link to librt

[ernfrid]

linking currently fails because librt isn't specified in the linker commands. This adds it, but doesn't check for its existence. This build process is a little more complicated than what I'm personally used to so there may be additional checks that are needed. This allowed us to compile on both Ubuntu 10.04 and 12.10.

[rpetrovski]

iSAAC should not be using librt directly. Can you please post the linker errors?

[ernfrid]

Certainly!

Linking CXX executable isaac-align
/usr/bin/ld: ../lib/build/libisaac_build.a(BinSorter.cpp.o): undefined reference to symbol 'clock_gettime@@GLIBC_2.2.5'
/usr/bin/ld: note: 'clock_gettime@@GLIBC_2.2.5' is defined in DSO /lib64/librt.so.1 so try adding it to the linker command line
/lib64/librt.so.1: could not read symbols: Invalid operation
collect2: ld returned 1 exit status
make[2]: *** [c++/bin/isaac-align] Error 1
make[1]: *** [c++/bin/CMakeFiles/isaac-align.dir/all] Error 2
make: *** [all] Error 2

In case it is helpful:

gcc --version
gcc (Ubuntu/Linaro 4.6.4-1ubuntu1~10.04) 4.6.4
Copyright (C) 2011 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

ld --version
GNU ld (GNU Binutils for Ubuntu) 2.22
Copyright 2011 Free Software Foundation, Inc.
This program is free software; you may redistribute it under the terms of
the GNU General Public License version 3 or (at your option) a later version.
This program has absolutely no warranty.

We observed similar errors with Ubuntu 12.04 although in this case they were of a slightly different form:

Linking CXX executable isaac-reorder-reference

../../bootstrap/lib/libboost_thread.a(thread.o): In function `boost::this_thread::hiden::sleep_until(timespec const&)':

thread.cpp:(.text+0x1660): undefined reference to `clock_gettime'

thread.cpp:(.text+0x16d1): undefined reference to `clock_gettime'

thread.cpp:(.text+0x173c): undefined reference to `clock_gettime'

thread.cpp:(.text+0x17a7): undefined reference to `clock_gettime'

thread.cpp:(.text+0x1812): undefined reference to `clock_gettime'

../../bootstrap/lib/libboost_thread.a(thread.o):thread.cpp:(.text+0x187d): more undefined references to `clock_gettime' follow

collect2: ld returned 1 exit status

make[2]: *** [c++/bin/isaac-reorder-reference] Error 1

make[1]: *** [c++/bin/CMakeFiles/isaac-reorder-reference.dir/all] Error 2

make: *** [all] Error 2

Both were resolved by adding in the rt library as in the pull request.

[rpetrovski]

I've put in an update iSAAC-01.14.04.01 which adds librt if it is available. Please tell me if this fixes the issue.

Roman.

[ernfrid]

Yes, iSAAC now links without error! I still need to run the configuration twice in order for the redistributed Boost libraries to be detected (as described in issue #8).