Currently, qconf.moc is included from qconf.cc but they can be compiled
independently.

When you modify qconf.cc, qconf.moc does not need recompiling.

Rename qconf.moc to qconf-moc.cc, and split it out as an independent
compilation unit.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

Regenerate qconf.moc when the moc command is changed.

This also allows 'make mrproper' to clean it up. Previously, it was
not cleaned up because 'clean-files += qconf.moc' was missing.
Now 'make mrproper' correctly cleans it up because files listed in
'targets' are cleaned.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

kvmconfig' is a shorthand for kvm_guest.config to save 7 character typing.

xenconfig' is a shorthand for xen.config to save 1 character typing.

There is nothing more than that.

There are more files in kernel/configs/, so it is not maintainable
to wire-up every config fragment to the Kconfig Makefile. Hence,
we should not do this at all.

These will be removed after Linux 5.10. Meanwhile, the following
warning message will be displayed if they are used.

WARNING: 'make kvmconfig' will be removed after Linux 5.10
         Please use 'make kvm_guest.config' instead.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

Sometimes it is useful to preserve batches of configs when making
localmodconfig. For example, I usually don't want any usb and fs
modules to be disabled. Now we can do it by:

 $ make LMC_KEEP="drivers/usb:fs" localmodconfig

Signed-off-by: Changbin Du <changbin.du@gmail.com>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

Most of the Kconfig commands (except defconfig and all*config) read
the .config file as a base set of CONFIG options.

When it does not exist, the files in DEFCONFIG_LIST are searched in
this order and loaded if found.

I do not see much sense in the last two lines in DEFCONFIG_LIST.

[1] ARCH_DEFCONFIG

The entry for DEFCONFIG_LIST is guarded by 'depends on !UML'. So, the
ARCH_DEFCONFIG definition in arch/x86/um/Kconfig is meaningless.

arch/{sh,sparc,x86}/Kconfig define ARCH_DEFCONFIG depending on 32 or
64 bit variant symbols. This is a little bit strange; ARCH_DEFCONFIG
should be a fixed string because the base config file is loaded before
the symbol evaluation stage.

Using KBUILD_DEFCONFIG makes more sense because it is fixed before
Kconfig is invoked. Fortunately, arch/{sh,sparc,x86}/Makefile define it
in the same way, and it works as expected. Hence, replace ARCH_DEFCONFIG
with "arch/$(SRCARCH)/configs/$(KBUILD_DEFCONFIG)".

[2] arch/$(ARCH)/defconfig

This file path is no longer valid. The defconfig files are always located
in the arch configs/ directories.

  $ find arch -name defconfig | sort
  arch/alpha/configs/defconfig
  arch/arm64/configs/defconfig
  arch/csky/configs/defconfig
  arch/nds32/configs/defconfig
  arch/riscv/configs/defconfig
  arch/s390/configs/defconfig
  arch/unicore32/configs/defconfig

The path arch/*/configs/defconfig is already covered by
"arch/$(SRCARCH)/configs/$(KBUILD_DEFCONFIG)". So, this file path is
not necessary.

I moved the default KBUILD_DEFCONFIG to the top Makefile. Otherwise,
the 7 architectures listed above would end up with endless loop of
syncconfig.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

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>

Since kernel configs provided by syzbot are close to "make allyesconfig",
it takes long time to rebuild. This is especially waste of time when we
need to rebuild for many times (e.g. doing manual printk() inspection,
bisect operations).

We can save time if we can exclude modules which are irrelevant to each
problem. But "make localmodconfig" cannot exclude modules which are built
into vmlinux because /sbin/lsmod output is used as the source of modules.

Therefore, this patch adds "make yes2modconfig" which converts from =y
to =m if possible. After confirming that the interested problem is still
reproducible, we can try "make localmodconfig" (and/or manually tune
based on "Modules linked in:" line) in order to exclude modules which are
irrelevant to the interested problem. While we are at it, this patch also
adds "make mod2yesconfig" which converts from =m to =y in case someone
wants to convert from =m to =y after "make localmodconfig".

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

The top Makefile defines and exports the variable 'PERL'. Use it in
case somebody wants to specify a particular version of perl from the
command line.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

The indentation for if ... else ... fi is too deep. Fix it.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

make listnewconfig will list the individual options that need to be set.
This is useful but there's no easy way to get the help text associated
with the options at the same time. Introduce a new targe
'make helpnewconfig' which lists the full help text of all the
new options as well. This makes it easier to automatically generate
changes that are easy for humans to review. This command also adds
markers between each option for easier parsing.

Signed-off-by: Laura Abbott <labbott@redhat.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>