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Explicitly allowing specific initializer overrides #639
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feature-request
Not a bug per-se
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fengguang
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Aug 29, 2019
When compiling a kernel with W=1, there are several of those warnings due to arm64 override a field by purpose. Just disable those warnings for both GCC and Clang of this file, so it will help dig "gems" hidden in the W=1 warnings by reducing some noises. mm/init-mm.c:39:2: warning: initializer overrides prior initialization of this subobject [-Winitializer-overrides] INIT_MM_CONTEXT(init_mm) ^~~~~~~~~~~~~~~~~~~~~~~~ ./arch/arm64/include/asm/mmu.h:133:9: note: expanded from macro 'INIT_MM_CONTEXT' .pgd = init_pg_dir, ^~~~~~~~~~~ mm/init-mm.c:30:10: note: previous initialization is here .pgd = swapper_pg_dir, ^~~~~~~~~~~~~~ Note: there is a side project trying to support explicitly allowing specific initializer overrides in Clang, but there is no guarantee it will happen or not. ClangBuiltLinux#639 Signed-off-by: Qian Cai <cai@lca.pw>
rgushchin
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Sep 5, 2019
When compiling a kernel with W=1, there are several of those warnings due to arm64 overriding a field on purpose. Just disable those warnings for both GCC and Clang of this file, so it will help dig "gems" hidden in the W=1 warnings by reducing some noises. mm/init-mm.c:39:2: warning: initializer overrides prior initialization of this subobject [-Winitializer-overrides] INIT_MM_CONTEXT(init_mm) ^~~~~~~~~~~~~~~~~~~~~~~~ ./arch/arm64/include/asm/mmu.h:133:9: note: expanded from macro 'INIT_MM_CONTEXT' .pgd = init_pg_dir, ^~~~~~~~~~~ mm/init-mm.c:30:10: note: previous initialization is here .pgd = swapper_pg_dir, ^~~~~~~~~~~~~~ Note: there is a side project trying to support explicitly allowing specific initializer overrides in Clang, but there is no guarantee it will happen or not. ClangBuiltLinux#639 Link: http://lkml.kernel.org/r/1566920867-27453-1-git-send-email-cai@lca.pw Signed-off-by: Qian Cai <cai@lca.pw> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
fengguang
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to 0day-ci/linux
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Sep 24, 2019
When compiling a kernel with W=1, there are several of those warnings due to arm64 overriding a field on purpose. Just disable those warnings for both GCC and Clang of this file, so it will help dig "gems" hidden in the W=1 warnings by reducing some noises. mm/init-mm.c:39:2: warning: initializer overrides prior initialization of this subobject [-Winitializer-overrides] INIT_MM_CONTEXT(init_mm) ^~~~~~~~~~~~~~~~~~~~~~~~ ./arch/arm64/include/asm/mmu.h:133:9: note: expanded from macro 'INIT_MM_CONTEXT' .pgd = init_pg_dir, ^~~~~~~~~~~ mm/init-mm.c:30:10: note: previous initialization is here .pgd = swapper_pg_dir, ^~~~~~~~~~~~~~ Note: there is a side project trying to support explicitly allowing specific initializer overrides in Clang, but there is no guarantee it will happen or not. ClangBuiltLinux#639 Link: http://lkml.kernel.org/r/1566920867-27453-1-git-send-email-cai@lca.pw Signed-off-by: Qian Cai <cai@lca.pw> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
torvalds
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Sep 25, 2019
When compiling a kernel with W=1, there are several of those warnings due to arm64 overriding a field on purpose. Just disable those warnings for both GCC and Clang of this file, so it will help dig "gems" hidden in the W=1 warnings by reducing some noises. mm/init-mm.c:39:2: warning: initializer overrides prior initialization of this subobject [-Winitializer-overrides] INIT_MM_CONTEXT(init_mm) ^~~~~~~~~~~~~~~~~~~~~~~~ ./arch/arm64/include/asm/mmu.h:133:9: note: expanded from macro 'INIT_MM_CONTEXT' .pgd = init_pg_dir, ^~~~~~~~~~~ mm/init-mm.c:30:10: note: previous initialization is here .pgd = swapper_pg_dir, ^~~~~~~~~~~~~~ Note: there is a side project trying to support explicitly allowing specific initializer overrides in Clang, but there is no guarantee it will happen or not. ClangBuiltLinux#639 Link: http://lkml.kernel.org/r/1566920867-27453-1-git-send-email-cai@lca.pw Signed-off-by: Qian Cai <cai@lca.pw> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
b57a775 landed in 5.4 |
There are only a handful such warnings that remain in the kernel, in particular for drivers/ide. Need to rebase an old patch of mine to turn that off as well. |
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-Winitializer-overrides
/-Woverride-init
tends to get disabled because it is seen as noisy:https://lore.kernel.org/lkml/20190806193434.965-1-cai@lca.pw/
https://lore.kernel.org/lkml/20190807105307.GB54191@lakrids.cambridge.arm.com/
Mark Rutland requested some attribute or intrinsic that would make it clear to the developer and clang that an override was intended so that the warning could be silenced on a per-assignment basis; this would allow a range initializer to be used but individual members could be selectively overridden.
See his email for more information:
https://lore.kernel.org/lkml/20190809083251.GA48423@lakrids.cambridge.arm.com/
This issue is to gather initial feedback into how possible/feasible this is then file an LLVM bug.
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