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  1. Jul 25, 2018
    • Masahiro Yamada's avatar
      kbuild: add .DELETE_ON_ERROR special target · 9c2af1c7
      Masahiro Yamada authored 
      

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: default avatarMasahiro Yamada <yamada.masahiro@socionext.com>
      9c2af1c7
    • Masahiro Yamada's avatar
      kbuild: use 'include' directive to load auto.conf from top Makefile · 0a16d2e8
      Masahiro Yamada authored 
      

When you build targets that require the kernel configuration, dot-config
is set to 1, then the top-level Makefile includes auto.conf.  However,
Make considers its inclusion is optional because the '-include' directive
is used here.

If a necessary configuration file is missing for the external module
building, the following error message is displayed:

  ERROR: Kernel configuration is invalid.
         include/generated/autoconf.h or include/config/auto.conf are missing.
         Run 'make oldconfig && make prepare' on kernel src to fix it.

However, Make still continues building; /bin/false let the creation of
'include/config/auto.config' fail, but Make can ignore the error since
it is included by the '-include' directive.

I guess the reason of using '-include' directive was to suppress
the warning when you build the kernel from a pristine source tree:

  Makefile:605: include/config/auto.conf: No such file or directory

The previous commit made sure include/config/auto.conf exists after
the 'make *config' stage.  Now, we can use the 'include' directive
without showing the warning.

Signed-off-by: default avatarMasahiro Yamada <yamada.masahiro@socionext.com>
      0a16d2e8
    • Masahiro Yamada's avatar
      kconfig: allow all config targets to write auto.conf if missing · 00c864f8
      Masahiro Yamada authored 
      

Currently, only syncconfig creates or updates include/config/auto.conf
and some other files.  Other config targets create or update only the
.config file.

When you configure and build the kernel from a pristine source tree,
any config target is followed by syncconfig in the build stage since
include/config/auto.conf is missing.

We are moving compiler tests from Makefile to Kconfig.  It means that
parsing Kconfig files will be more costly since Kconfig invokes the
compiler commands internally.  Thus, we want to avoid invoking Kconfig
twice (one for *config to create the .config, and one for syncconfig
to synchronize the auto.conf).  If auto.conf does not exist, we can
generate all configuration files in the first configuration stage,
which will save the syncconfig in the build stage.

Please note this should be done only when auto.conf is missing.  If
*config blindly did this, time stamp files under include/config/ would
be unnecessarily touched, triggering unneeded rebuild of objects.

I assume a scenario like this:

 1. You have a source tree that has already been built
    with CONFIG_FOO disabled

 2. Run "make menuconfig" to enable CONFIG_FOO

 3. CONFIG_FOO turns out to be unnecessary.
    Run "make menuconfig" again to disable CONFIG_FOO

 4. Run "make"

In this case, include/config/foo.h should not be touched since there
is no change in CONFIG_FOO.  The sync process should be delayed until
the user really attempts to build the kernel.

This commit has another motivation; I want to suppress the 'No such
file or directory' warning from the 'include' directive.

The top-level Makefile includes auto.conf with '-include' directive,
like this:

  ifeq ($(dot-config),1)
  -include include/config/auto.conf
  endif

This looks strange because auto.conf is mandatory when dot-config is 1.
I guess only the reason of using '-include' is to suppress the warning
'include/config/auto.conf: No such file or directory' when building
from a clean tree.  However, this has a side-effect; Make considers
the files included by '-include' are optional.  Hence, Make continues
to build even if it fails to generate include/config/auto.conf.  I will
change this in the next commit, but the warning message is annoying.
(At least, kbuild test robot reports it as a regression.)

With this commit, Kconfig will generate all configuration files together
with the .config and I guess it is a solution good enough to suppress
the warning.

Note:
GNU Make 4.2 or later does not display the warning from the 'include'
directive if include files are successfully generated.  See GNU Make
commit 87a5f98d248f ("[SV 102] Don't show unnecessary include file
errors.")  However, older GNU Make versions are still widely used.

Signed-off-by: default avatarMasahiro Yamada <yamada.masahiro@socionext.com>
      00c864f8
    • Masahiro Yamada's avatar
      kconfig: make syncconfig update .config regardless of sym_change_count · 16952b77
      Masahiro Yamada authored 
      

syncconfig updates the .config only when sym_change_count > 0, i.e.
any change in config symbols has been detected.

Not only symbols but also comments are contained in the .config file.
If only comments are updated, they are not fed back to the .config,
then the stale comments are left-over.  Of course, this is just a
matter of comments, but why not fix it.

I see some scenarios where this happens.

Scenario A:

 1. You have a source tree that has already been configured.

 2. Linus increments the version number in the top-level Makefile
    (i.e. he commits a new release)

 3. You pull it, and run 'make'

 4. syncconfig is invoked because the environment variable,
    KERNELVERSION is updated, but the .config is not updated since
    no config symbol is changed.

 5. The .config file contains a kernel version in the top line:

    # Automatically generated file; DO NOT EDIT.
    # Linux/arm64 4.18.0-rc2 Kernel Configuration

    ... which points to a previous version.

Scenario B:

 1. You have a source tree that has already been configured.

 2. You upgrade the compiler, but it still has the same version number.
    This may happen if you regularly build the latest compiler from
    the source code.

 3. You run 'make'

 4. syncconfig is invoked because the environment variable,
    CC_VERSION_TEXT is updated, but the .config is not updated since
    no config symbol is changed.

 5. The .config file contains the version string of the compiler:

    #
    # Compiler: aarch64-linux-gcc (GCC) 9.0.0 20180628 (experimental)
    #

    ... which carries the information of the old compiler.

If KCONFIG_NOSILENTUPDATE is set, syncconfig is not allowed to update
the .config file.  Otherwise, it is fine to update it regardless of
sym_change_count.

Signed-off-by: default avatarMasahiro Yamada <yamada.masahiro@socionext.com>
      16952b77
    • Masahiro Yamada's avatar
      kconfig: create directories needed for syncconfig by itself · 79123b13
      Masahiro Yamada authored 
      

'make syncconfig' creates some files such as include/config/auto.conf,
include/generate/autoconf.h, etc. but the necessary directory creation
relies on scripts/kconfig/Makefile.

To make Kconfig self-contained, create directories as needed in
conf_write_autoconf().

This change allows scripts/kconfig/Makefile cleanups; syncconfig can
be merged into simple-targets.

Signed-off-by: default avatarMasahiro Yamada <yamada.masahiro@socionext.com>
      79123b13
    • Masahiro Yamada's avatar
      kconfig: remove unneeded directory generation from local*config · adc18acf
      Masahiro Yamada authored 
      Commit 17263baf ("kconfig: Create include/generated for
localmodconfig") added the 'mkdir' line because local{yes,mod}config
ran streamline_config.pl followed by silentoldconfig at that time.

Since commit 81d2bc22

 ("kconfig: invoke oldconfig instead of
silentoldconfig from local*config"), no sub-directory is required.

Signed-off-by: default avatarMasahiro Yamada <yamada.masahiro@socionext.com>
      adc18acf
    • Masahiro Yamada's avatar
      kconfig: split out useful helpers in confdata.c · 0608182a
      Masahiro Yamada authored 
      

Split out helpers:
 is_present() - check if the given path exists
 is_dir() - check if the given path exists and it is a directory
 make_parent_dir() - create the parent directories of the given path

These helpers will be reused in later commits.

Signed-off-by: default avatarMasahiro Yamada <yamada.masahiro@socionext.com>
      0608182a
    • Masahiro Yamada's avatar
      kconfig: rename file_write_dep and move it to confdata.c · a2ff4040
      Masahiro Yamada authored 
      

file_write_dep() is called only from conf_write_autoconf().
Move it from util.c to confdata.c to make it static.
Also, rename it to conf_write_dep() since it should belong to
the group of conf_write* functions.

Signed-off-by: default avatarMasahiro Yamada <yamada.masahiro@socionext.com>
      a2ff4040
    • Randy Dunlap's avatar
      kconfig: fix typos in description of "choice" in kconfig-language.txt · 08b220b3
      Randy Dunlap authored 
      

Fix a couple of punctuation "typos" in the description of the
"choice" keyword.

Signed-off-by: default avatarRandy Dunlap <rdunlap@infradead.org>
Signed-off-by: default avatarMasahiro Yamada <yamada.masahiro@socionext.com>
      08b220b3
    • Masahiro Yamada's avatar
      kconfig: handle format string before calling conf_message_callback() · 5accd7f3
      Masahiro Yamada authored 
      

As you see in mconf.c and nconf.c, conf_message_callback() hooks are
likely to end up with the boilerplate of vsnprintf().  Process the
string format before calling conf_message_callback() so that it
receives a simple string.

Signed-off-by: default avatarMasahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: default avatarDirk Gouders <dirk@gouders.net>
      5accd7f3
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