svn commit: r211561 - head/cddl/lib/drti

[Kostik Belousov]

On Sat, Aug 21, 2010 at 03:33:35PM +0100, Rui Paulo wrote:
> 
> On 21 Aug 2010, at 15:23, Kostik Belousov wrote:
> 
> > On Sat, Aug 21, 2010 at 03:16:49PM +0100, Rui Paulo wrote:
> >> 
> >> On 21 Aug 2010, at 14:59, Kostik Belousov wrote:
> >> 
> >>> On Sat, Aug 21, 2010 at 01:48:05PM +0000, Rui Paulo wrote:
> >>>> Author: rpaulo
> >>>> Date: Sat Aug 21 13:48:04 2010
> >>>> New Revision: 211561
> >>>> URL: http://svn.freebsd.org/changeset/base/211561
> >>>> 
> >>>> Log:
> >>>> Link drti.o with a PIC version of libelf. This is needed because
> >>>> drti.o depends on libelf and this avoids linking every other drti.o
> >>>> program (namely programs with USDT probes) with libelf.
> >>> What is wrong with having libelf as dependency of the resulting
> >>> binary ?
> >> 
> >> The resulting binary can be a library. If I add drti.o to the libthr
> >> library, every other program will break because it can't find libelf
> >> symbols. The only way to fix it would be to rebuild every program that
> >> depends on libthr and I don't want that to happen.
> > 
> > I do not understand this. If drti.o is added to a library, library should
> > also record a dependency on libelf, i.e. be linked with it. Since you
> > already modifying link command to add drti.o, what is the problem to
> > add -lelf ?
> 
> I wanted the same steps to be done in FreeBSD as in Solaris. I.e., in
> I Solaris you don't need to link with -lelf your program after you
> I added DTrace probes to it believe this is a good tradeoff          .

The drawbacks of linking library statically are, at least:
- Wasted space.
- Harder upgrade when libelf changes. Much harder for ports and hand-
  compiled programs.
- The mess that happen when the binary also linked with -lelf, and
  either your drti.o is linked, or a library that linked with its
  dcrti.o.
Pro argument seems to be that one less diff with Solaris code is needed.

This is becoming rather long.
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