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authorNick Desaulniers <ndesaulniers@google.com>2021-02-05 12:22:19 -0800
committerMasahiro Yamada <masahiroy@kernel.org>2021-02-16 12:01:45 +0900
commita66049e2cf0ef166dba5bafdbb3062287fc965ad (patch)
tree5685f74e33f09e2d45315c7df5143aef9d567614 /Makefile
parent3c4fa46b30c551b1df2fb1574a684f68bc22067c (diff)
downloadlwn-a66049e2cf0ef166dba5bafdbb3062287fc965ad.tar.gz
lwn-a66049e2cf0ef166dba5bafdbb3062287fc965ad.zip
Kbuild: make DWARF version a choice
Adds a default CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT which allows the implicit default version of DWARF emitted by the toolchain to progress over time. Modifies CONFIG_DEBUG_INFO_DWARF4 to be a member of a choice, making it mutually exclusive with CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT. Users may want to select this if they are using a newer toolchain, but have consumers of the DWARF debug info that aren't yet ready for newer DWARF versions' debug info. Does so in a way that's forward compatible with existing configs, and makes adding future versions more straightforward. This patch does not change the current behavior or selection of DWARF version for users upgrading to kernels with this patch. GCC since ~4.8 has defaulted to DWARF v4 implicitly, and GCC 11 has bumped this to v5. Remove the Kconfig help text about DWARF v4 being larger. It's empirically false for the latest toolchains for x86_64 defconfig, has no point of reference (I suspect it was DWARF v2 but that's stil empirically false), and debug info size is not a qualatative measure. Suggested-by: Arvind Sankar <nivedita@alum.mit.edu> Suggested-by: Fangrui Song <maskray@google.com> Suggested-by: Jakub Jelinek <jakub@redhat.com> Suggested-by: Mark Wielaard <mark@klomp.org> Suggested-by: Masahiro Yamada <masahiroy@kernel.org> Suggested-by: Nathan Chancellor <nathan@kernel.org> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Diffstat (limited to 'Makefile')
-rw-r--r--Makefile5
1 files changed, 3 insertions, 2 deletions
diff --git a/Makefile b/Makefile
index c1cac349ba4e..c567c4343880 100644
--- a/Makefile
+++ b/Makefile
@@ -830,8 +830,9 @@ ifneq ($(LLVM_IAS),1)
KBUILD_AFLAGS += -Wa,-gdwarf-2
endif
-ifdef CONFIG_DEBUG_INFO_DWARF4
-DEBUG_CFLAGS += -gdwarf-4
+ifndef CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT
+dwarf-version-$(CONFIG_DEBUG_INFO_DWARF4) := 4
+DEBUG_CFLAGS += -gdwarf-$(dwarf-version-y)
endif
ifdef CONFIG_DEBUG_INFO_REDUCED