Re: [gentoo-dev] Defaulting for debug information in profiles

[Sven Eden]

Am Montag, 17. Dezember 2012, 11:48:12 schrieb Walter Dnes:
> On Mon, Dec 17, 2012 at 01:37:27PM +0100, Sven Eden wrote
>
> > 1) --- kde-base/kate
> > -----------------------------
> >
> > Compiled with -ggdb in CFLAGS:
> >  # sum=0; for file in $(equery f kde-base/kate | grep "\.debug") ; do
> >
> > xSize=$(stat -c "%s" $file) ; sum=$((sum+xSize)) ; done ; echo "$sum"
> > 32652140
> >
> > Compiled with -g in CFLAGS:
> >  # sum=0; for file in $(equery f kde-base/kate | grep "\.debug") ; do
> >
> > xSize=$(stat -c "%s" $file) ; sum=$((sum+xSize)) ; done ; echo "$sum"
> > 32652140
> >
> > Result: No size change at all.
> >
> >
> > 2) --- dev-libs/lzo
> > -----------------------------
> >
> > Compiled with -ggdb in CFLAGS:
> >  # sum=0; for file in $(equery f dev-libs/lzo | grep "\.debug") ; do
> >
> > xSize=$(stat -c "%s" $file) ; sum=$((sum+xSize)) ; done ; echo "$sum"
> > 558664
> >
> > Compiled with -g in CFLAGS:
> >  # sum=0; for file in $(equery f dev-libs/lzo | grep "\.debug") ; do
> >
> > xSize=$(stat -c "%s" $file) ; sum=$((sum+xSize)) ; done ; echo "$sum"
> > 558304
> >
> >
> > Result: A difference of 260 bytes or 0.06%. Far away from the assumed
> > 300%.
> >
> >
> > Conclusion:
> > I do not doubt that -ggdb adds size. It does. And maybe, if I did an
> > emerge -e @world would reduce the size used on my system between 30% and
> > 40%. But not about 66% like assumed.
> >
> >
> > However, even if it where "around 5-6" G, it would be thrice the initial
> > assumption of 2G. And that's the whole point.
>
>   On my 32-bit machines I have...
>
> FLAGS="-O2 -march=native -mfpmath=sse -fomit-frame-pointer -pipe
> -fno-unwind-tables -fno-asynchronous-unwind-tables" CXXFLAGS="${CFLAGS}"
>
>   See http://comments.gmane.org/gmane.linux.busybox/36695 for why I
> include "-fno-unwind-tables -fno-asynchronous-unwind-tables".  Would I
> have to rebuild system and world without...
>
> -fomit-frame-pointer -fno-unwind-tables -fno-asynchronous-unwind-tables
>
> ...to have debug data available?

No, you haven't, if you have compiled everything with "-g" or "-ggdb".

According to the web page you linked, the DWARF-2 tables are then written into 
the .debug files. Without -g/-ggdb, they are stripped and no longer available 
for debugging.

So according to your CFLAGS, you'd have to rebuild everything, yes, but a 
simple "-g" would do.

Oh, and "splitdebug" in "FEATURES" would be a good idea, too! ;)

Sincerly

Sven


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