -Wimplicit-fallthrough for clang for now
kbuild: clean up subdir-ymn calculation in Makefile.clean
kbuild: remove unneeded '+' marker from cmd_clean
kbuild: remove clean-dirs syntax
kbuild: check clean srctree even earlier
...
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In the Distribution Kernels track at Linux Plumbers Conference there
was some discussion around the difficulty of making kernel builds
reproducible.
This is a solved problem, but the solutions don't appear to be
documented in one place. This document lists the issues I know about
and the settings needed to ensure reproducibility.
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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Describe using Symbol Namespaces from a perspective of a user. I.e.
module authors or subsystem maintainers.
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Matthias Maennich <maennich@google.com>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
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Add support for symbols that are exported into namespaces. For that,
extract any namespace suffix from the symbol name. In addition, emit a
warning whenever a module refers to an exported symbol without
explicitly importing the namespace that it is defined in. This patch
consistently adds the namespace suffix to symbol names exported into
Module.symvers.
Example warning emitted by modpost in case of the above violation:
WARNING: module ums-usbat uses symbol usb_stor_resume from namespace
USB_STORAGE, but does not import it.
Co-developed-by: Martijn Coenen <maco@android.com>
Signed-off-by: Martijn Coenen <maco@android.com>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Matthias Maennich <maennich@google.com>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
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KBUILD_ENABLE_EXTRA_GCC_CHECKS started as a switch to add extra warning
options for GCC, but now it is a historical misnomer since we use it
also for Clang, DTC, and even kernel-doc.
Rename it to more sensible, shorter KBUILD_EXTRA_WARN.
For the backward compatibility, KBUILD_ENABLE_EXTRA_GCC_CHECKS is still
supported (but not advertised in the documentation).
I also fixed up 'make help', and updated the documentation.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Sedat Dilek <sedat.dilek@gmail.com>
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These flags were added by commit 61754c18752f ("kbuild: Allow arch
Makefiles to override {cpp,ld,c}flags") to allow ARC to override -O2.
We did not see any other usage after all. Now that ARC switched to
CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3, there is no more user of
these variables.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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The only the difference between clean-files and clean-dirs is the -r
option passed to the 'rm' command.
You can always pass -r, and then remove the clean-dirs syntax.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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Commit 055efab3120b ("kbuild: drop support for cc-ldoption") correctly
removed the cc-ldoption from Documentation/kbuild/makefiles.txt, but
commit cd238effefa2 ("docs: kbuild: convert docs to ReST and rename
to *.rst") revived it. I guess it was a rebase mistake.
Remove it again.
Fixes: cd238effefa2 ("docs: kbuild: convert docs to ReST and rename to *.rst")
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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I see the following warnings when I open this document with a ReST
viewer, retext:
/home/masahiro/ref/linux/Documentation/kbuild/makefiles.rst:1142: (WARNING/2) Inline emphasis start-string without end-string.
/home/masahiro/ref/linux/Documentation/kbuild/makefiles.rst:1152: (WARNING/2) Inline emphasis start-string without end-string.
/home/masahiro/ref/linux/Documentation/kbuild/makefiles.rst:1154: (WARNING/2) Inline emphasis start-string without end-string.
These hunks were added by commit e846f0dc57f4 ("kbuild: add support
for ensuring headers are self-contained") and commit 1e21cbfada87
("kbuild: support header-test-pattern-y"), respectively. They were
written not for ReST but for the plain text, and merged via the
kbuild tree.
In the same development cycle, this document was converted to ReST
by commit cd238effefa2 ("docs: kbuild: convert docs to ReST and rename
to *.rst"), and merged via the doc sub-system.
Merging them together into Linus' tree resulted in the current situation.
To fix the syntax, surround the asterisks with back-quotes, and
use :: for the code sample.
Fixes: 39ceda5ce1b0 ("Merge tag 'kbuild-v5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild")
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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Currently, the timestamp of module linker scripts are not checked.
Add them to the dependency of modules so they are correctly rebuilt.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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These three variables are not intended to be tweaked by users.
Move them from kbuild.rst to makefiles.rst.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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'make clean' descends into ./Kbuild, but does not clean anything
since everything is added to no-clean-files.
There is no need to descend to ./Kbuild in the first place.
We can drop the no-clean-files assignment.
With this, there is no more user of no-clean-files. I will keep it
for a while to see whether a new user will appear.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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Pull more Kbuild updates from Masahiro Yamada:
- match the directory structure of the linux-libc-dev package to that
of Debian-based distributions
- fix incorrect include/config/auto.conf generation when Kconfig
creates it along with the .config file
- remove misleading $(AS) from documents
- clean up precious tag files by distclean instead of mrproper
- add a new coccinelle patch for devm_platform_ioremap_resource
migration
- refactor module-related scripts to read modules.order instead of
$(MODVERDIR)/*.mod files to get the list of created modules
- remove MODVERDIR
- update list of header compile-test
- add -fcf-protection=none flag to avoid conflict with the retpoline
flags when CONFIG_RETPOLINE=y
- misc cleanups
* tag 'kbuild-v5.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (25 commits)
kbuild: add -fcf-protection=none when using retpoline flags
kbuild: update compile-test header list for v5.3-rc1
kbuild: split out *.mod out of {single,multi}-used-m rules
kbuild: remove 'prepare1' target
kbuild: remove the first line of *.mod files
kbuild: create *.mod with full directory path and remove MODVERDIR
kbuild: export_report: read modules.order instead of .tmp_versions/*.mod
kbuild: modpost: read modules.order instead of $(MODVERDIR)/*.mod
kbuild: modsign: read modules.order instead of $(MODVERDIR)/*.mod
kbuild: modinst: read modules.order instead of $(MODVERDIR)/*.mod
scsi: remove pointless $(MODVERDIR)/$(obj)/53c700.ver
kbuild: remove duplication from modules.order in sub-directories
kbuild: get rid of kernel/ prefix from in-tree modules.{order,builtin}
kbuild: do not create empty modules.order in the prepare stage
coccinelle: api: add devm_platform_ioremap_resource script
kbuild: compile-test headers listed in header-test-m as well
kbuild: remove unused hostcc-option
kbuild: remove tag files by distclean instead of mrproper
kbuild: add --hash-style= and --build-id unconditionally
kbuild: get rid of misleading $(AS) from documents
...
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The assembler files in the kernel are *.S instead of *.s, so they must
be preprocessed. Since 'as' of GNU binutils is not able to preprocess,
we always use $(CC) as an assembler driver.
$(AS) is almost unused in Kbuild. As of v5.2, there is just one place
that directly invokes $(AS).
$ git grep -e '$(AS)' -e '${AS}' -e '$AS' -e '$(AS:' -e '${AS:' -- :^Documentation
drivers/net/wan/Makefile: AS68K = $(AS)
The documentation about *_AFLAGS* sounds like the flags were passed
to $(AS). This is somewhat misleading.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
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The tag ".. include" should be replaced by ".. literalinclude" at
issues.rst, otherwise it causes TeX to crash due to excessive usage
of stack with Sphinx 2.0.
While here, solve a few minor issues at the kbuild book output by
adding extra blank lines.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
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The contents of those directories were orphaned at the documentation
body.
While those directories could likely be moved to be inside some guide,
I'm opting to just adding their indexes to the main one, removing the
:orphan: and adding the SPDX header.
For the drivers, the rationale is that the documentation contains
a mix of Kernelspace, uAPI and admin-guide. So, better to keep them on
separate directories, as we've be doing with similar subsystem-specific
docs that were not split yet.
For the others, well... I'm too lazy to do the move. Also, it
seems to make sense to keep at least some of those at the main
dir (like kbuild, for example). In any case, a latter patch
could do the move.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
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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
...
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In old days, Kbuild always used an absolute path for $(srctree).
Since commit 890676c65d69 ("kbuild: Use relative path when building in
the source tree"), $(srctree) is '.' when O= was not passed from the
command line.
Yet, using absolute paths is useful in some cases even without O=, for
instance, to create a cscope file with absolute path tags.
'O=.' was known to work as a workaround to force Kbuild to use absolute
paths even when you are building in the source tree.
Since commit 25b146c5b8ce ("kbuild: allow Kbuild to start from any
directory"), Kbuild is too clever to be tricked. Even if you pass 'O=.'
Kbuild notices you are building in the source tree, then use '.' for
$(srctree).
So, 'make O=. cscope' is no help to create absolute path tags.
We cannot force one or the other according to commit e93bc1a0cab3
("Revert "kbuild: specify absolute paths for cscope""). Both of
relative path and absolute path have pros and cons.
This commit adds a new flag KBUILD_ABS_SRCTREE to allow users to
choose the absolute path for $(srctree).
'make KBUILD_ABS_SRCTREE=1 cscope' will work as a replacement of
'make O=. cscope'.
Reported-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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In my view, most of headers can be self-contained. So, it would be
tedious to add every header to header-test-y explicitly. We usually
end up with "all headers with some exceptions".
There are two types in exceptions:
[1] headers that are never compiled as standalone units
For examples, include/linux/compiler-gcc.h is not intended for
direct inclusion. We should always exclude such ones.
[2] headers that are conditionally compiled as standalone units
Some headers can be compiled only for particular architectures.
For example, include/linux/arm-cci.h can be compiled only for
arm/arm64 because it requires <asm/arm-cci.h> to exist.
Clang can compile include/soc/nps/mtm.h only for arc because
it contains an arch-specific register in inline assembler.
So, you can write Makefile like this:
header-test- += linux/compiler-gcc.h
header-test-$(CONFIG_ARM) += linux/arm-cci.h
header-test-$(CONFIG_ARM64) += linux/arm-cci.h
header-test-$(CONFIG_ARC) += soc/nps/mtm.h
The new syntax header-test-pattern-y will be useful to specify
"the rest".
The typical usage is like this:
header-test-pattern-y += */*.h
This will add all the headers in sub-directories to the test coverage,
excluding $(header-test-). In this regards, header-test-pattern-y
behaves like a weaker variant of header-test-y.
Caveat:
The patterns in header-test-pattern-y are prefixed with $(srctree)/$(src)/
but not $(objtree)/$(obj)/. Stale generated headers are often left over
when you traverse the git history without cleaning. Wildcard patterns for
$(objtree) may match to stale headers, which could fail to compile.
One pitfall is $(srctree)/$(src)/ and $(objtree)/$(obj)/ point to the
same directory for in-tree building. So, header-test-pattern-y should
be used with care since it can potentially match to stale headers.
Caveat2:
You could use wildcard for header-test-. For example,
header-test- += asm-generic/%
... will exclude headers in asm-generic directory. Unfortunately, the
wildcard character is '%' instead of '*' here because this is evaluated
by $(filter-out ...) whereas header-test-pattern-y is evaluated by
$(wildcard ...). This is a kludge, but seems useful in some places...
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Tested-by: Jani Nikula <jani.nikula@intel.com>
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header-test-y does not work with headers in sub-directories.
For example, you may want to write a Makefile, like this:
include/linux/Kbuild:
header-test-y += mtd/nand.h
This entry will create a wrapper include/linux/mtd/nand.hdrtest.c
with the following content:
#include "mtd/nand.h"
To make this work, we need to add $(srctree)/include/linux to the
header search path. It would be tedious to add ccflags-y.
Instead, we could change the *.hdrtest.c rule to wrap:
#include "nand.h"
This works for in-tree build since #include "..." searches in the
relative path from the header with this directive. For O=... build,
we need to add $(srctree)/include/linux/mtd to the header search path,
which will be even more tedious.
After all, I thought it would be handier to compile headers directly
without creating wrappers.
I added a new build rule to compile %.h into %.h.s
The target is %.h.s instead of %.h.o because it is slightly faster.
Also, as for GCC, an empty assembly is smaller than an empty object.
I wrote the build rule:
$(CC) $(c_flags) -S -o $@ -x c /dev/null -include $<
instead of:
$(CC) $(c_flags) -S -o $@ -x c $<
Both work fine with GCC, but the latter is bad for Clang.
This comes down to the difference in the -Wunused-function policy.
GCC does not warn about unused 'static inline' functions at all.
Clang does not warn about the ones in included headers, but does
about the ones in the source. So, we should handle headers as
headers, not as source files.
In fact, this has been hidden since commit abb2ea7dfd82 ("compiler,
clang: suppress warning for unused static inline functions"), but we
should not rely on that.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Tested-by: Jani Nikula <jani.nikula@intel.com>
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Sometimes it's useful to be able to explicitly ensure certain headers
remain self-contained, i.e. that they are compilable as standalone
units, by including and/or forward declaring everything they depend on.
Add special target header-test-y where individual Makefiles can add
headers to be tested if CONFIG_HEADER_TEST is enabled. This will
generate a dummy C file per header that gets built as part of extra-y.
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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headers_install_all does not make much sense any more because different
architectures export different set of uapi/linux/ headers. As you see
in include/uapi/linux/Kbuild, the installation of a.out.h, kvm.h, and
kvm_para.h is arch-dependent. So, headers_install_all repeats the
installation/removal of them.
If somebody really thinks it is useful to do headers_install for all
architectures, it would be possible by small shell-scripting, but
the top Makefile does not have to provide entry targets just for that
purpose.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
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The kbuild documentation clearly shows that the documents
there are written at different times: some use markdown,
some use their own peculiar logic to split sections.
Convert everything to ReST without affecting too much
the author's style and avoiding adding uneeded markups.
The conversion is actually:
- add blank lines and identation in order to identify paragraphs;
- fix tables markups;
- add some lists markups;
- mark literal blocks;
- adjust title markups.
At its new index.rst, let's add a :orphan: while this is not linked to
the main index.rst file, in order to avoid build warnings.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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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 <yamada.masahiro@socionext.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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Problem:
When a kernel module is compiled as a separate module, some important
information about the kernel module is available via .modinfo section of
the module. In contrast, when the kernel module is compiled into the
kernel, that information is not available.
Information about built-in modules is necessary in the following cases:
1. When it is necessary to find out what additional parameters can be
passed to the kernel at boot time.
2. When you need to know which module names and their aliases are in
the kernel. This is very useful for creating an initrd image.
Proposal:
The proposed patch does not remove .modinfo section with module
information from the vmlinux at the build time and saves it into a
separate file after kernel linking. So, the kernel does not increase in
size and no additional information remains in it. Information is stored
in the same format as in the separate modules (null-terminated string
array). Because the .modinfo section is already exported with a separate
modules, we are not creating a new API.
It can be easily read in the userspace:
$ tr '\0' '\n' < modules.builtin.modinfo
ext4.softdep=pre: crc32c
ext4.license=GPL
ext4.description=Fourth Extended Filesystem
ext4.author=Remy Card, Stephen Tweedie, Andrew Morton, Andreas Dilger, Theodore Ts'o and others
ext4.alias=fs-ext4
ext4.alias=ext3
ext4.alias=fs-ext3
ext4.alias=ext2
ext4.alias=fs-ext2
md_mod.alias=block-major-9-*
md_mod.alias=md
md_mod.description=MD RAID framework
md_mod.license=GPL
md_mod.parmtype=create_on_open:bool
md_mod.parmtype=start_dirty_degraded:int
...
Co-Developed-by: Gleb Fotengauer-Malinovskiy <glebfm@altlinux.org>
Signed-off-by: Gleb Fotengauer-Malinovskiy <glebfm@altlinux.org>
Signed-off-by: Alexey Gladkov <gladkov.alexey@gmail.com>
Acked-by: Jessica Yu <jeyu@kernel.org>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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Currently, every arch/*/include/uapi/asm/Kbuild explicitly includes
the common Kbuild.asm file. Factor out the duplicated include directives
to scripts/Makefile.asm-generic so that no architecture would opt out
of the mandatory-y mechanism.
um is not forced to include mandatory-y since it is a very exceptional
case which does not support UAPI.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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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 <major><minor>, while CONFIG_GCC_VERSION
<major><minor><patch>. I adjusted cc-ifversion for the difference of
the number of digits.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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Commit 06300b21f4c7 ("kbuild: support building individual files for
external modules") introduced the '/' target. It works only for
external modules to build all .o files, but skip the modpost stage.
However, 'make /' looks a bit weird to me. 'make ./' is more sensible
if you want to build all objects under the current directory, and it
works as expected.
Let's change '/' into a phony target that is an alias of './', but
I may feel like deprecating it in the future.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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The top Makefile does not need to export KBUILD_VMLINUX_INIT and
KBUILD_VMLINUX_MAIN separately.
Put every built-in.a into KBUILD_VMLINUX_OBJS. The order of
$(head-y), $(init-y), $(core-y), ... is still retained.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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The symbol table in the final archive is unneeded; the linker does not
require the symbol table after the --whole-archive option. Every object
file in the archive is included in the link anyway.
Pass thin archives from subdirectories directly to the linker, and
remove the final archiving step.
Fix up the document and comments as well.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Nicholas Piggin <npiggin@gmail.com>
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Some time ago, Sam pointed out a certain degree of overwrap between
generic-y and mandatory-y. (https://lkml.org/lkml/2017/7/10/121)
I tweaked the meaning of mandatory-y a little bit; now it defines the
minimum set of ASM headers that all architectures must have.
If arch does not have specific implementation of a mandatory header,
Kbuild will let it fallback to the asm-generic one by automatically
generating a wrapper. This will allow to drop lots of redundant
generic-y defines.
Previously, "mandatory" was used in the context of UAPI, but I guess
this can be extended to kernel space ASM headers.
Suggested-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
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SUBDIRS has been kept as a backward compatibility since
commit ("[PATCH] kbuild: external module support") in 2002.
We do not need multiple ways to do the same thing, so I will remove
SUBDIRS after the Linux 5.3 release. I cleaned up in-tree code, and
updated the document so that nobody would try to use it.
Meanwhile, display the following warning if SUBDIRS is used.
Makefile:189: ================= WARNING ================
Makefile:190: 'SUBDIRS' will be removed after Linux 5.3
Makefile:191: Please use 'M=' or 'KBUILD_EXTMOD' instead
Makefile:192: ==========================================
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Boris Brezillon <boris.brezillon@bootlin.com> # for scx200_docflash.c
Acked-by: Guenter Roeck <linux@roeck-us.net> # for scx200_wdt.c
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The last user of cc-fullversion was removed by commit f2910f0e6835
("powerpc: remove old GCC version checks").
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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This is a respin with a wider audience (all that get_maintainer returned)
and I know this spams a *lot* of people. Not sure what would be the correct
way, so my apologies for ruining your inbox.
The 00-INDEX files are supposed to give a summary of all files present
in a directory, but these files are horribly out of date and their
usefulness is brought into question. Often a simple "ls" would reveal
the same information as the filenames are generally quite descriptive as
a short introduction to what the file covers (it should not surprise
anyone what Documentation/sched/sched-design-CFS.txt covers)
A few years back it was mentioned that these files were no longer really
needed, and they have since then grown further out of date, so perhaps
it is time to just throw them out.
A short status yields the following _outdated_ 00-INDEX files, first
counter is files listed in 00-INDEX but missing in the directory, last
is files present but not listed in 00-INDEX.
List of outdated 00-INDEX:
Documentation: (4/10)
Documentation/sysctl: (0/1)
Documentation/timers: (1/0)
Documentation/blockdev: (3/1)
Documentation/w1/slaves: (0/1)
Documentation/locking: (0/1)
Documentation/devicetree: (0/5)
Documentation/power: (1/1)
Documentation/powerpc: (0/5)
Documentation/arm: (1/0)
Documentation/x86: (0/9)
Documentation/x86/x86_64: (1/1)
Documentation/scsi: (4/4)
Documentation/filesystems: (2/9)
Documentation/filesystems/nfs: (0/2)
Documentation/cgroup-v1: (0/2)
Documentation/kbuild: (0/4)
Documentation/spi: (1/0)
Documentation/virtual/kvm: (1/0)
Documentation/scheduler: (0/2)
Documentation/fb: (0/1)
Documentation/block: (0/1)
Documentation/networking: (6/37)
Documentation/vm: (1/3)
Then there are 364 subdirectories in Documentation/ with several files that
are missing 00-INDEX alltogether (and another 120 with a single file and no
00-INDEX).
I don't really have an opinion to whether or not we /should/ have 00-INDEX,
but the above 00-INDEX should either be removed or be kept up to date. If
we should keep the files, I can try to keep them updated, but I rather not
if we just want to delete them anyway.
As a starting point, remove all index-files and references to 00-INDEX and
see where the discussion is going.
Signed-off-by: Henrik Austad <henrik@austad.us>
Acked-by: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Just-do-it-by: Steven Rostedt <rostedt@goodmis.org>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Paul Moore <paul@paul-moore.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Mark Brown <broonie@kernel.org>
Acked-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: [Almost everybody else]
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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Fixes: 8377bd2b9ee1 ("kbuild: Rename HOST_LOADLIBES to KBUILD_HOSTLDLIBS")
Signed-off-by: Michal Suchanek <msuchanek@suse.de>
Acked-by: Laura Abbott <labbott@redhat.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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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 <yamada.masahiro@socionext.com>
Tested-by: Dirk Gouders <dirk@gouders.net>
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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
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Fix a couple of punctuation "typos" in the description of the
"choice" keyword.
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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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 <dirk@gouders.net>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
|
Masahiro Yamada
Masahiro Yamada
Linus Torvalds
Dmitry Goldin
Alex Gaynor
Ben Hutchings
Matthias Maennich
Mauro Carvalho Chehab
Jani Nikula
Nick Desaulniers
Alexey Gladkov
Henrik Austad
Michal Suchanek
Randy Dunlap
Dirk Gouders