linux-toradex.git/scripts/Kbuild.include, branch toradex_5.3.y

kbuild: remove unused objectify macro

2019-07-27T03:18:19+00:00

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

2019-07-17T13:37:51+00:00

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

2019-07-12T23:03:16+00:00

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

2019-07-11T14:34:52+00:00

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

2019-07-01T01:03:40+00:00

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

kbuild: save $(strip ...) for calling any-prepreq

2019-07-01T01:03:15+00:00

The string returned by $(filter-out ...) does not contain any leading
or trailing spaces.

So, only the space that matters is the one between

  $(filter-out $(PHONY),$?)

and

  $(filter-out $(PHONY) $(wildcard $^),$^)

By removing it from the code, we can save $(strip ...) evaluation.
This refactoring is possible because $(any-prereq) is only passed to
the first argument of $(if ...), so we are only interested in whether
or not it is empty.

This is also the prerequisite for the next commit.

Signed-off-by: Masahiro Yamada

kbuild: rename arg-check to cmd-check

2019-07-01T01:03:07+00:00

I prefer 'cmd-check' for consistency.

We have 'echo-cmd', 'cmd', 'cmd_and_fixdep', etc. in this file.

Signed-off-by: Masahiro Yamada

kbuild: move hdr-inst shorthand to top Makefile

2019-06-15T10:57:02+00:00

Now that hdr-inst is used only in the top Makefile, move it there
from scripts/Kbuild.include.

Signed-off-by: Masahiro Yamada

docs: kbuild: convert docs to ReST and rename to *.rst

2019-06-14T20:21:21+00:00

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 
Signed-off-by: Jonathan Corbet

kbuild: use more portable 'command -v' for cc-cross-prefix

2019-06-07T15:38:47+00:00

To print the pathname that will be used by shell in the current
environment, 'command -v' is a standardized way. [1]

'which' is also often used in scripts, but it is less portable.

When I worked on commit bd55f96fa9fc ("kbuild: refactor cc-cross-prefix
implementation"), I was eager to use 'command -v' but it did not work.
(The reason is explained below.)

I kept 'which' as before but got rid of '> /dev/null 2>&1' as I
thought it was no longer needed. Sorry, I was wrong.

It works well on my Ubuntu machine, but Alexey Brodkin reports noisy
warnings on CentOS7 when 'which' fails to find the given command in
the PATH environment.

  $ which foo
  which: no foo in (/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin)

Given that behavior of 'which' depends on system (and it may not be
installed by default), I want to try 'command -v' once again.

The specification [1] clearly describes the behavior of 'command -v'
when the given command is not found:

  Otherwise, no output shall be written and the exit status shall reflect
  that the name was not found.

However, we need a little magic to use 'command -v' from Make.

$(shell ...) passes the argument to a subshell for execution, and
returns the standard output of the command.

Here is a trick. GNU Make may optimize this by executing the command
directly instead of forking a subshell, if no shell special characters
are found in the command and omitting the subshell will not change the
behavior.

In this case, no shell special character is used. So, Make will try
to run it directly. However, 'command' is a shell-builtin command,
then Make would fail to find it in the PATH environment:

  $ make ARCH=m68k defconfig
  make: command: Command not found
  make: command: Command not found
  make: command: Command not found

In fact, Make has a table of shell-builtin commands because it must
ask the shell to execute them.

Until recently, 'command' was missing in the table.

This issue was fixed by the following commit:

| commit 1af314465e5dfe3e8baa839a32a72e83c04f26ef
| Author: Paul Smith 
| Date:   Sun Nov 12 18:10:28 2017 -0500
|
|     * job.c: Add "command" as a known shell built-in.
|
|     This is not a POSIX shell built-in but it's common in UNIX shells.
|     Reported by Nick Bowler .

Because the latest release is GNU Make 4.2.1 in 2016, this commit is
not included in any released versions. (But some distributions may
have back-ported it.)

We need to trick Make to spawn a subshell. There are various ways to
do so:

 1) Use a shell special character '~' as dummy

    $(shell : ~; command -v $(c)gcc)

 2) Use a variable reference that always expands to the empty string
    (suggested by David Laight)

    $(shell command$${x:+} -v $(c)gcc)

 3) Use redirect

    $(shell command -v $(c)gcc 2>/dev/null)

I chose 3) to not confuse people. The stderr would not be polluted
anyway, but it will provide extra safety, and is easy to understand.

Tested on Make 3.81, 3.82, 4.0, 4.1, 4.2, 4.2.1

[1] http://pubs.opengroup.org/onlinepubs/9699919799/utilities/command.html

Fixes: bd55f96fa9fc ("kbuild: refactor cc-cross-prefix implementation")
Cc: linux-stable  # 5.1
Reported-by: Alexey Brodkin 
Signed-off-by: Masahiro Yamada 
Tested-by: Alexey Brodkin