2010-08-26 22:22:58 +04:00
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dnl #
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dnl # Check for libuuid
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dnl #
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AC_DEFUN([ZFS_AC_CONFIG_USER_LIBUUID], [
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LIBUUID=
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AC_CHECK_HEADER([uuid/uuid.h], [], [AC_MSG_FAILURE([
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*** uuid/uuid.h missing, libuuid-devel package required])])
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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
2016-03-15 20:28:07 +03:00
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AC_SEARCH_LIBS([uuid_generate], [uuid], [], [AC_MSG_FAILURE([
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2010-08-26 22:22:58 +04:00
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*** uuid_generate() missing, libuuid-devel package required])])
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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
2016-03-15 20:28:07 +03:00
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AC_SEARCH_LIBS([uuid_is_null], [uuid], [], [AC_MSG_FAILURE([
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2010-08-26 22:22:58 +04:00
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*** uuid_is_null() missing, libuuid-devel package required])])
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AC_SUBST([LIBUUID], ["-luuid"])
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AC_DEFINE([HAVE_LIBUUID], 1, [Define if you have libuuid])
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])
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