linux-toradex.git/scripts/Makefile.modpost, branch toradex_5.3.y

kbuild: revive single target %.ko

2019-08-09T16:40:25+00:00

I removed the single target %.ko in commit ff9b45c55b26 ("kbuild:
modpost: read modules.order instead of $(MODVERDIR)/*.mod") because
the modpost stage does not work reliably. For instance, the module
dependency, modversion, etc. do not work if we lack symbol information
from the other modules.

Yet, some people still want to build only one module in their interest,
and it may be still useful if it is used within those limitations.

Fixes: ff9b45c55b26 ("kbuild: modpost: read modules.order instead of $(MODVERDIR)/*.mod")
Reported-by: Don Brace 
Reported-by: Arend Van Spriel 
Signed-off-by: Masahiro Yamada

kbuild: modpost: do not parse unnecessary rules for vmlinux modpost

2019-07-31T15:09:49+00:00

Since commit ff9b45c55b26 ("kbuild: modpost: read modules.order instead
of $(MODVERDIR)/*.mod"), 'make vmlinux' emits a warning, like this:

$ make defconfig vmlinux
  [ snip ]
  LD      vmlinux.o
cat: modules.order: No such file or directory
  MODPOST vmlinux.o
  MODINFO modules.builtin.modinfo
  KSYM    .tmp_kallsyms1.o
  KSYM    .tmp_kallsyms2.o
  LD      vmlinux
  SORTEX  vmlinux
  SYSMAP  System.map

When building only vmlinux, KBUILD_MODULES is not set. Hence, the
modules.order is not generated. For the vmlinux modpost, it is not
necessary at all.

Separate scripts/Makefile.modpost for the vmlinux/modules stages.
This works more efficiently because the vmlinux modpost does not
need to include .*.cmd files.

Fixes: ff9b45c55b26 ("kbuild: modpost: read modules.order instead of $(MODVERDIR)/*.mod")
Signed-off-by: Masahiro Yamada

kbuild: modpost: remove unnecessary dependency for __modpost

2019-07-31T15:09:49+00:00

__modpost is a phony target. The dependency on FORCE is pointless.
All the objects have been built in the previous stage, so the
dependency on the objects are not necessary either.

Count the number of modules in a more straightforward way.

Signed-off-by: Masahiro Yamada

kbuild: modpost: handle KBUILD_EXTRA_SYMBOLS only for external modules

2019-07-31T15:09:49+00:00

KBUILD_EXTRA_SYMBOLS makes sense only when building external modules.
Moreover, the modpost sets 'external_module' if the -e option is given.

I replaced $(patsubst %, -e %,...) with simpler $(addprefix -e,...)
while I was here.

Signed-off-by: Masahiro Yamada

kbuild: modpost: include .*.cmd files only when targets exist

2019-07-31T15:09:49+00:00

If a build rule fails, the .DELETE_ON_ERROR special target removes the
target, but does nothing for the .*.cmd file, which might be corrupted.
So, .*.cmd files should be included only when the corresponding targets
exist.

Commit 392885ee82d3 ("kbuild: let fixdep directly write to .*.cmd
files") missed to fix up this file.

Fixes: 392885ee82d3 ("kbuild: let fixdep directly write to .*.cmd")
Cc:  # v5.0+
Signed-off-by: Masahiro Yamada

kbuild: create *.mod with full directory path and remove MODVERDIR

2019-07-17T17:19:31+00:00

While descending directories, Kbuild produces objects for modules,
but do not link final *.ko files; it is done in the modpost.

To keep track of modules, Kbuild creates a *.mod file in $(MODVERDIR)
for every module it is building. Some post-processing steps read the
necessary information from *.mod files. This avoids descending into
directories again. This mechanism was introduced in 2003 or so.

Later, commit 551559e13af1 ("kbuild: implement modules.order") added
modules.order. So, we can simply read it out to know all the modules
with directory paths. This is easier than parsing the first line of
*.mod files.

$(MODVERDIR) has a flat directory structure, that is, *.mod files
are named only with base names. This is based on the assumption that
the module name is unique across the tree. This assumption is really
fragile.

Stephen Rothwell reported a race condition caused by a module name
conflict:

  https://lkml.org/lkml/2019/5/13/991

In parallel building, two different threads could write to the same
$(MODVERDIR)/*.mod simultaneously.

Non-unique module names are the source of all kind of troubles, hence
commit 3a48a91901c5 ("kbuild: check uniqueness of module names")
introduced a new checker script.

However, it is still fragile in the build system point of view because
this race happens before scripts/modules-check.sh is invoked. If it
happens again, the modpost will emit unclear error messages.

To fix this issue completely, create *.mod with full directory path
so that two threads never attempt to write to the same file.

$(MODVERDIR) is no longer needed.

Since modules with directory paths are listed in modules.order, Kbuild
is still able to find *.mod files without additional descending.

I also killed cmd_secanalysis; scripts/mod/sumversion.c computes MD4 hash
for modules with MODULE_VERSION(). When CONFIG_DEBUG_SECTION_MISMATCH=y,
it occurs not only in the modpost stage, but also during directory
descending, where sumversion.c may parse stale *.mod files. It would emit
'No such file or directory' warning when an object consisting a module is
renamed, or when a single-obj module is turned into a multi-obj module or
vice versa.

Signed-off-by: Masahiro Yamada 
Acked-by: Nicolas Pitre

kbuild: modpost: read modules.order instead of $(MODVERDIR)/*.mod

2019-07-17T17:16:27+00:00

Towards the goal of removing MODVERDIR, read out modules.order to get
the list of modules to be processed. This is simpler than parsing *.mod
files in $(MODVERDIR).

For external modules, $(KBUILD_EXTMOD)/modules.order should be read.

I removed the single target %.ko from the top Makefile. To make sure
modpost works correctly, vmlinux and the other modules must be built.
You cannot build a particular .ko file alone.

Signed-off-by: Masahiro Yamada

modpost: make KBUILD_MODPOST_WARN also configurable for external modules

2019-04-11T14:11:51+00:00

Commit ea837f1c0503 ("kbuild: make modpost processing configurable")
was intended to give KBUILD_MODPOST_WARN flexibility to be configurable.
Right now KBUILD_MODPOST_WARN gets just ignored when KBUILD_EXTMOD is
set which happens per default when building modules out of the tree.

This change gives the opportunity to define module build behaving also
in case of out of tree builds and default will become exit on error.
Errors which can be detected by the build should be trapped out of the box
there, unless somebody wants to notice broken stuff later at runtime.

As this patch changes the default behaving from warning to error,
users can consider to fix it for external module builds by:
- providing module symbol table via KBUILD_EXTRA_SYMBOLS for
  modules which are dependent
- OR getting old behaving back by passing KBUILD_MODPOST_WARN to the build

Signed-off-by: Wladislav Wiebe 
Signed-off-by: Masahiro Yamada

modpost: always show verbose warning for section mismatch

2019-03-13T17:39:09+00:00

Unless CONFIG_DEBUG_SECTION_MISMATCH is enabled, modpost only shows
the number of section mismatches.

If you want to know the symbols causing the issue, you need to rebuild
with CONFIG_DEBUG_SECTION_MISMATCH. It is tedious.

I think it is fine to show annoying warning when a new section mismatch
comes in.

Signed-off-by: Masahiro Yamada

kbuild: add real-prereqs shorthand for $(filter-out FORCE,$^)

2019-01-28T00:11:17+00:00

In Kbuild, if_changed and friends must have FORCE as a prerequisite.

Hence, $(filter-out FORCE,$^) or $(filter-out $(PHONY),$^) is a common
idiom to get the names of all the prerequisites except phony targets.

Add real-prereqs as a shorthand.

Note:
We cannot replace $(filter %.o,$^) in cmd_link_multi-m because $^ may
include auto-generated dependencies from the .*.cmd file when a single
object module is changed into a multi object module. Refer to commit
69ea912fda74 ("kbuild: remove unneeded link_multi_deps"). I added some
comment to avoid accidental breakage.

Signed-off-by: Masahiro Yamada 
Acked-by: Rob Herring