Commit Graph

126 Commits

Author SHA1 Message Date
Linus Torvalds
9c2dd8405c Merge tag 'devicetree-for-4.17' of git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux
Pull DeviceTree updates from Rob Herring:

 - Sync dtc to upstream version v1.4.6-9-gaadd0b65c987. This adds a
   bunch more warnings (hidden behind W=1).

 - Build dtc lexer and parser files instead of using shipped versions.

 - Rework overlay apply API to take an FDT as input and apply overlays
   in a single step.

 - Add a phandle lookup cache. This improves boot time by hundreds of
   msec on systems with large DT.

 - Add trivial mcp4017/18/19 potentiometers bindings.

 - Remove VLA stack usage in DT code.

* tag 'devicetree-for-4.17' of git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux: (26 commits)
  of: unittest: fix an error code in of_unittest_apply_overlay()
  of: unittest: move misplaced function declaration
  of: unittest: Remove VLA stack usage
  of: overlay: Fix forgotten reference to of_overlay_apply()
  of: Documentation: Fix forgotten reference to of_overlay_apply()
  of: unittest: local return value variable related cleanups
  of: unittest: remove unneeded local return value variables
  dt-bindings: trivial: add various mcp4017/18/19 potentiometers
  of: unittest: fix an error test in of_unittest_overlay_8()
  of: cache phandle nodes to reduce cost of of_find_node_by_phandle()
  dt-bindings: rockchip-dw-mshc: use consistent clock names
  MAINTAINERS: Add linux/of_*.h headers to appropriate subsystems
  scripts: turn off some new dtc warnings by default
  scripts/dtc: Update to upstream version v1.4.6-9-gaadd0b65c987
  scripts/dtc: generate lexer and parser during build instead of shipping
  powerpc: boot: add strrchr function
  of: overlay: do not include path in full_name of added nodes
  of: unittest: clean up changeset test
  arm64/efi: Make strrchr() available to the EFI namespace
  ARM: boot: add strrchr function
  ...
2018-04-05 21:03:42 -07:00
Masahiro Yamada
a95b37e20d kbuild: get <linux/compiler_types.h> out of <linux/kconfig.h>
Since commit 28128c61e0 ("kconfig.h: Include compiler types to avoid
missed struct attributes"), <linux/kconfig.h> pulls in kernel-space
headers to unrelated places.

Commit 0f9da844d8 ("MIPS: boot: Define __ASSEMBLY__ for its.S build")
suppress the build error by defining __ASSEMBLY__, but ITS (i.e. DTS)
is not assembly, and should not include <linux/compiler_types.h> in the
first place.

Looking at arch/s390/tools/Makefile, host programs gen_facilities and
gen_opcode_table now pull in <linux/compiler_types.h> as well.

The motivation for that commit was to define necessary attributes
before any struct is defined.  Obviously, this happens only in C.

It is enough to include <linux/compiler_types.h> only when compiling
C files, and only when compiling kernel space.  Move the include to
c_flags.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2018-03-31 12:22:38 +09:00
Masahiro Yamada
f98fe47ce5 kbuild: link $(real-obj-y) instead of $(obj-y) into built-in.a
In Kbuild, Makefiles can add the same object to obj-y multiple
times.  So,

   obj-y += foo.o
   obj-y += foo.o

is fine.

However, this is not true when the same object is added multiple
times via composite objects.  For example,

   obj-y    += foo.o bar.o
   foo-objs := foo-bar-common.o foo-only.o
   bar-objs := foo-bar-common.o bar-only.o

causes build error because two instances of foo-bar-common.o are
linked into the vmlinux.

Makefiles tend to invent ugly work-around, for example
  - lib/zstd/Makefile
  - drivers/net/ethernet/cavium/liquidio/Makefile

The technique used in Kbuild to avoid the multiple definition error
is to use $(filter $(obj-y), $^).  Here, $^ lists the names of all
the prerequisites with duplicated names removed.

By replacing it with $(filter $(real-obj-y), $^) we can do likewise
for composite objects.  For built-in objects, we do not need to keep
the composite object structure.  We can simply expand them, and link
$(real-obj-y) to built-in.a.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2018-03-26 02:01:27 +09:00
Masahiro Yamada
f5f336812c kbuild: rename real-objs-y/m to real-obj-y/m
When I was refactoring Makefiles, I stupidly mistook 'real-obj-y' for
'real-objs-y' over and over again.  Finally, I decide to rename it to
'real-obj-y'.  This is consistent with 'obj-y', 'subdir-obj-y'.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2018-03-26 02:01:26 +09:00
Masahiro Yamada
c0152e9a6b kbuild: move modname and modname-multi close to modname_flags
Just a cosmetic change to put related code close together.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Cao jin <caoj.fnst@cn.fujitsu.com>
2018-03-26 02:01:26 +09:00
Masahiro Yamada
fe852ac200 kbuild: simplify modname calculation
modname can be calculated much more simply.  If modname-multi is
empty, it is a single-used object.  So, modname = $(basetarget).
Otherwise, modname = $(modname-multi).

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Cao jin <caoj.fnst@cn.fujitsu.com>
2018-03-26 02:01:25 +09:00
Cao jin
c96a294eb6 kbuild: fix modname for composite modules
Commit cf4f21938e ("kbuild: Allow to specify composite modules
with modname-m") added modname-m support, but missed to update the
corresponding multi-objs-m & modname-multi definition.

Signed-off-by: Cao jin <caoj.fnst@cn.fujitsu.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2018-03-26 02:01:25 +09:00
Masahiro Yamada
aeacb019b6 kbuild: define KBUILD_MODNAME even if multiple modules share objects
Currently, KBUILD_MODNAME is defined only when $(modname) contains
just one word.  If an object is shared among multiple modules,
undefined KBUILD_MODNAME could cause a build error.  For example,
if CONFIG_DYNAMIC_DEBUG is enabled, any call of printk() populates
.modname, then fails to build due to undefined KBUILD_MODNAME.

Take the following code as an example:

  obj-m += foo.o
  obj-m += bar.o
  foo-objs := foo-bar-common.o foo-only.o
  bar-objs := foo-bar-common.o bar-only.o

In this case, there is room for argument what to define for
KBUILD_MODNAME when foo-bar-common.o is being compiled.
"foo", "bar", or what else?

One idea is to define colon-separated modules that share the object,
in this case, "bar:foo" (modules are sorted alphabetically by
$(sort ...)).

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Cao jin <caoj.fnst@cn.fujitsu.com>
2018-03-26 02:01:25 +09:00
Masahiro Yamada
8cd0e46d3f kbuild: remove unnecessary $(subst $(obj)/, , ...) in modname-multi
In the context ...

    $(obj)/%.s: $(src)/%.c FORCE
            $(call if_changed_dep,cc_s_c)

    $(obj)/%.i: $(src)/%.c FORCE
            $(call if_changed_dep,cpp_i_c)

    $(obj)/%.o: $(src)/%.c $(recordmcount_source) $(objtool_dep) FORCE
            $(call cmd,force_checksrc)
            $(call if_changed_rule,cc_o_c)

    $(obj)/%.lst: $(src)/%.c FORCE
            $(call if_changed_dep,cc_lst_c)

'$*' returns the stem of the target (the part of '%'), so $(obj)/ has
already been ripped off.

$(subst $(obj)/,,$*.o) is the same as $*.o

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Cao jin <caoj.fnst@cn.fujitsu.com>
2018-03-26 02:01:24 +09:00
Michael Forney
a670b0b4ae kbuild: Use ls(1) instead of stat(1) to obtain file size
stat(1) is not standardized and different implementations have their own
(conflicting) flags for querying the size of a file.

ls(1) provides the same information (value of st.st_size) in the 5th
column, except when the file is a character or block device. This output
is standardized[0]. The -n option turns on -l, which writes lines
formatted like

  "%s %u %s %s %u %s %s\n", <file mode>, <number of links>,
      <owner name>, <group name>, <size>, <date and time>,
      <pathname>

but instead of writing the <owner name> and <group name>, it writes the
numeric owner and group IDs (this avoids /etc/passwd and /etc/group
lookups as well as potential field splitting issues).

The <size> field is specified as "the value that would be returned for
the file in the st_size field of struct stat".

To avoid duplicating logic in several locations in the tree, create
scripts/file-size.sh and update callers to use that instead of stat(1).

[0] http://pubs.opengroup.org/onlinepubs/9699919799/utilities/ls.html#tag_20_73_10

Signed-off-by: Michael Forney <forney@google.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2018-03-26 02:01:24 +09:00
Nicholas Piggin
f49821ee32 kbuild: rename built-in.o to built-in.a
Incremental linking is gone, so rename built-in.o to built-in.a, which
is the usual extension for archive files.

This patch does two things, first is a simple search/replace:

git grep -l 'built-in\.o' | xargs sed -i 's/built-in\.o/built-in\.a/g'

The second is to invert nesting of nested text manipulations to avoid
filtering built-in.a out from libs-y2:

-libs-y2 := $(filter-out %.a, $(patsubst %/, %/built-in.a, $(libs-y)))
+libs-y2 := $(patsubst %/, %/built-in.a, $(filter-out %.a, $(libs-y)))

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2018-03-26 02:01:19 +09:00
James Hogan
55fe6da9ef kbuild: Handle builtin dtb file names containing hyphens
cmd_dt_S_dtb constructs the assembly source to incorporate a devicetree
FDT (that is, the .dtb file) as binary data in the kernel image. This
assembly source contains labels before and after the binary data. The
label names incorporate the file name of the corresponding .dtb file.
Hyphens are not legal characters in labels, so .dtb files built into the
kernel with hyphens in the file name result in errors like the
following:

bcm3368-netgear-cvg834g.dtb.S: Assembler messages:
bcm3368-netgear-cvg834g.dtb.S:5: Error: : no such section
bcm3368-netgear-cvg834g.dtb.S:5: Error: junk at end of line, first unrecognized character is `-'
bcm3368-netgear-cvg834g.dtb.S:6: Error: unrecognized opcode `__dtb_bcm3368-netgear-cvg834g_begin:'
bcm3368-netgear-cvg834g.dtb.S:8: Error: unrecognized opcode `__dtb_bcm3368-netgear-cvg834g_end:'
bcm3368-netgear-cvg834g.dtb.S:9: Error: : no such section
bcm3368-netgear-cvg834g.dtb.S:9: Error: junk at end of line, first unrecognized character is `-'

Fix this by updating cmd_dt_S_dtb to transform all hyphens from the file
name to underscores when constructing the labels.

As of v4.16-rc2, 1139 .dts files across ARM64, ARM, MIPS and PowerPC
contain hyphens in their names, but the issue only currently manifests
on Broadcom MIPS platforms, as that is the only place where such files
are built into the kernel. For example when CONFIG_DT_NETGEAR_CVG834G=y,
or on BMIPS kernels when the dtbs target is used (in the latter case it
admittedly shouldn't really build all the dtb.o files, but thats a
separate issue).

Fixes: 695835511f ("MIPS: BMIPS: rename bcm96358nb4ser to bcm6358-neufbox4-sercom")
Signed-off-by: James Hogan <jhogan@kernel.org>
Reviewed-by: Frank Rowand <frowand.list@gmail.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Michal Marek <michal.lkml@markovi.net>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Kevin Cernekee <cernekee@gmail.com>
Cc: <stable@vger.kernel.org> # 4.9+
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2018-03-09 01:14:38 +09:00
Rob Herring
4fd98e374f scripts: turn off some new dtc warnings by default
The latest dtc update adds some new noisy warnings, so turn them off by
default. Disable 'avoid_unnecessary_addr_size' and 'alias_paths'. They
can be re-enabled by building with 'W=1'.

Signed-off-by: Rob Herring <robh@kernel.org>
2018-03-05 20:58:18 -06:00
Rob Herring
f26e93812a scripts: re-enable some now fixed dtc warnings
We can re-enable some dtc warnings that have been completely or mostly
fixed. There are a few remaining ones in arm64 dts files which crept in
recently.

Signed-off-by: Rob Herring <robh@kernel.org>
2018-03-01 12:02:48 -06:00
Rob Herring
b8fc5b2157 kbuild: add dtc as dependency on .dtb files
If dtc is rebuilt, we should rebuild .dtb files with the new dtc.

Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Rob Herring <robh@kernel.org>
2018-03-01 12:02:24 -06:00
Rob Herring
e71de5ee08 kbuild: remove remaining use of undefined YACC_PREFIX
Commit eea199b445 ("kbuild: remove unnecessary LEX_PREFIX and
YACC_PREFIX") removed YACC_PREFIX definition, but left one use of it. There
was not any build error since there is no user of "cmd_bison_h" currently.
Remove the last remaining occurrence of YACC_PREFIX.

Fixes: eea199b445 ("kbuild: remove unnecessary LEX_PREFIX and YACC_PREFIX")
Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Rob Herring <robh@kernel.org>
2018-03-01 12:01:54 -06:00
Andrey Konovalov
0e410e158e kasan: don't emit builtin calls when sanitization is off
With KASAN enabled the kernel has two different memset() functions, one
with KASAN checks (memset) and one without (__memset).  KASAN uses some
macro tricks to use the proper version where required.  For example
memset() calls in mm/slub.c are without KASAN checks, since they operate
on poisoned slab object metadata.

The issue is that clang emits memset() calls even when there is no
memset() in the source code.  They get linked with improper memset()
implementation and the kernel fails to boot due to a huge amount of KASAN
reports during early boot stages.

The solution is to add -fno-builtin flag for files with KASAN_SANITIZE :=
n marker.

Link: http://lkml.kernel.org/r/8ffecfffe04088c52c42b92739c2bd8a0bcb3f5e.1516384594.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Michal Marek <michal.lkml@markovi.net>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-06 18:32:42 -08:00
Linus Torvalds
562f36ed28 Merge tag 'kconfig-v4.16' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kconfig updates from Masahiro Yamada:
 "A pretty big batch of Kconfig updates.

  I have to mention the lexer and parser of Kconfig are now built from
  real .l and .y sources. So, flex and bison are the requirement for
  building the kernel. Both of them (unlike gperf) have been stable for
  a long time. This change has been tested several weeks in linux-next,
  and I did not receive any problem report about this.

  Summary:

   - add checks for mistakes, like the choice default is not in choice,
     help is doubled

   - document data structure and complex code

   - fix various memory leaks

   - change Makefile to build lexer and parser instead of using
     pre-generated C files

   - drop 'boolean' keyword, which is equivalent to 'bool'

   - use default 'yy' prefix and remove unneeded Make variables

   - fix gettext() check for xconfig

   - announce that oldnoconfig will be finally removed

   - make 'Selected by:' and 'Implied by' readable in help and search
     result

   - hide silentoldconfig from 'make help' to stop confusing people

   - fix misc things and cleanups"

* tag 'kconfig-v4.16' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (37 commits)
  kconfig: Remove silentoldconfig from help and docs; fix kconfig/conf's help
  kconfig: make "Selected by:" and "Implied by:" readable
  kconfig: announce removal of oldnoconfig if used
  kconfig: fix make xconfig when gettext is missing
  kconfig: Clarify menu and 'if' dependency propagation
  kconfig: Document 'if' flattening logic
  kconfig: Clarify choice dependency propagation
  kconfig: Document SYMBOL_OPTIONAL logic
  kbuild: remove unnecessary LEX_PREFIX and YACC_PREFIX
  kconfig: use default 'yy' prefix for lexer and parser
  kconfig: make conf_unsaved a local variable of conf_read()
  kconfig: make xfgets() really static
  kconfig: make input_mode static
  kconfig: Warn if there is more than one help text
  kconfig: drop 'boolean' keyword
  kconfig: use bool instead of boolean for type definition attributes, again
  kconfig: Remove menu_end_entry()
  kconfig: Document important expression functions
  kconfig: Document automatic submenu creation code
  kconfig: Fix choice symbol expression leak
  ...
2018-02-01 11:45:49 -08:00
Masahiro Yamada
f759625ad2 kbuild: fix W= option checks for extra DTC warnings
Kbuild supports 3 levels of extra warnings, and multiple levels can
be combined, like W=12, W=123.  It was added by commit a6de553da0
("kbuild: Allow to combine multiple W= levels").

From the log of commit 8654cb8d03 ("dtc: update warning settings
for new bus and node/property name checks"), I assume:

 - unit_address_vs_reg, simple_bus_reg, etc. belong to level 1
 - node_name_chars_strict, property_name_chars_strict belong to level 2

However, the level 1 warnings are displayed by any argument to W=.
On the other hand, the level 2 warnings are displayed by W=2, but
not by W=12, or W=123.

Use $(findstring ...) like scripts/Makefile.extrawarn.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
2018-01-25 22:17:25 +09:00
Masahiro Yamada
eea199b445 kbuild: remove unnecessary LEX_PREFIX and YACC_PREFIX
Kconfig was the only user of these.  With Kconfig converted to use
the default 'yy' prefix, we do not need them any more.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Ulf Magnusson <ulfalizer@gmail.com>
2018-01-22 00:49:31 +09:00
Masahiro Yamada
033dba2ec0 kbuild: prepare to remove C files pre-generated by flex and bison
In Linux build system convention, pre-generated files are version-
controlled with a "_shipped" suffix.  During the kernel building,
they are simply shipped (copied) removing the suffix.

This approach can reduce external tool dependency for the kernel build,
but it is tedious to manually regenerate such artifacts from developers'
point of view.  (We need to do "make REGENERATE_PARSERS=1" every time
we touch real source files such as *.l, *.y)

Some months ago, I sent out RFC patches to run flex, bison, and gperf
during the build.

In the review and test, Linus noticed gperf-3.1 had changed the lookup
function prototype.  Then, the use of gperf in kernel was entirely
removed by commit bb3290d916 ("Remove gperf usage from toolchain").

This time, I tested several versions of flex and bison, and I was not
hit by any compatibility issue except a flaw in flex-2.6.3; if you
generate lexer for dtc and genksyms with flex-2.6.3, you will see
"yywrap redefined" warning.  This was not intentional, but a bug,
fixed by flex-2.6.4.  Otherwise, both flex and bison look fairly
stable for a long time.

This commit prepares some build rules to remove the _shipped files.
Also, document minimal requirement for flex and bison.

Rationale for the minimal version:
The -Wmissing-prototypes option of GCC warns "no previous prototype"
for lexers generated by flex-2.5.34 or older, so I chose 2.5.35 as the
required version for flex.  Flex-2.5.35 was released in 2008.  Bison
looks more stable.  I did not see any problem with bison-2.0, released
in 2004.  I did not test bison-1.x, but bison-2.0 should be old enough.

Tested flex versions:
  2.5.35
  2.5.36
  2.5.37
  2.5.39
  2.6.0
  2.6.1
  2.6.2
  2.6.3   (*)
  2.6.4

 (*) flex-2.6.3 causes "yywrap redefined" warning

Tested bison versions:
  2.0
  2.1
  2.2
  2.3
  2.4
  2.4.1
  2.5.1
  2.6
  2.6.1
  2.6.2
  2.6.3
  2.6.4
  2.6.5
  2.7
  2.7.1
  3.0
  3.0.1
  3.0.2
  3.0.3
  3.0.4

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2017-12-16 11:12:53 +09:00
Masahiro Yamada
73a4f6dbe7 kbuild: add LEX and YACC variables
Allow users to use their favorite lexer / parser generators.
This is useful for me to test various flex and bison versions.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2017-12-16 11:12:53 +09:00
Masahiro Yamada
10aaa3b7e9 kbuild: drop $(extra-y) from real-objs-y
$(real-objs-y) in only used in scripts/Makefile.build to form
"targets", but $(extra-y) is added to "targets" in another line.
We do not need to add $(extra-y) twice.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2017-11-23 23:29:26 +09:00
Linus Torvalds
09bd7c75e5 Merge tag 'kbuild-v4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kbuild updates from Masahiro Yamada:
 "One of the most remarkable improvements in this cycle is, Kbuild is
  now able to cache the result of shell commands. Some variables are
  expensive to compute, for example, $(call cc-option,...) invokes the
  compiler. It is not efficient to redo this computation every time,
  even when we are not actually building anything. Kbuild creates a
  hidden file ".cache.mk" that contains invoked shell commands and their
  results. The speed-up should be noticeable.

  Summary:

   - Fix arch build issues (hexagon, sh)

   - Clean up various Makefiles and scripts

   - Fix wrong usage of {CFLAGS,LDFLAGS}_MODULE in arch Makefiles

   - Cache variables that are expensive to compute

   - Improve cc-ldopton and ld-option for Clang

   - Optimize output directory creation"

* tag 'kbuild-v4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (30 commits)
  kbuild: move coccicheck help from scripts/Makefile.help to top Makefile
  sh: decompressor: add shipped files to .gitignore
  frv: .gitignore: ignore vmlinux.lds
  selinux: remove unnecessary assignment to subdir-
  kbuild: specify FORCE in Makefile.headersinst as .PHONY target
  kbuild: remove redundant mkdir from ./Kbuild
  kbuild: optimize object directory creation for incremental build
  kbuild: create object directories simpler and faster
  kbuild: filter-out PHONY targets from "targets"
  kbuild: remove redundant $(wildcard ...) for cmd_files calculation
  kbuild: create directory for make cache only when necessary
  sh: select KBUILD_DEFCONFIG depending on ARCH
  kbuild: fix linker feature test macros when cross compiling with Clang
  kbuild: shrink .cache.mk when it exceeds 1000 lines
  kbuild: do not call cc-option before KBUILD_CFLAGS initialization
  kbuild: Cache a few more calls to the compiler
  kbuild: Add a cache for generated variables
  kbuild: add forward declaration of default target to Makefile.asm-generic
  kbuild: remove KBUILD_SUBDIR_ASFLAGS and KBUILD_SUBDIR_CCFLAGS
  hexagon/kbuild: replace CFLAGS_MODULE with KBUILD_CFLAGS_MODULE
  ...
2017-11-17 17:45:29 -08:00
Masahiro Yamada
8a78756eb5 kbuild: create object directories simpler and faster
For the out-of-tree build, scripts/Makefile.build creates output
directories, but this operation is not efficient.

scripts/Makefile.lib calculates obj-dirs as follows:

  obj-dirs := $(dir $(multi-objs) $(obj-y))

Please notice $(sort ...) is not used here.  Usually the result is
as many "./" as objects here.

For a lot of duplicated paths, the following command is invoked.

  _dummy := $(foreach d,$(obj-dirs), $(shell [ -d $(d) ] || mkdir -p $(d)))

Then, the costly shell command is run over and over again.

I see many points for optimization:

[1] Use $(sort ...) to cut down duplicated paths before passing them
    to system call
[2] Use single $(shell ...) instead of repeating it with $(foreach ...)
    This will reduce forking.
[3] We can calculate obj-dirs more simply.  Most of objects are already
    accumulated in $(targets).  So, $(dir $(targets)) is fine and more
    comprehensive.

I also removed ugly code in arch/x86/entry/vdso/Makefile.  This is now
really unnecessary.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Douglas Anderson <dianders@chromium.org>
2017-11-16 09:07:35 +09:00