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On 25/11/15 14:07, Matthew Knepley wrote:<br>
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<div class="gmail_quote">On Wed, Nov 25, 2015 at 6:16 AM,
Arne Morten Kvarving <span dir="ltr"><<a
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href="mailto:arne.morten.kvarving@sintef.no"><a class="moz-txt-link-abbreviated" href="mailto:arne.morten.kvarving@sintef.no">arne.morten.kvarving@sintef.no</a></a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">hi,<br>
<br>
a while back i was told to use the .pc file for petsc if
i wanted pkgconfig style (duh) configuration.<br>
i used to use a (confusingly named) PETScConfig.cmake
file for this, which was not intended for such use.<br>
<br>
problem now is that the pc file of petsc is a bit
broken.<br>
<br>
in particular, i want to link petsc static, but not all
the dependencies. if i build petsc (static or not),<br>
the lib entry is listed as<br>
<br>
Libs: -L<path-to-petsc-configuration>/lib -lpetsc<br>
<br>
now, the dependencies are listed in<br>
<br>
Libs.private: /usr/lib/liblapack.a /usr/lib/libblas.a
libX11.a libpthread.a libssl.a libcrypto.a libhwloc.a
libm.a -L/usr/lib/gcc/x86_64-linux-gnu/4.9
-L/usr/lib/x86_64-linux-gnu -L/lib/x86_64-linux-gnu
-lgfortran -lm -lgfortran -lm -lquadmath -lm
-L/usr/lib/gcc/x86_64-linux-gnu/4.9
-L/usr/lib/x86_64-linux-gnu -L/lib/x86_64-linux-gnu
-lstdc++ -L/usr/lib/gcc/x86_64-linux-gnu/4.9
-L/usr/lib/x86_64-linux-gnu -L/lib/x86_64-linux-gnu
-L/usr/lib/x86_64-linux-gnu -ldl -lgcc_s -ldl -ldl<br>
<br>
which are for a totally static link (you'd use --static
with pkg-config to obtain it).<br>
<br>
the problem with a totally static link, however, is that
pkg-config returns this:<br>
<br>
pkg-config --static --libs PETSc -><br>
<br>
/usr/lib/liblapack.a /usr/lib/libblas.a libX11.a
libpthread.a libssl.a libcrypto.a libhwloc.a libm.a
-L/home/akva/kode/petsc/current/linux-gnu-cxx-opt/lib
-L/usr/lib/gcc/x86_64-linux-gnu/4.9 -lpetsc -lgfortran
-lquadmath -lm -lstdc++ -lgcc_s -ldl<br>
<br>
which breaks at linking because petsc won't see any of
the symbols in those .a files before (static link is
order dependent).<br>
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<div>I do not understand this explanation.</div>
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<div>1) Why does the link fail? Please send the error.</div>
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it's because with static linking, the order of libraries matter.
if you do<br>
<br>
-lfoo -lbar<br>
<br>
the linker will see the symbols in the bar library when linking
foo, but not the other way around. <br>
thus the linker do not see the symbols in e.g. libX11.a when
linking petsc and you get a lots of inker errors,<br>
<br>
random line; <br>
<br>
xops.c:(.text+0x2a9): undefined reference to `XSetForeground'<br>
xops.c:(.text+0x3e0): undefined reference to `XDrawLine'<br>
/home/akva/kode/petsc/current/linux-gnu-cxx-opt/lib/libpetsc.a(xops.o):
In function `PetscDrawArrow_X(_p_PetscDraw*, double, double,
double, double, int)':<br>
<br>
<br>
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<div>2) Is pkgconfig changing/filtering the link line?
That would seem like a bug in pkgconfig.</div>
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yes, pkg-config is behaving very weird. i have no idea of the
logic here, it's likely a bug.<br>
<br>
if I<br>
1) move Libs.private below Libs in the .pc file<br>
2) replace the absolute references to archive foo.a with -lfoo<br>
<br>
it works. i.e.<br>
<br>
using <a moz-do-not-send="true" class="moz-txt-link-freetext"
href="http://paste.ubuntu.com/13502223/">http://paste.ubuntu.com/13502223/</a>
(ignore the irrelevant changes, that is using the variables
instead of absolute paths), i get<br>
/usr/lib/liblapack.a /usr/lib/libblas.a libX11.a libpthread.a
libssl.a libcrypto.a libhwloc.a libm.a
-L/home/akva/kode/petsc/current/linux-gnu-cxx-opt/lib
-L/usr/lib/gcc/x86_64-linux-gnu/4.9 -lpetsc -lgfortran -lquadmath
-lm -lstdc++ -lgcc_s -ldl<br>
<br>
which breaks (so step 1 is not enough).<br>
<br>
if i however use <a moz-do-not-send="true"
class="moz-txt-link-freetext"
href="http://paste.ubuntu.com/13502228/">http://paste.ubuntu.com/13502228/</a><br>
<br>
i get<br>
<br>
-L/home/akva/kode/petsc/current/linux-gnu-cxx-opt/lib
-L/usr/lib/gcc/x86_64-linux-gnu/4.9 -lpetsc -llapack -lblas -lX11
-lpthread -lssl -lcrypto -lhwloc -lm -lstdc++ -lgcc_s -ldl <br>
<br>
as wanted (missing a few -L's in principle for the last file).<br>
<br>
this is with pkg-config 0.26 (ubuntu trusty).<br>
<br>
arnem<br>
<br>
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