Re: openmotif and libXp.a (xemacs-21.2)

Darryl> Martin Buchholz <martin(a)xemacs.org&gt; wrote: Darryl> Yes, but your copy of OpenMotif references libXp -- see below. Darryl> You have it backwards (or maybe I'm misunderstanding your Darryl> english). There are new (?) Motif print routines in OpenMotif, and Darryl> these routines call functions in the X print library (libXp). Darryl> ^^^^^^^^^^ Darryl> Huh? This looks like libXp to me. OOOOPS! I stand corrected. Refuted by my own evidence! OK, I thought libXp was part of OpenMotif, but no, it's merely *used* by OpenMotif. libXp is part of X11R6. Darryl> Hmmm. I'm not very familiar with Linux. Does Linux have some kind Darryl> of deferred linking, where symbols in shared libraries are not resolved Darryl> at link time but at runtime, instead? Darryl> [ Oh. Ah. If I recall correctly, FreeBSD 3.X (which Kasahara-san is Darryl> using), did not have deferred linking; all symbols in all libraries Darryl> had to be resolved (must exist and be found) at link time. FreeBSD Darryl> 4.X (and probably Linux) use deferred linking, where symbols in shared Darryl> libraries aren't checked and resolved until runtime (this means that Darryl> unresolved symbols like XpStartPage would cause a core dump at runtime Darryl> if the symbol could not be found). This is probably what you're Darryl> seeing. I'd bet that your XEmacs would dump core if it tried to Darryl> reference a Motif print function (which references libXp, which Darryl> doesn't exist on your system). This probably means that someone Darryl> (you?) will have to change configure to check for libXp on those Darryl> systems for which deferred linking is not used. ] Darryl> [ P.S. -- I'm not sure if the correct term is really "deferred linking", Darryl> but that's what I've been calling it. ] (martin＠lasker) ~/src $ gcc xm.c /tmp/cc03owBq.o: In function `main': /tmp/cc03owBq.o(.text+0xc): undefined reference to `XmStringFree' (martin＠lasker) ~/src $ gcc xm.c -L /usr/local/dt/lib -lXm (martin＠lasker) ~/src $ cat xm.c int main (int argc, char *argv[]) { XmStringFree(); } Look at the above. This is the correct way for the system to behave, I believe. If app xx uses a symbol from library ll, then xx should only need to link with ll. If ll in turn needs some other library mm, then that should be transparent to xx, and taken care of at the time that ll is built. Despite my major gaffe above, I believe my point is still valid. Note that libXm.so's dependencies are recorded in the libXm.so file. So when a user links with libXm.so, the linker is smart enough to (recursively) link in libXp.so from elsewhere. If the BSD linker is so stupid that it is impossible to use -lXm without also specifying -lXp, then BSD as a whole is horribly broken. But I don't believe that. Here is some documentation from GNU ld, apparently used by freebsd: `-rpath-link DIR' When using ELF or SunOS, one shared library may require another. This happens when an `ld -shared' link includes a shared library as one of the input files. When the linker encounters such a dependency when doing a non-shared, non-relocateable link, it will automatically try to locate the required shared library and include it in the link, if it is not included explicitly. In such a case, the `-rpath-link' option specifies the first set of directories to search. The `-rpath-link' option may specify a sequence of directory names either by specifying a list of names separated by colons, or by appearing multiple times. The linker uses the following search paths to locate required shared libraries. 1. Any directories specified by `-rpath-link' options. 2. Any directories specified by `-rpath' options. The difference between `-rpath' and `-rpath-link' is that directories specified by `-rpath' options are included in the executable and used at runtime, whereas the `-rpath-link' option is only effective at link time. 3. On an ELF system, if the `-rpath' and `rpath-link' options were not used, search the contents of the environment variable `LD_RUN_PATH'. 4. On SunOS, if the `-rpath' option was not used, search any directories specified using `-L' options. 5. For a native linker, the contents of the environment variable `LD_LIBRARY_PATH'. 6. The default directories, normally `/lib' and `/usr/lib'. If the required shared library is not found, the linker will issue a warning and continue with the link. Martin