kbuild: add infrastructure to build userspace programs ...

Import Linux commit 7f3a59d

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

kbuild: switch over to thin archive ...

Starting v4.13, Linux always uses thin archive instead of relocatable
ELF to combine builtin objects.

The thin archive is basically a text file that only contains paths to
object files.

As Linux commit 98ced886dd79 mentioned, this has a lot of benefits:

 - save disk space for builds

 - speed-up building a little

 - fix some issues when liking a giant executable (for example,
   allyesconfig on ARM Linux)

 - work better with dead code elimination

The last one is important for barebox because pbl highly relies on the
dead code elimination (-f{function,data}-sections and --gc-sections)
dropping symbols that are unreachable from the linker's entry point.
The dead code elimination does not work if the same symbol names are
used in the pevious incremental link mechanism because the same name
symbols all go into the same section.

Commit a83c97f2a406 ("ARM: socfpga: generate smaller images when
multiple boards are selected") worked around it by giving a dedicate
section to each of the same name symbols. This workaround can go away.

built-in.o was renamed to built-in.a since it is now an archive.
built-in-pbl.o was renamed to built-in.pbl.a for consistency.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

kbuild: unify barebox and pbl build commands ...

The current Linux uses the unified build command for built-in objects
and module objects. This is possible because part-of-module is set to
y when the target is being built for a module. If so, quiet_modtag is
set to [M], and modkern_cflags is set to KBUILD_CFLAGS_MODULE instead
of KBUILD_CFLAGS_KERNEL.

Currently, barebox uses a separate build command for pbl, but the
difference between cmd_cc_o_c and cmd_pbl_cc_o_c is just
"-D__PBL__ $(PBL_CPPFLAGS)".

By using the same approach as Linux, they can be unified.

Set part-of-pbl flag to y when the target is being built for pbl.
Merge cmd_as_o_S and cmd_link_o_target as well.

This also changes the shortlog style as follows:

  PBLCC  ->  CC [P]
  PBLAS  ->  AS [P]
  PBLLD  ->  LD [P]

This is more consistent with the policy in the Linux build system.

In Linux, a capital letter enclosed square blackets indicates which
target the object is being built for.

  CC      object built for built-in
  CC [M]  object built for modules
  CC [U]  object built for userspace (proposed for Linux 5.8-rc1)

The idea behind this is we use the same compiler $(CC) for them.
Only the difference is the compiler flags. On the other hand, host
programs are compiled by a different tool, $(HOSTCC), hence the
shortlog is 'HOSTCC'.

Barebox supports module builds (it seems), but the [P] notation does
not conflict with [M] because pbl has a limited memory footprint.
We never expect pbl can support the module feature.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

kbuild: resync modkern_{c, a}flags and quiet_modtag with Linux 5.7-rc6 ...

The latest Linux calculates them more simply; part-of-module is set
when the target is being built for a module.

Also, rename real-objs-{y,m} to real-obj-{y,m}.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

kbuild: resync mkdir code with Linux 5.7-rc6 ...

Kbuild automatically creates the output directories for O= builds.
Previously it called mkdir too much. Linux optimized this a lot.
Let's import the outcome so it works faster.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

kbuild: remove obj-dtb-y, pbl-dtb-y, lwl-dtb-y syntax ...

The embedded DTBs are compiled by the chain of pattern rules as follows:

  %.dts -> %.dtb -> %.dtb.S -> %.dtb.o       for barebox proper
  %.dts -> %.dtb -> %.dtb.S -> %.dtb.pbl.o   for pbl

Barebox introduced {obj,pbl,lwl}-dtb-y syntax to put the intermediate
files into extra-y. The purposes of doing so were:

 [1] prevent GNU Make from deleting the intermediate files
 [2] include .*.cmd files

In contrast, Linux does not use a special syntax for embedding DTBs
into the kernel.

For example, as you see in arch/sh/boot/dts/Makefile of Linux 5.6,

   obj-y += <basename>.dtb.o

... just works.

This is because scripts/Kbuild.include specifies .SECONDARY to cater
to [1], and scripts/Makefile.build adds the intermediates to 'targets'
to deal with [2].

Barebox had already imported the same code from Linux, so you can use
obj-y instead of obj-dtb-y, like Linux.

pbl-dtb-y and lwl-dtb-y are barebox-specific cases, so I added the
%.dtb.pbl.o pattern to intermediate_targets.

Going forward, please use obj-y, pbl-y, or lwl-y.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

kbuild: rename pbl object pbl-*.o to *.pbl.o ...

Currently, pbl objects are output to:

  <directory-path>/pbl-<basename>.o

This commit changes as follows:

  <directory-path>/<basename>.pbl.o

The motivation is not only to get rid of the ugly code introduced by
commit 257abdaa36c8 ("Do not rm the path from pbl-y target"), but also
to make it easier to remove obj-dtb-y, pbl-dtb-y, lwl-dtb-y syntax in
the next commit.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Merge branch 'for-next/kbuild'

kbuild: resync top Makefile, mkmakefile, tags.sh with Linux 5.7-rc4 ...

The prologue of the build system is not specific to Linux or Barebox.
Paritially resync with Linux 5.7-rc4

- In Linux, $(objtree) is always '.', and $(srctree) might be relative.
  I am keeping both absolute for now to avoid unexpected breakage.

- I did not resync single target for now. We need to touch
  Makefile.build a lot if we want to resync it.

- 'export CDPATH=' is Barebox-only code, which was added by
  commit 6cc8d0544658 ("Makefile: disable CDPATH"). Keep it.

- KBUILD_SRC no longer exists in the upstream Linux. I replaced it
  with building_out_of_srctree.

- scripts/mkmakefile does not contain anything specific to Linux or
  Barebox. Resync it with Linux 5.7-rc4

- scripts/tags was imported from Linux 3.6 with some cherry-picks on
  top of that. Resync it with Linux 5.7-rc4

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

kbuild: sync if_changed and friends with Linux 5.7-rc2 ...

Resync cmd, if_change, if_changed_dep, and if_changed_rule.

Clean up the users of if_changed_rule.

I deleted the modversions rule. It is dead code because barebox
does not define CONFIG_MODVERSIONS. It does not work without
scripts/genksyms/ anyway.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

kbuild: add $(always-y) to 'targets' ...

I missed to sync this line in commit 421108c51da4 ("kbuild: rename
hostprogs-y/always to hostprogs/always-y").

Since then, the files in always(-y) are needlessly rebuilt.

Fixes: 421108c51da4 ("kbuild: rename hostprogs-y/always to hostprogs/always-y")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

kbuild: use $(SRCARCH) to point to the arch directory ...

A couple of arch directories in Linux are biarch, that is, a single
arch/*/ directory supports both 32-bit and 64-bit.

In old days of Linux, they started as separated directories.
arm/arm64 is the exceptional case, but the other architectures were
unified.

e.g.)

  arch/i386, arch/x86_64    ->  arch/x86
  arch/sh, arch/sh64        ->  arch/sh
  arch/sparc, arch/sparc64  ->  arch/sparc

Linux commit 6752ed90da03 ("Kbuild: allow arch/xxx to use a different
source path") introduced SRCARCH to point to the arch directory, still
allowing to pass in the former ARCH=i386 or ARCH=x86_64.

The top Makefile in Linux converts ARCH to SRCARCH as follows:

  # Additional ARCH settings for x86
  ifeq ($(ARCH),i386)
          SRCARCH := x86
  endif
  ifeq ($(ARCH),x86_64)
          SRCARCH := x86
  endif

So, if you follow the upstream Kbuild convention, using arch/$(SRCARCH)
is the correct way to point to the arch directory.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

kbuild: prefix compiler flag variables with KBUILD_ ...

In old days, Linux also used to use well-known variables such CFLAGS,
CPPFLAGS, etc.

They were prefixed with KBUILD_ presumably for preventing users from
overriding them accidentally.

Rename as follows:
  CFLAGS          ->  KBUILD_CFLAGS
  AFLAGS          ->  KBUILD_AFLAGS
  CPPFLAGS        ->  KBUILD_CPPFLAGS
  LDFLAGS         ->  KBUILD_LDFLAGS
  HOSTCFLAGS      ->  KBUILD_HOSTCFLAGS
  HOSTCXXFLAGS    ->  KBUILD_HOSTCXXFLAGS
  HOSTLDFLAGS     ->  KBUILD_HOSTLDFLAGS
  HOST_LOADLIBES  ->  KBUILD_HOSTLDLIBS

HOSTCFLAGS, HOSTCXXFLAGS, HOSTLDFLAGS, HOSTLDLIBS are re-used to allow
users to pass-in additional flags to the host compiler.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

kbuild: rename hostprogs-y/always to hostprogs/always-y ...

[ Linux commit 5f2fb52 ]

In old days, the "host-progs" syntax was used for specifying host
programs. It was renamed to the current "hostprogs-y" in 2004.

It is typically useful in scripts/Makefile because it allows Kbuild to
selectively compile host programs based on the kernel configuration.

This commit renames like follows:

  always       ->  always-y
  hostprogs-y  ->  hostprogs

So, scripts/Makefile will look like this:

  always-$(CONFIG_BUILD_BIN2C) += ...
  always-$(CONFIG_KALLSYMS)    += ...
      ...
  hostprogs := $(always-y) $(always-m)

I think this makes more sense because a host program is always a host
program, irrespective of the kernel configuration. We want to specify
which ones to compile by CONFIG options, so always-y will be handier.

The "always", "hostprogs-y", "hostprogs-m" will be kept for backward
compatibility for a while.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

kbuild: Add missing semicolon ...

Fixes: 4fafb35d925e5 ("kbuild: cherry-pick changes from Linux v5.0-rc3")

The change cherry-picked from the Kernel commit 7d0ea2524202 ("kbuild: use
'else ifeq' for checksrc to improve readability") also removed the
trailing semicolons from the cmd_*checksrc lines. These were removed in
kernel commit e5d289100d ("kbuild: remove trailing semicolon from cmd_*
passed to if_changed_rule"), but seems the barebox Kbuild version is not
yet ready for this change. Without the semicolons a make C=1 build fails
with:

No such file: echo

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>

kbuild: cherry-pick changes from Linux v5.0-rc3 ...

Not synced completely.

Just cherry-picking low-hanging fruits.

  0b35786d77ba  kbuild: call make once for all targets when O=.. is used
  5e54d5e5fbc1  kbuild: kill EXTRA_ARFLAGS
  836caba77c29  kbuild: kill backward compatibility checks
  3156fd0529b5  kbuild: fix some minor typoes
  b8b0618cf6fa  kbuild: remove extra ifdef/endif of top Makefile
  16f890988114  kbuild: Remove reference to uninitialised variable
  9319f4539c18  kbuild: support simultaneous "make %config" and "make all"
  9d5db8949f1e  scripts/Makefile.clean: clean also $(extra-m) and $(extra-)
  a4954fd7724c  kbuild: remove obj-n and lib-n handling
  371fdc77af44  kbuild: collect shorthands into scripts/Kbuild.include
  a29b82326ed4  kbuild: Remove duplicate $(cmd) definition in Makefile.clean
  a1e7b7bb1ab5  Makefile: sort list of defconfig targets in make help output
  34948e0bbf98  kbuild: Drop support for clean-rule
  4218affdf57f  kbuild: remove warning about "make depend"
  9c8fa9bc08f6  kbuild: fix if_change and friends to consider argument order
  39a33ff80a25  kbuild: remove cc-option-align
  a7f924190924  kbuild: add %.dtb.S and %.dtb to 'targets' automatically
  54a702f70589  kbuild: mark $(targets) as .SECONDARY and remove .PRECIOUS markers
  9564a8cf422d  Kbuild: fix # escaping in .cmd files for future Make
  bd412d81b7ea  kbuild: .PHONY is not a variable, but PHONY is
  6916162c7308  kbuild: remove duplicated comments about PHONY
  d6c6ab93e17f  kbuild: remove deprecated host-progs variable
  7d0ea2524202  kbuild: use 'else ifeq' for checksrc to improve readability
  3f80babd9ca4  kbuild: remove unused cc-fullversion variable
  bd352a739fde  kbuild: remove unused baseprereq
  b421b8a6cb87  kbuild: remove unused archmrproper

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

kbuild: add %.lex.c and %.tab.[ch] to 'targets' automatically ...

Linux commit b23d1a2
(adjust commit log for barebox)

This will be needed for Barebox to switch to the compile-time
generation of lexers and parsers.

Files generated by if_changed* must be added to 'targets' to include
*.cmd files.  Otherwise, they would be regenerated every time.

The build system automatically adds objects to 'targets' where
appropriate, such as obj-y, extra-y, etc. but does nothing for
intermediate files.  So, each Makefile needs to add them by itself.

There are some common cases where objects are generated by chained
rules.  Lexers and parsers are compiled like follows:

   %.lex.o <- %.lex.c <- %.l
   %.tab.o <- %.tab.c <- %.y

They are common patterns, so it is reasonable to take care of them
in the core Makefile instead of requiring each Makefile to do so.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

kbuild: filter-out PHONY targets from "targets" ...

Linux commit 591f668

The variable "targets" contains object paths for which existing .*.cmd
files should be included.

scripts/Makefile.build automatically adds $(MAKECMDGOALS) to "targets"
as follows:

  targets += $(extra-y) $(MAKECMDGOALS) $(always)

The $(MAKECMDGOALS) is a PHONY target in several places.  PHONY targets
never create .*.cmd files.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

kbuild: handle multi-objs dependency appropriately ...

The comment in scripts/Makefile.build says as follows:

  We would rather have a list of rules like
        foo.o: $(foo-objs)
  but that's not so easy, so we rather make all composite objects depend
  on the set of all their parts

This commit makes it possible!

For example, assume a Makefile like this

  obj-m = foo.o bar.o
  foo-objs := foo1.o foo2.o
  bar-objs := bar1.o bar2.o

Without this patch, foo.o depends on all of
foo1.o foo2.o bar1.o bar2.o.
It looks funny that foo.o is regenerated when bar1.c is updated.

Now we can handle the dependency of foo.o and bar.o separately.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>

pbl: Fix typo in make causing pbl files to be rebuilt ...

We had pbl_cc__o_c instead of pbl_cc_o_c. This caused all pbl object
files to be rebuilt everytime due to missing .cmd file.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

pbl: Add missing FORCE ...

Otherwise the pbl files do not get rebuilt when the CFLAGS change.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

kbuild: allow to have custom cppflags for pbl ...

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>

kbuild: add pre-bootloader (pbl) target ...

This will allow to link compiled object to the built-in-pbl.o across the source
tree that will be finally link to the pbl.

Now we compile the source %.c in pbl-%.o and provide -D__PBL__
so we can known in the source when it's compile for barebox or the pbl.

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>

kbuild: Init all relevant variables used in kbuild files ...

import from linux 3.5-rc5

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Only pass -P to cpp when generating ld scripts ...

When building sandbox with ccache, one would hit warnings such as:
    warning: 'struct mmsghdr' declared inside parameter list
on random files; a way to reproduce this issue is to build a simple
file doing just:
    #include <sys/socket.h>

    int main(void) {
        return 0;
    }

    gcc -Wall -P -c -o foo foo.c

But actually the -P flag is only useful when generating non-C files,
such as linker scripts in the case of barebox.  Removing the -P flag
from all the gcc invocations, except when generating .lds files makes
the warning go away.  It turns out that this is what
linux/scripts/Makefile.build also does nowadays.

Signed-off-by: Loïc Minier <loic.minier@linaro.org>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

svn_rev_008 ...

add missing Kconfig