Re: PROC vs PROC_HOST

[Andrew Johnson <anj@aps.anl.gov>]

Hi Richard,

On 10/08/2014 05:46 AM, Doucet, Richard wrote:
> Ran into a problem when trying to cross-compile an EPICS application for
> the ARM architecture under a Linux x86_64 host.  My build created both
> the x86 and x86_64 binary, but would not create the ARM.  I eventually
> change the application makefile:
> 
> PROC_HOST = myApplication

I think you probably mean PROD_HOST and PROD, I will assume that
substitution for the remainder of this message...

> to
> 
> PROC = myApplication
> 
> This caused ARM version to compile, but it failed due to missing
> libraries in the base, specifically asHost and dbStaticHost.  Looking at
> the makefile for those library, I noticed that it had
> 
> LIBRARY_HOST = dbStaticHost
> 
> and
> 
> LIBRARY_HOST = asHost
> 
> These are the only two libraries from the EPICS base I found that define
> the target using the LIBRARY_HOST (macro?) instead of LIBRARY.
> 
> I changed both of these to LIBRARY, recompiled the EPICS based, then
> successfully recompiled the ARM version of my application.
> 
> Is there a reason why these two libraries are defined as LIBRARY_HOST
> instead of just LIBRARY?

Those two libraries are not need for IOC applications, they are only
used by tools that run on the build host (that's what the _HOST suffix
generally means in our build system). We assume that cross-compiled
targets will not need the host tools, so we don't waste time building
them. Some of the cross-build targets we support such as iOS don't
provide all of the OS features that the host tools rely on, so they
can't be built there at all.

Why is this application linking to these libraries instead of the IOC
run-time versions dbStaticIoc and asIoc? How is your Makefile specifying
which EPICS libraries it should link against, and does the application
actually need any routines from dbStaticHost and/or asHost?

- Andrew