Experimental Physics and
Industrial Control System

Andrew Johnson via Core-talk <[email protected]> · Wed, 28 Aug 2019 16:23:50 -0000

Thanks, I will commit that change.

When we were developing devLib we noted that linkers see a difference
between

  devLibVME *pdevLibVME = NULL;

and

  devLibVME *pdevLibVME;

The latter is better because you can link the second compiled definition
with another object file that contains

  devLibVME *pdevLibVME = { ... };

whereas using the first definition the linker could object to the
redefinition. Not sure if that's still the case, but it's good to be
aware of the deliberate difference. The only place we have the first one
is in the cygwin32 implementation, which will never talk to a real
VMEbus.

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https://bugs.launchpad.net/bugs/1841692

Title:
  Non-VME RTEMS targets should define pdevLibVME

Status in EPICS Base:
  In Progress
Status in EPICS Base 7.0 series:
  In Progress

Bug description:
  Support modules that build IOCs with drivers that call devLib routines
  can't be compiled on non-VME RTEMS targets such as RTEMS-pc386 since
  the linker fails to find the symbol pdevLibVME. The build *only* fails
  for RTEMS targets though, other non-VME targets such as Windows or
  darwin will quite happily compile and link the IOC code. This makes
  the authors of support modules have to jump through hoops to ensure
  they don't build IOCs for targets that will fail, or to just let the
  build fail (many sites don't build for RTEMS anyway).

  The RTEMS implementation of devLibVMEOSD.c uses pre-processor
  conditionals to only define the devLibVME *pdevLibVME pointer inside
  #if defined(__PPC__) || defined(__mcf528x__)

  We could make life much easier for module authors by adding this:

  diff --git a/modules/libcom/src/osi/os/RTEMS/devLibVMEOSD.c b/modules/libcom/src/osi/os/RTEMS/devLibVMEOSD.c
  index 0a96bad..b8f79e7 100644
  --- a/modules/libcom/src/osi/os/RTEMS/devLibVMEOSD.c
  +++ b/modules/libcom/src/osi/os/RTEMS/devLibVMEOSD.c
  @@ -350,7 +350,12 @@ static void unsolicitedHandlerEPICS(int vectorNumber)
           );
   }

  -#endif /* defined(__PPC__) && defined(mpc750) */
  +#else /* !defined(__PPC__) && !defined(__mcf528x__) */
  +
  +/* No known VME interface here, provide a dummy */
  +devLibVME *pdevLibVME;
  +
  +#endif /* defined(__PPC__) || defined(__mcf528x__) */

   /*
    * Some vxWorks convenience routines

  With that change (which is identical to the osi/os/default version),
  the non-VME RTEMS targets will build exactly the same as the
  workstation OS targets; an IOC that calls devLib will now compile,
  although it obviously won't actually work if booted.

  Any objections?

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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System