Commit 9f8fe647 authored by Nick Desaulniers's avatar Nick Desaulniers Committed by Masahiro Yamada
Browse files

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: default avatarSedat Dilek (DHL Supply Chain) <sedat.dilek@dhl.com>
Reviewed-by: default avatarNathan Chancellor <nathan@kernel.org>
Signed-off-by: default avatarNick Desaulniers <ndesaulniers@google.com>
Signed-off-by: default avatarMasahiro Yamada <masahiroy@kernel.org>
parent 0d2573a2

lib/Kconfig.debug

+27 −2
Original line number Diff line number Diff line
@@ -312,8 +312,21 @@ config DEBUG_INFO_REDUCED 
	  DEBUG_INFO build and compile times are reduced too.

	  Only works with newer gcc versions.



config DEBUG_INFO_COMPRESSED

	bool "Compressed debugging information"

choice

	prompt "Compressed Debug information"

	help

	  Compress the resulting debug info. Results in smaller debug info sections,

	  but requires that consumers are able to decompress the results.



	  If unsure, choose DEBUG_INFO_COMPRESSED_NONE.



config DEBUG_INFO_COMPRESSED_NONE

	bool "Don't compress debug information"

	help

	  Don't compress debug info sections.



config DEBUG_INFO_COMPRESSED_ZLIB

	bool "Compress debugging information with zlib"

	depends on $(cc-option,-gz=zlib)

	depends on $(ld-option,--compress-debug-sections=zlib)

	help
@@ -327,6 +340,18 @@ config DEBUG_INFO_COMPRESSED 
	  preferable to setting $KDEB_COMPRESS to "none" which would be even

	  larger.



config DEBUG_INFO_COMPRESSED_ZSTD

	bool "Compress debugging information with zstd"

	depends on $(cc-option,-gz=zstd)

	depends on $(ld-option,--compress-debug-sections=zstd)

	help

	  Compress the debug information using zstd.  This may provide better

	  compression than zlib, for about the same time costs, but requires newer

	  toolchain support.  Requires GCC 13.0+ or Clang 16.0+, binutils 2.40+, and

	  zstd.



endchoice # "Compressed Debug information"



config DEBUG_INFO_SPLIT

	bool "Produce split debuginfo in .dwo files"

	depends on $(cc-option,-gsplit-dwarf)

scripts/Makefile.debug

+5 −1
Original line number Diff line number Diff line
@@ -27,10 +27,14 @@ else 
DEBUG_RUSTFLAGS	+= -Cdebuginfo=2

endif



ifdef CONFIG_DEBUG_INFO_COMPRESSED

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)