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As debug information gets larger and larger, it helps significantly save
the size of vmlinux images to compress the information in the debug
information sections. Note: this debug info is typically split off from
the final compressed kernel image, which is why vmlinux is what's used
in conjunction with GDB. Minimizing the debug info size should have no
impact on boot times, or final compressed kernel image size.
All of the debug sections will have a `C` flag set.
$ readelf -S <object file>
$ bloaty vmlinux.gcc75.compressed.dwarf4 -- \
vmlinux.gcc75.uncompressed.dwarf4
FILE SIZE VM SIZE
-------------- --------------
+0.0% +18 [ = ] 0 [Unmapped]
-73.3% -114Ki [ = ] 0 .debug_aranges
-76.2% -2.01Mi [ = ] 0 .debug_frame
-73.6% -2.89Mi [ = ] 0 .debug_str
-80.7% -4.66Mi [ = ] 0 .debug_abbrev
-82.9% -4.88Mi [ = ] 0 .debug_ranges
-70.5% -9.04Mi [ = ] 0 .debug_line
-79.3% -10.9Mi [ = ] 0 .debug_loc
-39.5% -88.6Mi [ = ] 0 .debug_info
-18.2% -123Mi [ = ] 0 TOTAL
$ bloaty vmlinux.clang11.compressed.dwarf4 -- \
vmlinux.clang11.uncompressed.dwarf4
FILE SIZE VM SIZE
-------------- --------------
+0.0% +23 [ = ] 0 [Unmapped]
-65.6% -871 [ = ] 0 .debug_aranges
-77.4% -1.84Mi [ = ] 0 .debug_frame
-82.9% -2.33Mi [ = ] 0 .debug_abbrev
-73.1% -2.43Mi [ = ] 0 .debug_str
-84.8% -3.07Mi [ = ] 0 .debug_ranges
-65.9% -8.62Mi [ = ] 0 .debug_line
-86.2% -40.0Mi [ = ] 0 .debug_loc
-42.0% -64.1Mi [ = ] 0 .debug_info
-22.1% -122Mi [ = ] 0 TOTAL
For x86_64 defconfig + LLVM=1 (before):
Elapsed (wall clock) time (h:mm:ss or m:ss): 3:22.03
Maximum resident set size (kbytes): 43856
For x86_64 defconfig + LLVM=1 (after):
Elapsed (wall clock) time (h:mm:ss or m:ss): 3:32.52
Maximum resident set size (kbytes): 1566776
Thanks to:
Nick Clifton helped us to provide the minimal binutils version.
Sedat Dilek found an increase in size of debug .deb package.
Cc: Nick Clifton <nickc@redhat.com>
Suggested-by: David Blaikie <blaikie@google.com>
Reviewed-by: Fangrui Song <maskray@google.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
|
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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.