Jim Cromie (jim.c...@gmail.com)

this thread reminds me that, many moons ago, I sent a patch
to teach Configure all the known config flags/options,
allowing it to complain/reject unknown options.

Im sure it doesnt apply anymore, and wasnt directly usable anyway,
as it patched the product of metaconfig, not the config-units.

It converted the large block of option definitions/initializations
into a here-doc, wrote the here-doc contents to an rc-file,
then dotted/sourced the rc-file into the shell running Configure.

A grep for each cmdline arg did the known-var check.

Any thoughts or interest ?

You seem to have grasped the general idea, if not the specifics,
I thought "it would be nice if"  installation (optionally) included 
extra steps to
extract debug-info to separate, strip installed exe.

I was under (evidently mistaken) impression that it was on a wish list
somewhere,
and I was curious enough..  Ill agree that it doesnt gain much 
(diskspace) unless done for a whole
distribution, doing just the local perl is not very useful.
> Separating out the debug info happens as basically the final
> step in building the executables. Instead of strip to eradicate
> all the debug info a smarter tool separates it out into a
> separate object file, then the debugger looks in known places and
> checks a checksum to verify it found the compatible debug info
> and puts it back together logically.
>
> Unless actually doing rpm packaging is part of Configure, I
> don't know what there might be for Configure to do.
>
> Side note: on debian/ubuntu, the "separate debug info" is much
> stranger. The separate files gdb can find in the debug-file-directory
> tend to only have the linker symbols that were stripped out
> and there is no debug info at all. Meanwhile, up at the root
> of the debug-file-directory there is a complete separate copy
> of the whole object file with dwarf included, but gdb can't find
> it automatically. I have no idea what they were thinking in
> debian world :-).
>
> (I've done all the work to support this in the NightView debugger
> from Concurrent - www.ccur.com, so I'm somewhat familiar with
> all this nonsense).
>
>
>   

thanks for adding that info - I faound it interesting (and, well, its
all about me ;-)

oops.  I should have scanned more carefully.
apologies to everyone who gets one of these, elsewhere too.

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I recall seeing this somewhere (maybe perltodo..)

while doing a bit of surface-scratching, I pasted these notes together,
I think theyre enough to get the curious going, maybe further.

In my mind, the biggest questions are around how to integrate it
into Configure, hints, etc, and how general to try to make it.
Presumably, gcc & gdb are nearly ubuiquitous on *nix platforms,

I run fedora 8, and they have reduces this stuff to practice,
so Ive ccd Tom "spot" Callaway. and invite others to offer comments.


anyway heres the notes:


http://rephil.ca/cgi-bin/info2www?(/usr/share/info/gdb.info.gz)Separate+Debug+Files


gdb
`show debug-file-directory'
     Show the directory GDB searches for separate debugging information
     files.

(gdb) show debug-file-directory
The directory where separate debug symbols are searched for is
"/usr/lib/debug".
(gdb) q

on my fedora box, the system perl includes these pertinent items,
but there is no /usr/lib/debug directory,

readelf -a /usr/bin/perl (trimmed)

  [ 3] .note.gnu.build-i NOTE            08048168 000168 000024 00   A  
0   0  4
  [28] .gnu_debuglink    PROGBITS        00000000 002f84 000014 00      
0   0  4

readelf -x3 -x28 /usr/bin/perl

Hex dump of section '.note.gnu.build-id':
  0x08048168 04000000 14000000 03000000 474e5500 ............GNU.
  0x08048178 f058de72 15e0fddd 5485c538 75bc54c9 .X.r....T..8u.T.
  0x08048188 42f72597                            B.%.

Hex dump of section '.gnu_debuglink':
  0x00000000 7065726c 352e382e 382e6465 62756700 perl5.8.8.debug.
  0x00000010 a74a6798                            .Jg.


  GNU binary utilities (Binutils) package includes the `objcopy'
utility that can produce the separated executable / debugging
information file pairs using the following commands:

     objcopy --only-keep-debug perl.gcov gcov.debug
     strip -g foo

add info to stripped perl
     objcopy --add-gnu-debuglink=gcov.debug perl.gcov

I believe the above changed the gdb 'run' response to *stop* showing
5-6 lines of "no symbols found" (

parts of a try script, to feed to gdb

[[email protected: j...@harpo] gcov]$ gdb -q --args perl.stripped -e 1
Using host libthread_db library "/lib/libthread_db.so.1".
(gdb) r
Starting program: /home/jimc/perl/core/dev/gcov.old/perl.stripped -e 1
[Thread debugging using libthread_db enabled]

Program exited normally.
Missing separate debuginfos, use: debuginfo-install glibc.i686