linux-stable/scripts/Makefile.debug
Nick Desaulniers 9f8fe64779 Makefile.debug: support for -gz=zstd
Make DEBUG_INFO_COMPRESSED a choice; DEBUG_INFO_COMPRESSED_NONE is the
default, DEBUG_INFO_COMPRESSED_ZLIB uses zlib,
DEBUG_INFO_COMPRESSED_ZSTD uses zstd.

This renames the existing KConfig option DEBUG_INFO_COMPRESSED to
DEBUG_INFO_COMPRESSED_ZLIB so users upgrading may need to reset the new
Kconfigs.

Some quick N=1 measurements with du, /usr/bin/time -v, and bloaty:

clang-16, x86_64 defconfig plus
CONFIG_DEBUG_INFO=y CONFIG_DEBUG_INFO_COMPRESSED_NONE=y:
Elapsed (wall clock) time (h:mm:ss or m:ss): 0:55.43
488M vmlinux
27.6%   136Mi   0.0%       0    .debug_info
 6.1%  30.2Mi   0.0%       0    .debug_str_offsets
 3.5%  17.2Mi   0.0%       0    .debug_line
 3.3%  16.3Mi   0.0%       0    .debug_loclists
 0.9%  4.62Mi   0.0%       0    .debug_str

clang-16, x86_64 defconfig plus
CONFIG_DEBUG_INFO=y CONFIG_DEBUG_INFO_COMPRESSED_ZLIB=y:
Elapsed (wall clock) time (h:mm:ss or m:ss): 1:00.35
385M vmlinux
21.8%  85.4Mi   0.0%       0    .debug_info
 2.1%  8.26Mi   0.0%       0    .debug_str_offsets
 2.1%  8.24Mi   0.0%       0    .debug_loclists
 1.9%  7.48Mi   0.0%       0    .debug_line
 0.5%  1.94Mi   0.0%       0    .debug_str

clang-16, x86_64 defconfig plus
CONFIG_DEBUG_INFO=y CONFIG_DEBUG_INFO_COMPRESSED_ZSTD=y:
Elapsed (wall clock) time (h:mm:ss or m:ss): 0:59.69
373M vmlinux
21.4%  81.4Mi   0.0%       0    .debug_info
 2.3%  8.85Mi   0.0%       0    .debug_loclists
 1.5%  5.71Mi   0.0%       0    .debug_line
 0.5%  1.95Mi   0.0%       0    .debug_str_offsets
 0.4%  1.62Mi   0.0%       0    .debug_str

That's only a 3.11% overall binary size savings over zlib, but at no
performance regression.

Link: https://maskray.me/blog/2022-09-09-zstd-compressed-debug-sections
Link: https://maskray.me/blog/2022-01-23-compressed-debug-sections
Suggested-by: Sedat Dilek (DHL Supply Chain) <sedat.dilek@dhl.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2022-11-21 10:18:39 +09:00

44 lines
1.1 KiB
Text

DEBUG_CFLAGS :=
DEBUG_RUSTFLAGS :=
debug-flags-y := -g
ifdef CONFIG_DEBUG_INFO_SPLIT
DEBUG_CFLAGS += -gsplit-dwarf
endif
debug-flags-$(CONFIG_DEBUG_INFO_DWARF4) += -gdwarf-4
debug-flags-$(CONFIG_DEBUG_INFO_DWARF5) += -gdwarf-5
ifeq ($(CONFIG_CC_IS_CLANG)$(CONFIG_AS_IS_GNU),yy)
# Clang does not pass -g or -gdwarf-* option down to GAS.
# Add -Wa, prefix to explicitly specify the flags.
KBUILD_AFLAGS += $(addprefix -Wa$(comma), $(debug-flags-y))
endif
DEBUG_CFLAGS += $(debug-flags-y)
KBUILD_AFLAGS += $(debug-flags-y)
ifdef CONFIG_DEBUG_INFO_REDUCED
DEBUG_CFLAGS += -fno-var-tracking
DEBUG_RUSTFLAGS += -Cdebuginfo=1
ifdef CONFIG_CC_IS_GCC
DEBUG_CFLAGS += -femit-struct-debug-baseonly
endif
else
DEBUG_RUSTFLAGS += -Cdebuginfo=2
endif
ifdef CONFIG_DEBUG_INFO_COMPRESSED_ZLIB
DEBUG_CFLAGS += -gz=zlib
KBUILD_AFLAGS += -gz=zlib
KBUILD_LDFLAGS += --compress-debug-sections=zlib
else ifdef CONFIG_DEBUG_INFO_COMPRESSED_ZSTD
DEBUG_CFLAGS += -gz=zstd
KBUILD_AFLAGS += -gz=zstd
KBUILD_LDFLAGS += --compress-debug-sections=zstd
endif
KBUILD_CFLAGS += $(DEBUG_CFLAGS)
export DEBUG_CFLAGS
KBUILD_RUSTFLAGS += $(DEBUG_RUSTFLAGS)
export DEBUG_RUSTFLAGS