Re: [gentoo-dev] Re: Split ELF Debug (default or not?)

[Ned Ludd <solar@gentoo.org>]

On Sun, 2005-11-27 at 15:09 +0200, Ivan Yosifov wrote:
> On Sun, 2005-11-27 at 07:24 -0500, Ned Ludd wrote:
> > On Sat, 2005-11-26 at 13:20 -0600, R Hill wrote:
> > > Ned Ludd wrote:
> > > > Good afternoon,
> > > > 
> > > > probably in portage-2.0.54 a patch will be added to emit split debug
> > > > info. Having a split debug allows us to retain all the advantages of
> > > > stripping executables while gaining the ability to properly debug
> > > > executables in bfd aware programs. It's been in testing with a small
> > > > hand full of devs and works quite well, but before it's pushed in we
> > > > would like to get input from our devs & users.
> > > > 
> > > > Would you be willing to give up space in $ROOT/usr/lib/debug for ELF
> > > > executables by default in order to aid in better debugging by or do we
> > > > want to only emit it when a FEATURE= is defined.
> > > 
> > > How much space are we talking about?
> > 
> > There is no fixed size here and depends on the number of packages you 
> > have and the CFLAGS passed to the programs you build. 
> > Naturally if you start building all your code with 
> > CFLAGS="-g3 -ggdb" your going to end up with a larger debug info.
> 
> Of course I will be compiling with CFLAGS="-g3 -ggdb" :)
> 
> The reason I don't do it now is because debug info:
> 
> 1) makes binaries larger
> 2) makes binaries slower ( in my experience ( may have to do with 1) )
> 
> And I don't ( not sure if anyone does ) care about any non-gdb debugger.
> 
> So, can you give us a wild guess about the disk space ? How much does it
> take on your system and how many packages do you have installed ?

-rwxr-xr-x  1 root root 49268 Nov 19 18:00 /usr/bin/scanelf
-rw-r--r--  1 root root  5292 Nov 19
18:02 /usr/lib/debug/usr/bin/scanelf.debug


I really can't give an accurate example. Halcyon who has been testing it
merged world and he was yeilded with 18M of debug info (I have no idea
how many packages he has). ChrisWhite has also been merging a lot of
merging with it recently to test KDE stuff which is a pretty big
package. He may have some useful data that your after. The reason I
posted the patch and prepstrip here was so that people could formulate
their own opinions.

I'm also using an additional patch in my local portage system where I'm 
sub packaging the debug info and it only gets installed when I tell it 
to be installed via the emerge -K option. I use some pretty crafty 
tricks to accomplish this like dynamic ebuild creation. I do this in
order to have compressed debug info handy vs having it on the live
filesystem. This probably would not be accepted by portage mainline 
unless I do it in a more elegant way that wont conflict with the future 
portage-3.x series.

> And one more thing. For proper debugging, don't I need the source to be
> present ?

-g3 -ggdb embeds the source code in the debug info so I don't see the 
point.

-- 
Ned Ludd <solar@gentoo.org>
Gentoo Linux

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