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developingpld:advanceddeveloping:fixingasneeded [2006-08-07 02:41] SamChi - some fixes |
developingpld:advanceddeveloping:fixingasneeded [2006-08-07 21:05] SamChi |
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===== How --as-needed works ===== | ===== How --as-needed works ===== | ||
- | With ''--as-needed'' enabled only libraries which contain symbols required by __object files__ are linked. | + | With ''--as-needed'' enabled, only libraries containing symbols required by __object files__ are linked. |
== About positions == | == About positions == | ||
- | Linker options are positional, and position is very important. Because it looks for missing symbols only in libraries coming after object file. | + | Linker options are positional, and position is very important. It looks for missing symbols only in libraries coming after object file. |
- | Correct ones are: | + | Correct positions are: |
<file>$ gcc $(LDFLAGS) -o $@ $(OBJECTS) $(LIBS) | <file>$ gcc $(LDFLAGS) -o $@ $(OBJECTS) $(LIBS) | ||
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and this generally works well. | and this generally works well. | ||
- | If there is something like that: | + | |
+ | If there is something like that: | ||
<file>$ gcc -Wl,--as-needed -l<library> <objects.o> | <file>$ gcc -Wl,--as-needed -l<library> <objects.o> | ||
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the library will __never__ be linked, because it's not required at the time it's checked. | the library will __never__ be linked, because it's not required at the time it's checked. | ||
- | And with something like that: | + | |
+ | And with something like that: | ||
<file>$ gcc -l<library> -Wl,--as-needed <objects.o> | <file>$ gcc -l<library> -Wl,--as-needed <objects.o> | ||
Line 44: | Line 46: | ||
==== Short examples ==== | ==== Short examples ==== | ||
- | Most of problems are with readline/ncurses and tinfo, and it's nice example: tinfo is required by both readline and ncurses, and both are linked with this library (now, when I've [[http://cvs.pld-linux.org/cgi-bin/cvsweb/SOURCES/readline-shared.patch?r1=1.6&r2=1.7|fixed readline]];). | + | Most of problems are with readline/ncurses and tinfo, and it's nice example: tinfo is required by both readline and ncurses, and both are linked with this library (now, when I've [[http://cvs.pld-linux.org/cgi-bin/cvsweb/SOURCES/readline-shared.patch?r1=1.6&r2=1.7|fixed readline]]). |
- | But some packages link with readline or ncurses while they use __only__ symbols from tinfo. //Without// ''--as-needed'' those executables work because they are linked with tinfo from readline/ncurses library. //With// ''--as-needed'' it will not work, because readline/ncurses contain no symbols required by executable so they are not linked, it's dependencies naturally are neither linked. Thats why there is a need to pass ''-ltinfo''. If it requires only symbols from tinfo it's ok to ''s/ncurses/tinfo/''. But if it really requires readline/ncurses but there is some executable (or ./configure) which requires only tinfo both ''-lreadline''/''-lncurses'' and ''-ltinfo'' should be passed. | + | But some packages link with readline or ncurses while they use __only__ symbols from tinfo. //Without// ''--as-needed'' those executables work because they are linked with tinfo from readline/ncurses library. //With// ''--as-needed'' it will not work, because readline/ncurses contain no symbols required by executable so they are not linked, it's dependencies naturally are neither linked. Thats why there is a need to pass ''-ltinfo''. If it requires only symbols from tinfo it's ok to ''s/ncurses/tinfo/''. But if it really requires readline/ncurses but there is some executable (or ./configure) which requires only tinfo both ''-lreadline''/''-lncurses'' and ''-ltinfo'' should be passed. |
For a longer example take a look at real example nr. 1. | For a longer example take a look at real example nr. 1. | ||
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<file>$ gcc -Wl,--as-needed -o executable <objects.o> -l2 -l1 | <file>$ gcc -Wl,--as-needed -o executable <objects.o> -l2 -l1 | ||
</file> | </file> | ||
- | it's usual when object files require only library 2, and -l1 is required by -l2. As I said linker only checks for symbols from objects, so -l1 is not linked. Normally it is easy to fix it, simply make sure while linking -l2 it is linked to -l1 (take a look at the second real example). | + | It's usual situation when object files require only library 2, and //-l1// is required by //-l2//. As I said linker only checks for symbols from objects, so //-l1// is not linked. Normally it is easy to fix it, simply make sure while linking //-l2// it is linked to //-l1// (take a look at the second real example). |
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- | <file>x86_64-pld-linux-g++ -DNOMMGR -Wall -DGAMEDATADIR=\"/usr/share/xmoto\" -ggdb -O2 -Wl,--as-needed -o xmoto-edit BuiltInFont.o [...object files...] Packager.o -lGL -lcurl -lode -llualib50 -llua50 -lSDL_mixer -lbz2 -lz -lpng -ljpeg | + | <file>x86_64-pld-linux-g++ -Wl,--as-needed -o xmoto-edit BuiltInFont.o [...object files...] Packager.o -lGL -lcurl -lode -llualib50 -llua50 -lSDL_mixer -lbz2 -lz -lpng -ljpeg |
VApp.o: In function `vapp::App::getRealTime()': | VApp.o: In function `vapp::App::getRealTime()': | ||
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Binary file /usr/lib64/libSDL.so matches | Binary file /usr/lib64/libSDL.so matches | ||
</file> | </file> | ||
- | they are in ''-lSDL'', but binary does not link with ''-lSDL''; edit Makefile by hand and add ''-lSDL'' at the same place ''-lSDL_mixer'' is: ''LIBS = -lcurl -lode -llualib50 -llua50 -lSDL_mixer -lSDL -lbz2 -lz -lpng -ljpeg'' | + | They are in ''-lSDL'', but binary does not link with ''-lSDL''. Edit Makefile by hand and add ''-lSDL'' at the same place ''-lSDL_mixer'' is: ''LIBS = -lcurl -lode -llualib50 -llua50 -lSDL_mixer -lSDL -lbz2 -lz -lpng -ljpeg'' |
What we get after running make in build tree: | What we get after running make in build tree: | ||
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- | <file>x86_64-pld-linux-g++ -DNOMMGR -Wall -DGAMEDATADIR=\"/usr/share/xmoto\" -ggdb -O2 -Wl,--as-needed -o xmoto-edit BuiltInFont.o [...object files...] Packager.o -lcurl -lode -llualib50 -llua50 -lSDL_mixer -lSDL -lbz2 -lz -lpng -ljpeg | + | <file>x86_64-pld-linux-g++ -Wl,--as-needed -o xmoto-edit BuiltInFont.o [...object files...] Packager.o -lcurl -lode -llualib50 -llua50 -lSDL_mixer -lSDL -lbz2 -lz -lpng -ljpeg |
VApp.o: In function `vapp::App::grabScreen()': | VApp.o: In function `vapp::App::grabScreen()': | ||
Line 137: | Line 139: | ||
- | <file>x86_64-pld-linux-g++ -DNOMMGR -Wall -DGAMEDATADIR=\"/usr/share/xmoto\" -mfpmath=sse -ggdb -O2 -ftree-vectorize -ftree-vectorizer-verbose=1 -march=athlon64 -mmmx -msse -msse2 -m3dnow -s -Wl,--as-needed -Wl,-s -o xmoto-edit BuiltInFont.o Image.o LevelSrc.o VApp.o VBezier.o VDraw.o VDrawText.o VFileIO.o VMath.o VTexture.o VXml.o tim.o tim_io_stdio.o tim_jpeg.o tim_memory_crt.o tim_png.o tinystr.o tinyxml.o tinyxmlerror.o tinyxmlparser.o md5.o md5file.o FileCompression.o SwapEndian.o DBuffer.o CRCHash.o Theme.o WWW.o Editor.o EditorMain.o EditorData.o EditorLog.o Packager.o -lcurl -lode -llualib50 -llua50 -lSDL_mixer -lSDL -lGL -lbz2 -lz -lpng -ljpeg | + | <file>x86_64-pld-linux-g++ -Wl,--as-needed -o xmoto-edit BuiltInFont.o [...object files...] Packager.o -lcurl -lode -llualib50 -llua50 -lSDL_mixer -lSDL -lGL -lbz2 -lz -lpng -ljpeg |
make[1]: Leaving directory `/home/users/sparky/rpm/BUILD/xmoto-0.2.0' | make[1]: Leaving directory `/home/users/sparky/rpm/BUILD/xmoto-0.2.0' | ||
</file> | </file> | ||
- | //It worked !// | + | **It worked !** |
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- | <file>/bin/sh ../libtool --tag=CC --mode=link x86_64-pld-linux-gcc -ggdb -O2 -Wall -Wmissing-prototypes -Wno-sign-compare -Wl,--as-needed -o test-source-selector test-source-selector.o libedataserverui-1.2.la ../libedataserver/libedataserver-1.2.la -pthread -lglade-2.0 -lgtk-x11-2.0 -lxml2 -lgdk-x11-2.0 -latk-1.0 -lgdk_pixbuf-2.0 -lpangocairo-1.0 -lXext -lXrender -lXinerama -lXi -lXrandr -lXcursor -lXfixes -lcairo -lpangoft2-1.0 -lfontconfig -lfreetype -lz -lpango-1.0 -lX11 -lgnome-2 -lpopt -lbonobo-2 -lgnomevfs-2 -lbonobo-activation -lgconf-2 -lgobject-2.0 -lORBit-2 -lm -lgmodule-2.0 -ldl -lgthread-2.0 -lgnome-keyring -lglib-2.0 -lpthread | + | <file>/bin/sh ../libtool --tag=CC --mode=link x86_64-pld-linux-gcc -Wl,--as-needed -o test-source-selector test-source-selector.o libedataserverui-1.2.la ../libedataserver/libedataserver-1.2.la -pthread -lglade-2.0 [...many -l libraries...] |
+ | -lgnome-keyring -lpthread | ||
- | x86_64-pld-linux-gcc -ggdb -O2 -ftree-vectorize -ftree-vectorizer-verbose=1 -march=athlon64 -mmmx -msse -msse2 -m3dnow -mfpmath=sse -Wall -Wmissing-prototypes -Wno-sign-compare -Wl,--as-needed -o .libs/test-source-selector test-source-selector.o -pthread ./.libs/libedataserverui-1.2.so [many, many .so and -l libraries] -lpthread | + | x86_64-pld-linux-gcc -Wl,--as-needed -o .libs/test-source-selector test-source-selector.o -pthread ./.libs/libedataserverui-1.2.so [...many, many .so and -l libraries...] -lpthread |
./.libs/libedataserverui-1.2.so: undefined reference to `glade_xml_new' | ./.libs/libedataserverui-1.2.so: undefined reference to `glade_xml_new' | ||
Line 209: | Line 212: | ||
''GNOME_KEYRING_LIBS = -lgnome-keyring -lglib-2.0'' | ''GNOME_KEYRING_LIBS = -lgnome-keyring -lglib-2.0'' | ||
- | So add this one and glade to that library deps: | + | So add this one and ''-lglade-2.0'' to that library deps: |
Line 232: | Line 235: | ||
== Why was it working without --as-needed ? == | == Why was it working without --as-needed ? == | ||
- | test-source-selector binary was linked with all libraries needed by libedataserverui-1.2.so, and the binary was the one who provided missing symbols to libedataserverui-1.2.so | + | ''test-source-selector'' binary was linked with all libraries needed by libedataserverui-1.2.so, and the binary was the one who provided missing symbols to libedataserverui-1.2.so |
+ | |||
+ | |||
+ | |||
+ | === What if broken library comes from other package ? === | ||
+ | You can check manually does library has all required symbols, simply running ' gcc //library// ', like this: | ||
+ | |||
+ | This is an example of correctly linked library: | ||
+ | |||
+ | <file>$ gcc /usr/lib64/liblftp-tasks.so.0.0.0 | ||
+ | /usr/lib64/gcc/x86_64-pld-linux/4.1.2/../../../../lib64/crt1.o: In function `_start': | ||
+ | (.text+0x20): undefined reference to `main' | ||
+ | collect2: ld returned 1 exit status | ||
+ | </file> | ||
+ | And inclorrectly linked one: | ||
+ | |||
+ | <file>$ gcc /usr/lib64/liblftp-jobs.so.0.0.0 | ||
+ | /usr/lib64/gcc/x86_64-pld-linux/4.1.2/../../../../lib64/crt1.o: In function `_start': | ||
+ | (.text+0x20): undefined reference to `main' | ||
+ | /usr/lib64/liblftp-jobs.so.0.0.0: undefined reference to `StringSet::Remove(int)' | ||
+ | /usr/lib64/liblftp-jobs.so.0.0.0: undefined reference to `Buffer::Format(char const*, ...)' | ||
+ | [...] | ||
+ | /usr/lib64/liblftp-jobs.so.0.0.0: undefined reference to `SMTask::SuspendSlave()' | ||
+ | collect2: ld returned 1 exit status | ||
+ | </file> | ||
+ | **Warning:** some libraries may require to have unresolved symbols. | ||
==== 3. unresolved symbols caused by incorrect order ==== | ==== 3. unresolved symbols caused by incorrect order ==== | ||
- | Two of most difficult of common problems at once, [[http://cvs.pld-linux.org/cgi-bin/cvsweb/SPECS/evolution.spec?rev=HEAD|evolution.spec]]: | + | Two of most difficult of common problems at once, [[http://cvs.pld-linux.org/cgi-bin/cvsweb/SPECS/evolution.spec?rev=HEAD|evolution.spec]]: |
The difficulties are: | The difficulties are: | ||
Line 262: | Line 290: | ||
collect2: ld returned 1 exit status | collect2: ld returned 1 exit status | ||
</file> | </file> | ||
- | function '''convert_ToPilotChar''', may be found in passed library, but take a look at section about positions, arguments order is incorrect: libraries go before objects (conftest.c) it's very common when someone puts ''-l<>'' in ''LDFLAGS'' instead of ''LIBS'', that was the case too | + | function '''convert_ToPilotChar''', may be found in passed library, but take a look at section about positions, arguments order is incorrect: libraries go before objects (conftest.c). It's very common when someone puts ''-l<>'' in ''LDFLAGS'' instead of ''LIBS'', that was the case too. |
- | just take a look at my fix: | + | Just take a look at my fix: |
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+ LIBS="$LIBS_save" | + LIBS="$LIBS_save" | ||
</file> | </file> | ||
- | with this simple change everything works perfectly. | + | With this simple change everything works perfectly. |