| Message ID | 1405466172-17055-2-git-send-email-andi@firstfloor.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Jul 16, 2014 at 01:16:12AM +0200, Andi Kleen wrote: > From: Andi Kleen <ak@linux.intel.com> > > I found that a lot of unresolvable variables when using gdb on the kernel > become resolvable when dwarf4 is enabled. So add a Kconfig flag to enable it. > > It definitely increases the debug information size, but on the other > hand this isn't so bad when debug fusion is used. Would it not make sense to try to enable degug info like this: First try -gdwarf-4 If this fails try -gdwarf-3 If this fails try -gdwarf-2 And if this also fails fallback to -g We could then us a Kconfig option to enable the highest debug level - where 4 for now is the highest. On the other hand if most people have revent utils then they all have -gdwarf-4 supported and then it is no big deal. Sam > > Signed-off-by: Andi Kleen <ak@linux.intel.com> > --- > Makefile | 3 +++ > lib/Kconfig.debug | 9 +++++++++ > 2 files changed, 12 insertions(+) > > diff --git a/Makefile b/Makefile > index 953659e..9c4080b 100644 > --- a/Makefile > +++ b/Makefile > @@ -690,6 +690,9 @@ KBUILD_CFLAGS += -g > KBUILD_AFLAGS += -Wa,-gdwarf-2 > endif > endif > +ifdef CONFIG_DEBUG_INFO_DWARF4 > +KBUILD_CFLAGS += -gdwarf-4 > +endif Should we sue $(call cc-option ...) here as not all gcc's supports this today? Sam -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Sun, Jul 20, 2014 at 09:23:15PM +0200, Sam Ravnborg wrote: > On Wed, Jul 16, 2014 at 01:16:12AM +0200, Andi Kleen wrote: > > From: Andi Kleen <ak@linux.intel.com> > > > > I found that a lot of unresolvable variables when using gdb on the kernel > > become resolvable when dwarf4 is enabled. So add a Kconfig flag to enable it. > > > > It definitely increases the debug information size, but on the other > > hand this isn't so bad when debug fusion is used. > > Would it not make sense to try to enable degug info like this: > First try -gdwarf-4 > If this fails try -gdwarf-3 > If this fails try -gdwarf-2 > And if this also fails fallback to -g > > We could then us a Kconfig option to enable the highest debug level - where 4 for now is the highest. > On the other hand if most people have revent utils then they all have -gdwarf-4 supported > and then it is no big deal. I made it a separate option, because dwarf4 is somewhat bigger than dwarf3 and it's probably only useful for people actively using gdb/crash (and I don't think others users like systemtap/perf probe do dwarf4 yet) If debug fusion was default it would be fine, but right now it would need converting a lot of debuginfo packaing scripts first. -Andi -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/Makefile b/Makefile index 953659e..9c4080b 100644 --- a/Makefile +++ b/Makefile @@ -690,6 +690,9 @@ KBUILD_CFLAGS += -g KBUILD_AFLAGS += -Wa,-gdwarf-2 endif endif +ifdef CONFIG_DEBUG_INFO_DWARF4 +KBUILD_CFLAGS += -gdwarf-4 +endif ifdef CONFIG_DEBUG_INFO_REDUCED KBUILD_CFLAGS += $(call cc-option, -femit-struct-debug-baseonly) \ diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index fb07c33..1af4d96 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -156,6 +156,15 @@ config DEBUG_INFO_SPLIT to know about the .dwo files and include them. Incompatible with older versions of ccache. +config DEBUG_INFO_DWARF4 + bool "Generate dwarf4 debuginfo" + depends on DEBUG_INFO + help + Generate dwarf4 debug info. This requires recent versions + of gcc and gdb. It makes the debug information larger. + But it significantly improves the success of resolving + variables in gdb on optimized code. + config ENABLE_WARN_DEPRECATED bool "Enable __deprecated logic" default y