Messages in this thread | | | Date | Fri, 10 Dec 2021 09:28:36 -0700 | From | Nathan Chancellor <> | Subject | Re: [PATCH] Kconfig.debug: Make DEBUG_INFO selectable from a choice |
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On Thu, Dec 09, 2021 at 04:09:10PM -0800, Kees Cook wrote: > Currently it's not possible to enable DEBUG_INFO for an all*config > build, since it is marked as "depends on !COMPILE_TEST". This generally > makes sense because a debug build of an all*config target ends up taking > much longer and the output is much larger. Having this be "default off" > makes sense. However, there are cases where enabling DEBUG_INFO for such > builds is useful for doing treewide A/B comparisons of build options, > etc. > > Make DEBUG_INFO selectable from any of the DWARF version choice options, > with DEBUG_INFO_NONE being the default for COMPILE_TEST. The mutually > exclusive relationship between DWARF5 and BTF must be inverted, but the > result remains the same. Additionally moves DEBUG_KERNEL and DEBUG_MISC > up to the top of the menu because was enabling features _above_ it, > making it weird to navigate menuconfig. > > Suggested-by: Arnd Bergmann <arnd@arndb.de> > Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
> --- > lib/Kconfig.debug | 142 +++++++++++++++++++++++++--------------------- > 1 file changed, 76 insertions(+), 66 deletions(-) > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index 5c12bde10996..70ef47e92681 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -208,20 +208,89 @@ config DEBUG_BUGVERBOSE > > endmenu # "printk and dmesg options" > > +config DEBUG_KERNEL > + bool "Kernel debugging" > + help > + Say Y here if you are developing drivers or trying to debug and > + identify kernel problems. > + > +config DEBUG_MISC > + bool "Miscellaneous debug code" > + default DEBUG_KERNEL > + depends on DEBUG_KERNEL > + help > + Say Y here if you need to enable miscellaneous debug code that should > + be under a more specific debug option but isn't. > + > menu "Compile-time checks and compiler options" > > config DEBUG_INFO > - bool "Compile the kernel with debug info" > - depends on DEBUG_KERNEL && !COMPILE_TEST > + bool > help > - If you say Y here the resulting kernel image will include > - debugging info resulting in a larger kernel image. > + A kernel debug info option other than "None" has been selected > + in the "Debug information" choice below, indicating that debug > + information will be generated for build targets. > + > +choice > + prompt "Debug information" > + depends on DEBUG_KERNEL > + default DEBUG_INFO_NONE if COMPILE_TEST > + default DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT if DEBUG_KERNEL > + help > + Selecting something other than "None" results in a kernel image > + that will include debugging info resulting in a larger kernel image. > This adds debug symbols to the kernel and modules (gcc -g), and > is needed if you intend to use kernel crashdump or binary object > tools like crash, kgdb, LKCD, gdb, etc on the kernel. > - Say Y here only if you plan to debug the kernel. > > - If unsure, say N. > + Choose which version of DWARF debug info to emit. If unsure, > + select "Toolchain default". > + > +config DEBUG_INFO_NONE > + bool "Disable debug information" > + help > + Do not build the kernel with debugging information, which will > + result in a faster and smaller build. > + > +config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT > + bool "Rely on the toolchain's implicit default DWARF version" > + select DEBUG_INFO > + help > + The implicit default version of DWARF debug info produced by a > + toolchain changes over time. > + > + This can break consumers of the debug info that haven't upgraded to > + support newer revisions, and prevent testing newer versions, but > + those should be less common scenarios. > + > +config DEBUG_INFO_DWARF4 > + bool "Generate DWARF Version 4 debuginfo" > + select DEBUG_INFO > + help > + Generate DWARF v4 debug info. This requires gcc 4.5+ and gdb 7.0+. > + > + If you have consumers of DWARF debug info that are not ready for > + newer revisions of DWARF, you may wish to choose this or have your > + config select this. > + > +config DEBUG_INFO_DWARF5 > + bool "Generate DWARF Version 5 debuginfo" > + select DEBUG_INFO > + depends on !CC_IS_CLANG || (CC_IS_CLANG && (AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502))) > + help > + Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc > + 5.0+ accepts the -gdwarf-5 flag but only had partial support for some > + draft features until 7.0), and gdb 8.0+. > + > + Changes to the structure of debug info in Version 5 allow for around > + 15-18% savings in resulting image and debug info section sizes as > + compared to DWARF Version 4. DWARF Version 5 standardizes previous > + extensions such as accelerators for symbol indexing and the format > + for fission (.dwo/.dwp) files. Users may not want to select this > + config if they rely on tooling that has not yet been updated to > + support DWARF Version 5. > + > +endchoice # "Debug information" > > if DEBUG_INFO > > @@ -267,55 +336,11 @@ config DEBUG_INFO_SPLIT > to know about the .dwo files and include them. > Incompatible with older versions of ccache. > > -choice > - prompt "DWARF version" > - help > - Which version of DWARF debug info to emit. > - > -config DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT > - bool "Rely on the toolchain's implicit default DWARF version" > - help > - The implicit default version of DWARF debug info produced by a > - toolchain changes over time. > - > - This can break consumers of the debug info that haven't upgraded to > - support newer revisions, and prevent testing newer versions, but > - those should be less common scenarios. > - > - If unsure, say Y. > - > -config DEBUG_INFO_DWARF4 > - bool "Generate DWARF Version 4 debuginfo" > - help > - Generate DWARF v4 debug info. This requires gcc 4.5+ and gdb 7.0+. > - > - If you have consumers of DWARF debug info that are not ready for > - newer revisions of DWARF, you may wish to choose this or have your > - config select this. > - > -config DEBUG_INFO_DWARF5 > - bool "Generate DWARF Version 5 debuginfo" > - depends on !CC_IS_CLANG || (CC_IS_CLANG && (AS_IS_LLVM || (AS_IS_GNU && AS_VERSION >= 23502))) > - depends on !DEBUG_INFO_BTF > - help > - Generate DWARF v5 debug info. Requires binutils 2.35.2, gcc 5.0+ (gcc > - 5.0+ accepts the -gdwarf-5 flag but only had partial support for some > - draft features until 7.0), and gdb 8.0+. > - > - Changes to the structure of debug info in Version 5 allow for around > - 15-18% savings in resulting image and debug info section sizes as > - compared to DWARF Version 4. DWARF Version 5 standardizes previous > - extensions such as accelerators for symbol indexing and the format > - for fission (.dwo/.dwp) files. Users may not want to select this > - config if they rely on tooling that has not yet been updated to > - support DWARF Version 5. > - > -endchoice # "DWARF version" > - > config DEBUG_INFO_BTF > bool "Generate BTF typeinfo" > depends on !DEBUG_INFO_SPLIT && !DEBUG_INFO_REDUCED > depends on !GCC_PLUGIN_RANDSTRUCT || COMPILE_TEST > + depends on !DEBUG_INFO_DWARF5 > help > Generate deduplicated BTF type information from DWARF debug info. > Turning this on expects presence of pahole tool, which will convert > @@ -584,21 +609,6 @@ source "lib/Kconfig.kcsan" > > endmenu > > -config DEBUG_KERNEL > - bool "Kernel debugging" > - help > - Say Y here if you are developing drivers or trying to debug and > - identify kernel problems. > - > -config DEBUG_MISC > - bool "Miscellaneous debug code" > - default DEBUG_KERNEL > - depends on DEBUG_KERNEL > - help > - Say Y here if you need to enable miscellaneous debug code that should > - be under a more specific debug option but isn't. > - > - > menu "Memory Debugging" > > source "mm/Kconfig.debug" > -- > 2.30.2 >
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