On Fri, Aug 19, 2022 at 3:52 PM Dmitrii Bundin <dmitrii.bundin.a@xxxxxxxxx> wrote: > > On Fri, Aug 19, 2022 at 8:42 PM Nick Desaulniers > <ndesaulniers@xxxxxxxxxx> wrote: > > > > Is any of this really necessary? > > Consider the case if CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT=y. > Prior to GCC11/Clang12 -gsplit-dwarf implied -g2. So on newer > compilers with -gsplit-dwarf in use there would be no debug symbols > produced. ``` diff --git a/scripts/Makefile.debug b/scripts/Makefile.debug index 9f39b0130551..a881954c1382 100644 --- a/scripts/Makefile.debug +++ b/scripts/Makefile.debug @@ -1,7 +1,7 @@ DEBUG_CFLAGS := ifdef CONFIG_DEBUG_INFO_SPLIT -DEBUG_CFLAGS += -gsplit-dwarf +DEBUG_CFLAGS += -gsplit-dwarf -g2 else DEBUG_CFLAGS += -g endif ``` or perhaps that simply needs to be `-g -gsplit-dwarf`? In which case, that if/else could just be re-arranged. > -gdwarf-4/5 still implies -g2, but in case > CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT=y neither of the options are > set. -g is set, which has an implicit default level. > So it seems like a reasonable choice to provide a debug info > level config that would explicitly set the level without relying on > implicits. The default value of the config is set to -g2 to not change > the build behavior that was before introducing the option. And it > works for both older and newer versions of GCC/Clang in the same way. > The benefits of the -g1 option are indeed questionable except that it > produces an image with ~20% less in size. Until there's a concrete need, YAGNI. > > > It seems like a great way to bloat > > vmlinux artifacts built with CONFIG_DEBUG_INFO even further. > The defaults were chosen to not change the build behavior that was > before introducing the options. Or did you mean something else? > > > The > > above link mentions "when debugging with GDB." In that case, please > > don't add new Kconfigs for these; just set -g3 when > > CONFIG_GDB_SCRIPTS=y. > > CONFIG_GDB_SCRIPTS does not necessarily mean that -g3 is wanted, -g2 > (default) is usually a reasonable choice. The -g3 option is very > useful when debugging macro-intensive code, but requires much more > disk space to build. I documented it explicitly in the help section of > DEBUG_INFO_LEVEL. GCC and Clang use different options to include macro > definitions so it was handled depending on the compiler used. Honestly, I really don't think we need to be wrapping every compiler command line flag under the sun in a kconfig option. -- Thanks, ~Nick Desaulniers
