On Mon, Nov 7, 2022 at 7:08 PM Nick Desaulniers <ndesaulniers@xxxxxxxxxx> wrote: > > Make DEBUG_INFO_COMPRESSED a choice; DEBUG_INFO_UNCOMPRESSED is the > default, DEBUG_INFO_COMPRESSED uses zlib, DEBUG_INFO_COMPRESSED_ZSTD > uses zstd. > > 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_UNCOMPRESSED=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=y (zlib): > 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 (zstd): > 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. > > This renames the existing KConfig options: > * DEBUG_INFO_UNCOMPRESSED -> DEBUG_INFO_COMPRESSED_NONE > * DEBUG_INFO_COMPRESSED -> DEBUG_INFO_COMPRESSED_ZLIB > So users upgrading may need to reset the new Kconfigs. > > 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@xxxxxxx> > Reviewed-by: Nathan Chancellor <nathan@xxxxxxxxxx> > Signed-off-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx> > --- > Changes v1 -> v2: > * Remove `depends on DEBUG_KERNEL` as per Nathan. > * Rename Kconfigs as per Sedat and Masahiro. > * Add note about renamed Kconfigs to commit message. > * Add more help text to DEBUG_INFO_COMPRESSED_ZSTD. > > lib/Kconfig.debug | 29 +++++++++++++++++++++++++++-- > scripts/Makefile.debug | 4 ++++ > 2 files changed, 31 insertions(+), 2 deletions(-) > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index 29280072dc0e..7c28a8fba02e 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -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) > diff --git a/scripts/Makefile.debug b/scripts/Makefile.debug > index 332c486f705f..8ac3379d2255 100644 > --- a/scripts/Makefile.debug > +++ b/scripts/Makefile.debug > @@ -31,6 +31,10 @@ ifdef CONFIG_DEBUG_INFO_COMPRESSED ^^ ifdef CONFIG_DEBUG_INFO_COMPRESSED_ZLIB ...from a quick (re)view. -Sedat- > 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) > > base-commit: f0c4d9fc9cc9462659728d168387191387e903cc > -- > 2.38.1.431.g37b22c650d-goog >
