looks in liblapack.a not liblapack.so

On Tue, Sep 20, 2005 at 09:43:51PM -0500, Luke Tierney wrote:

On Tue, 20 Sep 2005, Charles Geyer wrote:

I still don't understand why gcc -shared even bothers to look in *.a
(on AMD64) when it won't do the slightest bit of good.  Maybe I'm still
ignorant of some important technical issue (maybe? more like with very
high probability!)

The issue is not the library but whether the code is compiled as
position-independent code (PIC) or not.  Many .a libraries are built
as PIC and they can be used to create shared objects, you just get
copies of the modules you use linked in.  PIC code can be slower,
which is why some prefer to build .a libraries as non-PIC.

Oh.  Thanks.  That makes it all clear.  If I compile cddlib with

   export CXX=gcc
   export CFLAGS="-O -fPIC"
   ./configure --prefix=/APPS/64/

then I can build rcdd and it works!  (And, you're right, the fact that
cddlib builds libcddgmp.a instead of libcddgmp.so is irrelevant, it's
the -fPIC that matters.)

I'm not sure why one rarely runs into non-PIC issues on i386--it may
be that gcc at least is always producing PIC code there.  It does come
up on other architectures though, in particular on x86_64.  It seems
that most Linux distros that provide pvm only provide .a libraries,
but some build these with PIC some don't.  Red Hat Enterprise WS4
seems to be non-PIC, FC3 and FC4 seem to be PIC.  If your distro is
non-PIC you will need to build your own PIC version of pvm and tell
rpvm where to find it.

   snowbank$ locate pvm | grep -E '\.so|\.a$'
   /usr/lib/pvm3/lib/LINUX64/libfpvm3.a
   /usr/lib/pvm3/lib/LINUX64/libgpvm3.a
   /usr/lib/pvm3/lib/LINUX64/libpvm3.a
   /usr/lib/pvm3/lib/LINUX64/libpvmtrc.a
   /usr/lib64/libpvm3.so
   /usr/lib64/libpvm3.so.3
   /usr/lib64/libpvm3.so.3.4

I think I've got the libraries, so

 > install.packages("rpvm", repos = "http://www.biometrics.mtu.edu/CRAN/")

 trying URL 'http://www.biometrics.mtu.edu/CRAN/src/contrib/rpvm_0.6-5.tar.gz'

 [lots of blather deleted]

 gcc -shared -L/usr/local/lib64 -o rpvm.so rpvm_core.o rpvm_ser.o utils.o -L/usr/lib/pvm3/lib/LINUX64 -lpvm3 -lgpvm3 -lreadline -lncurses
 /usr/lib64/gcc-lib/x86_64-suse-linux/3.3.5/../../../../x86_64-suse-linux/bin/ld: /usr/lib/pvm3/lib/LINUX64/libpvm3.a(lpvmgen.o): relocation R_X86_64_32 against `a local symbol' can not be used when making a shared object; recompile with -fPIC

same problem, I have a .so (presumably PIC), but it's picked another library.
Reading the help for install.packages, I don't find anything about how to
make it link against /usr/lib64/libpvm3.so instead
of /usr/lib/pvm3/lib/LINUX64/libpvm3.a so I guess that means do it by hand.

I'm a little puzzled by that too.  Apparently the configure in rpvm wants
to use PVM_ROOT which for this (SuSE 9.3 AMD64) box is /usr/lib/pvm3 (which
is the default) to find the libraries it wants to link to, but that won't
work.  The appropriate library is /usr/lib64/libpvm3.so -- maybe.
I just noticed the -lpvm3 -lgpvm3 in the link that failed.  I'm not
sure /usr/lib64/libpvm3.so contains everything rpvm needs.
This just isn't going to work with the SuSE provided pvm stuff right?

I untarred the rpvm package and did R CMD check on it and it really
doesn't give any way to link to a library in an odd place -- at least
not that I can see.