Hi Ralph,

On 01/11/2018 04:16 AM, Ralph Lange wrote:
> Moving from RHEL6 to RHEL7, we ran into the issue that with the newer
> system the linker line for an executable has to mention all intermediate
> dependencies, while on RHEL6 is was good enough that intermediate
> dependency libraries were mentioned in the internal dependency list
> (output of 'ldd') of a primary dependency library.

Huh?

> tux% cat /etc/redhat-release
> Red Hat Enterprise Linux Workstation release 7.4 (Maipo)
> tux% make softIoc
> make -f ../Makefile TOP=../../.. T_A=linux-x86_64  softIoc
> make[1]: Entering directory '/epics/base/7.0/modules/database/src/std/O.linux-x86_64'
> /usr/bin/g++ -o softIoc  -L/epics/base/7.0/lib/linux-x86_64
>   -Wl,-rpath,/epics/base/7.0/lib/linux-x86_64 -rdynamic -m64
>   softIoc_registerRecordDeviceDriver.o softMain.o -ldbRecStd -ldbCore -lca -lCom
> make[1]: Leaving directory '/epics/base/7.0/modules/database/src/std/O.linux-x86_64'

There is no -lpthread on that line. Are you using a different linker
(gold perhaps?).

> As a result of the missing intermediate dependency, you get error
> messages like
>
>     /usr/bin/ld: PIDThread.o: undefined reference to symbol 'pthread_create@@GLIBC_2.2.5'
>     /usr/lib64/libpthread.so.0: error adding symbols: DSO missing from command line

Why do you think you get those errors but I've never seen them here on
RHEL-7? Can you name a standard EPICS module where you're seeing this so
I can try to replicate it (I assume it doesn't happen with Base builds
or you would have reported it earlier)?

> At first glance, the setting of POSIX_LDLIBS
> (in CONFIG.Common.linuxCommon) seems to try to avoid this for pthreads,
> but it turns out that this is added only (in CONFIG.Common.UnixCommon)
> for STATIC_BUILD = YES or SHARED_LIBRARIES = NO.
>
> How should we address this?

I would like to be able to see it here to understand what's going on
before we make any build system changes. Can you post the full
command-line that generates the error please.

I'm going to guess that this is an ITER source file. Does its Makefile
contain  SYS_LIBS += pthread  which I think should be needed to build
any code that is calling pthread routines directly?

Also make sure that you have rebuilt everything on RHEL-7, I do have a
vague recollection of seeing that error here recently, and I think the
fix was that we needed to rebuild something after the upgrade.

- Andrew

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