linux/arch/sh
Masahiro Yamada 15d5761ad3 kbuild: introduce ccflags-remove-y and asflags-remove-y
CFLAGS_REMOVE_<file>.o filters out flags when compiling a particular
object, but there is no convenient way to do that for every object in
a directory.

Add ccflags-remove-y and asflags-remove-y to make it easily.

Use ccflags-remove-y to clean up some Makefiles.

The add/remove order works as follows:

 [1] KBUILD_CFLAGS specifies compiler flags used globally

 [2] ccflags-y adds compiler flags for all objects in the
     current Makefile

 [3] ccflags-remove-y removes compiler flags for all objects in the
     current Makefile (New feature)

 [4] CFLAGS_<file> adds compiler flags per file.

 [5] CFLAGS_REMOVE_<file> removes compiler flags per file.

Having [3] before [4] allows us to remove flags from most (but not all)
objects in the current Makefile.

For example, kernel/trace/Makefile removes $(CC_FLAGS_FTRACE)
from all objects in the directory, then adds it back to
trace_selftest_dynamic.o and CFLAGS_trace_kprobe_selftest.o

The same applies to lib/livepatch/Makefile.

Please note ccflags-remove-y has no effect to the sub-directories.
In contrast, the previous notation got rid of compiler flags also from
all the sub-directories.

The following are not affected because they have no sub-directories:

  arch/arm/boot/compressed/
  arch/powerpc/xmon/
  arch/sh/
  kernel/trace/

However, lib/ has several sub-directories.

To keep the behavior, I added ccflags-remove-y to all Makefiles
in subdirectories of lib/, except the following:

  lib/vdso/Makefile        - Kbuild does not descend into this Makefile
  lib/raid/test/Makefile   - This is not used for the kernel build

I think commit 2464a609de ("ftrace: do not trace library functions")
excluded too much. In the next commit, I will remove ccflags-remove-y
from the sub-directories of lib/.

Suggested-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Acked-by: Brendan Higgins <brendanhiggins@google.com> (KUnit)
Tested-by: Anders Roxell <anders.roxell@linaro.org>
2020-08-10 01:32:59 +09:00
..
boards clk: Allow the common clk framework to be selectable 2020-05-05 12:34:11 -07:00
boot kbuild: introduce ccflags-remove-y and asflags-remove-y 2020-08-10 01:32:59 +09:00
cchips treewide: replace '---help---' in Kconfig files with 'help' 2020-06-14 01:57:21 +09:00
configs sh: configs: Cleanup old Kconfig IO scheduler options 2020-06-01 14:48:48 -04:00
drivers sh: remove sh5 support 2020-06-01 14:48:52 -04:00
include mm: consolidate pte_index() and pte_offset_*() definitions 2020-06-09 09:39:14 -07:00
kernel maccess: rename probe_kernel_address to get_kernel_nofault 2020-06-18 11:14:40 -07:00
lib sh: add missing EXPORT_SYMBOL() for __delay 2020-06-01 14:48:51 -04:00
math-emu Merge branch 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2019-07-08 21:48:15 -07:00
mm treewide: replace '---help---' in Kconfig files with 'help' 2020-06-14 01:57:21 +09:00
oprofile treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
tools kbuild: remove redundant target cleaning on failure 2019-01-06 09:46:51 +09:00
Kconfig treewide: replace '---help---' in Kconfig files with 'help' 2020-06-14 01:57:21 +09:00
Kconfig.cpu sh: remove sh5 support 2020-06-01 14:48:52 -04:00
Kconfig.debug sh: remove sh5 support 2020-06-01 14:48:52 -04:00
Makefile sh: remove sh5 support 2020-06-01 14:48:52 -04:00