Thanks for the clear explanation of *.a and *.so files, Stas. I'm starting to grok how it works together.
I've attached the diff to the install docs to this message which incorporates some of your notes about .so and .a files. I found this information hard to find while browsing Google, Perlmonks and the modperl docs. I hope that you will include them in some form. Thanks, William -- Knowmad Services Inc. http://www.knowmad.com
--- /tmp/install.pod.orig 2004-12-31 10:04:39.000000000 -0500 +++ /tmp/install.pod.wlm 2004-12-31 11:58:30.000000000 -0500 @@ -681,9 +681,38 @@ mod_perl.o(.text+0x13b): undefined reference to `Perl_av_undef' [more errors snipped] -This happens when you have Perl built statically linked, with no -shared I<libperl.a>. Build a dynamically linked Perl (with -I<libperl.a>) and the problem will disappear. +This happens when you have perl built statically linked, with no +shared I<libperl.so> library. Build a dynamically linked perl (with +I<libperl.so>) and the problem will disappear. See the "Building a shared Perl +library" section from the I<INSTALL> file that comes with Perl sources. Also +see L<"Chapter 15.4 - Perl Build +Options"|http://modperlbook.org/html/ch15_04.html> from I<Practical mod_perl>. + +=head4 Further notes on libperl.(a|so) + +Library files such as I<libfoo.a> are archives that are used at linking time - +these files are completely included in the final application that linked it. + +I<libfoo.so> is a shared library. At the linking time the application only +knows which library it wants. Only at the loading time (runtime) that +library will be loaded. + +One of the benefits of using a shared library, is that it's loaded only once, +any application using the same library will not need load it, it'll be shared +(a service provided by the kernel). In the case of static I<libfoo.a>, it'll be +loaded as many times as there are applications that included it, thus consuming +more memory. Of course this is not the only benefit of using shared libs. + +In mod_perl1, the library file is unfortunately named libperl.(so|a). So you +have libperl.(so|a) which is perl, and you have libperl.(so|a) which is +modperl. You are certainly looking at the modperl version of libperl.a if you +find it in the apache directory. perl's libperl.(so|a) lives under something +like 5.8.6/i686-linux/CORE/. + +Some distributions (notably Debian) have chosen to put libperl.so into the +library path (e.g., /usr/lib) which will cause linking problems when compiling +mod_perl. You should delete or move aside the libperl.so while building +mod_perl or else will likely encounter further errors. =head2 mod_perl Building (make)
-- Report problems: http://perl.apache.org/bugs/ Mail list info: http://perl.apache.org/maillist/modperl.html List etiquette: http://perl.apache.org/maillist/email-etiquette.html
