9f8fe64779
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>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.