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commit8f6629c004upstream. -Wenum-enum-conversion was strengthened in clang-19 to warn for C, which caused the kernel to move it to W=1 in commit75b5ab134b("kbuild: Move -Wenum-{compare-conditional,enum-conversion} into W=1") because there were numerous instances that would break builds with -Werror. Unfortunately, this is not a full solution, as more and more developers, subsystems, and distributors are building with W=1 as well, so they continue to see the numerous instances of this warning. Since the move to W=1, there have not been many new instances that have appeared through various build reports and the ones that have appeared seem to be following similar existing patterns, suggesting that most instances of this warning will not be real issues. The only alternatives for silencing this warning are adding casts (which is generally seen as an ugly practice) or refactoring the enums to macro defines or a unified enum (which may be undesirable because of type safety in other parts of the code). Move the warning to W=2, where warnings that occur frequently but may be relevant should reside. Cc: stable@vger.kernel.org Fixes:75b5ab134b("kbuild: Move -Wenum-{compare-conditional,enum-conversion} into W=1") Link: https://lore.kernel.org/ZwRA9SOcOjjLJcpi@google.com/ Signed-off-by: Nathan Chancellor <nathan@kernel.org> Acked-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
200 lines
6.5 KiB
Makefile
200 lines
6.5 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0
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# ==========================================================================
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# make W=... settings
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#
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# There are four warning groups enabled by W=1, W=2, W=3, and W=e
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# They are independent, and can be combined like W=12 or W=123e.
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# ==========================================================================
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# Default set of warnings, always enabled
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KBUILD_CFLAGS += -Wall
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KBUILD_CFLAGS += -Wundef
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KBUILD_CFLAGS += -Werror=implicit-function-declaration
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KBUILD_CFLAGS += -Werror=implicit-int
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KBUILD_CFLAGS += -Werror=return-type
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KBUILD_CFLAGS += -Werror=strict-prototypes
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KBUILD_CFLAGS += -Wno-format-security
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KBUILD_CFLAGS += -Wno-trigraphs
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KBUILD_CFLAGS += $(call cc-disable-warning,frame-address,)
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KBUILD_CFLAGS += $(call cc-disable-warning, address-of-packed-member)
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KBUILD_CFLAGS += -Wmissing-declarations
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KBUILD_CFLAGS += -Wmissing-prototypes
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ifneq ($(CONFIG_FRAME_WARN),0)
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KBUILD_CFLAGS += -Wframe-larger-than=$(CONFIG_FRAME_WARN)
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endif
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KBUILD_CPPFLAGS-$(CONFIG_WERROR) += -Werror
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KBUILD_CPPFLAGS += $(KBUILD_CPPFLAGS-y)
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KBUILD_CFLAGS-$(CONFIG_CC_NO_ARRAY_BOUNDS) += -Wno-array-bounds
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ifdef CONFIG_CC_IS_CLANG
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# The kernel builds with '-std=gnu11' so use of GNU extensions is acceptable.
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KBUILD_CFLAGS += -Wno-gnu
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else
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# gcc inanely warns about local variables called 'main'
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KBUILD_CFLAGS += -Wno-main
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endif
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# These result in bogus false positives
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KBUILD_CFLAGS += $(call cc-disable-warning, dangling-pointer)
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# Variable Length Arrays (VLAs) should not be used anywhere in the kernel
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KBUILD_CFLAGS += -Wvla
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# disable pointer signed / unsigned warnings in gcc 4.0
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KBUILD_CFLAGS += -Wno-pointer-sign
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# In order to make sure new function cast mismatches are not introduced
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# in the kernel (to avoid tripping CFI checking), the kernel should be
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# globally built with -Wcast-function-type.
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KBUILD_CFLAGS += $(call cc-option, -Wcast-function-type)
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# The allocators already balk at large sizes, so silence the compiler
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# warnings for bounds checks involving those possible values. While
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# -Wno-alloc-size-larger-than would normally be used here, earlier versions
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# of gcc (<9.1) weirdly don't handle the option correctly when _other_
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# warnings are produced (?!). Using -Walloc-size-larger-than=SIZE_MAX
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# doesn't work (as it is documented to), silently resolving to "0" prior to
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# version 9.1 (and producing an error more recently). Numeric values larger
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# than PTRDIFF_MAX also don't work prior to version 9.1, which are silently
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# ignored, continuing to default to PTRDIFF_MAX. So, left with no other
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# choice, we must perform a versioned check to disable this warning.
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# https://lore.kernel.org/lkml/20210824115859.187f272f@canb.auug.org.au
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KBUILD_CFLAGS-$(call gcc-min-version, 90100) += -Wno-alloc-size-larger-than
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KBUILD_CFLAGS += $(KBUILD_CFLAGS-y) $(CONFIG_CC_IMPLICIT_FALLTHROUGH)
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# Prohibit date/time macros, which would make the build non-deterministic
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KBUILD_CFLAGS += -Werror=date-time
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# enforce correct pointer usage
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KBUILD_CFLAGS += $(call cc-option,-Werror=incompatible-pointer-types)
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# Require designated initializers for all marked structures
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KBUILD_CFLAGS += $(call cc-option,-Werror=designated-init)
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# Warn if there is an enum types mismatch
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KBUILD_CFLAGS += $(call cc-option,-Wenum-conversion)
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KBUILD_CFLAGS += -Wextra
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KBUILD_CFLAGS += -Wunused
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#
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# W=1 - warnings which may be relevant and do not occur too often
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#
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ifneq ($(findstring 1, $(KBUILD_EXTRA_WARN)),)
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KBUILD_CFLAGS += -Wmissing-format-attribute
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KBUILD_CFLAGS += -Wmissing-include-dirs
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KBUILD_CFLAGS += $(call cc-option, -Wunused-const-variable)
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KBUILD_CPPFLAGS += -Wundef
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KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN1
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else
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# Some diagnostics enabled by default are noisy.
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# Suppress them by using -Wno... except for W=1.
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KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable)
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KBUILD_CFLAGS += $(call cc-disable-warning, unused-const-variable)
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KBUILD_CFLAGS += $(call cc-disable-warning, packed-not-aligned)
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KBUILD_CFLAGS += $(call cc-disable-warning, format-overflow)
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ifdef CONFIG_CC_IS_GCC
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KBUILD_CFLAGS += $(call cc-disable-warning, format-truncation)
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else
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# Clang checks for overflow/truncation with '%p', while GCC does not:
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# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111219
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KBUILD_CFLAGS += $(call cc-disable-warning, format-overflow-non-kprintf)
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KBUILD_CFLAGS += $(call cc-disable-warning, format-truncation-non-kprintf)
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endif
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KBUILD_CFLAGS += $(call cc-disable-warning, stringop-truncation)
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KBUILD_CFLAGS += -Wno-override-init # alias for -Wno-initializer-overrides in clang
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ifdef CONFIG_CC_IS_CLANG
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# Clang before clang-16 would warn on default argument promotions.
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ifneq ($(call clang-min-version, 160000),y)
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# Disable -Wformat
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KBUILD_CFLAGS += -Wno-format
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# Then re-enable flags that were part of the -Wformat group that aren't
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# problematic.
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KBUILD_CFLAGS += -Wformat-extra-args -Wformat-invalid-specifier
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KBUILD_CFLAGS += -Wformat-zero-length -Wnonnull
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# Requires clang-12+.
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ifeq ($(call clang-min-version, 120000),y)
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KBUILD_CFLAGS += -Wformat-insufficient-args
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endif
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endif
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KBUILD_CFLAGS += $(call cc-disable-warning, pointer-to-enum-cast)
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KBUILD_CFLAGS += -Wno-tautological-constant-out-of-range-compare
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KBUILD_CFLAGS += $(call cc-disable-warning, unaligned-access)
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KBUILD_CFLAGS += -Wno-enum-compare-conditional
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endif
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endif
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#
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# W=2 - warnings which occur quite often but may still be relevant
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#
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ifneq ($(findstring 2, $(KBUILD_EXTRA_WARN)),)
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KBUILD_CFLAGS += -Wdisabled-optimization
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KBUILD_CFLAGS += -Wshadow
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KBUILD_CFLAGS += $(call cc-option, -Wlogical-op)
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KBUILD_CFLAGS += $(call cc-option, -Wunused-macros)
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KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN2
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else
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# The following turn off the warnings enabled by -Wextra
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KBUILD_CFLAGS += -Wno-missing-field-initializers
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KBUILD_CFLAGS += -Wno-type-limits
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KBUILD_CFLAGS += -Wno-shift-negative-value
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ifdef CONFIG_CC_IS_CLANG
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KBUILD_CFLAGS += -Wno-enum-enum-conversion
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endif
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ifdef CONFIG_CC_IS_GCC
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KBUILD_CFLAGS += -Wno-maybe-uninitialized
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endif
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endif
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#
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# W=3 - more obscure warnings, can most likely be ignored
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#
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ifneq ($(findstring 3, $(KBUILD_EXTRA_WARN)),)
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KBUILD_CFLAGS += -Wbad-function-cast
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KBUILD_CFLAGS += -Wcast-align
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KBUILD_CFLAGS += -Wcast-qual
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KBUILD_CFLAGS += -Wconversion
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KBUILD_CFLAGS += -Wpacked
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KBUILD_CFLAGS += -Wpadded
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KBUILD_CFLAGS += -Wpointer-arith
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KBUILD_CFLAGS += -Wredundant-decls
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KBUILD_CFLAGS += -Wsign-compare
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KBUILD_CFLAGS += -Wswitch-default
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KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN3
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else
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# The following turn off the warnings enabled by -Wextra
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KBUILD_CFLAGS += -Wno-sign-compare
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KBUILD_CFLAGS += -Wno-unused-parameter
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endif
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#
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# W=e - error out on warnings
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#
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ifneq ($(findstring e, $(KBUILD_EXTRA_WARN)),)
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KBUILD_CFLAGS += -Werror
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endif
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