Richard Yao e853ba3519 Cleanup linking ... I noticed during code review of zfsonlinux/zfs#4385 that the author of a commit had peppered the various Makefile.am files with `$(TIRPC_LIBS)` when putting it into `lib/libspl/Makefile.am` should have sufficed. Upon further examination, it seems that he had copied what we do with `$(ZLIB)`. We also have a bit of that with `-ldl` too. Unfortunately, what we do is wrong, so lets fix it to set a good example for future contributors. In addition, we have multiple `-lz` and `-luuid` passed to the compiler because each `AC_CHECK_LIB` adds it to `$LIBS`. That is somewhat annoying to see, so we switch to `AC_SEARCH_LIBS` to avoid it. This is consistent with the recommendation to use `AC_SEARCH_LIBS` over `AC_CHECK_LIB` by autotools upstream: https://www.gnu.org/software/autoconf/manual/autoconf-2.66/html_node/Libraries.html In an ideal world, this would translate into improvements in ELF's `DT_NEEDED` entries, but that is not the case because of a couple of bugs in libtool. The first bug causes libtool to overlink by using static link dependencies for dynamic linking: https://wiki.mageia.org/en/Overlinking_issues_in_packaging#libtool_issues The workaround for this should be to pass `-Wl,--as-needed` in `LDFLAGS`. That leads us to the second bug, where libtool passes `LDFLAGS` after the libraries are specified and `ld` will only honor `--as-needed` on libraries specified before it: https://sigquit.wordpress.com/2011/02/16/why-asneeded-doesnt-work-as-expected-for-your-libraries-on-your-autotools-project/ There are a few possible workarounds for the second bug. One is to either patch the compiler spec file to specify `-Wl,--as-needed` or pass `-Wl,--as-needed` via `CC` like `CC='gcc -Wl,--as-needed'` so that it is specified early. Another is to patch ltmain.sh like Gentoo does: https://gitweb.gentoo.org/repo/gentoo.git/tree/eclass/ELT-patches/as-needed Without one of those workarounds, this cleanup provides no benefit in terms of `DT_NEEDED` entry generation. It should still be an improvement because it nicely simplifies the code while encouraging good habits when patching autotools scripts. Signed-off-by: Richard Yao <ryao@gentoo.org> Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #4426		2016-03-18 13:31:11 -07:00
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.gitignore	Add .gitignore files to exclude build products	2010-01-08 11:35:17 -08:00
Makefile.am	Cleanup linking	2016-03-18 13:31:11 -07:00
zdb_il.c	Fix for recent zdb -h | -i crashes (seg fault)	2015-06-26 14:14:31 -07:00
zdb.c	Correctly parse -R flag arguments	2016-02-05 11:29:38 -08:00