Re: EPICS/RTEMS Compilation errors

[Jianxun Yan <yanjx@jlab.org>]

Thank you, Ben.
The linker flags for RTEMS is something like this

c/src/lib/libbsp/arm/altera-cyclone-v/make/custom/altcycv.inc:CPU_CFLAGS 
= -march=armv7-a -mthumb -mfpu=neon -mfloat-abi=hard -mtune=cortex-a9

And for EPICS is
src/tools/O.RTEMS-altcycv_devkit/epics-base-RTEMS-altcycv_devkit.pc:Cflags: 
-I${includedir_osi} -I${includedir_osd} -I${includedir_comp} 
-march=armv7-a -mthumb -mfpu=neon -mfloat-abi=hard -mtune=cortex-a9 
-DUNIX -DMY_DO_BOOTP=NULL

Both RTEMS & EPICS use -mfloat-abi=hard.

The reason causes the error maybe EPICS base is not compatible with 
RTEMS 4.11 yet, just like what Andrew Johnson said.

Thanks,
Jay

On 11/28/2016 12:19 PM, Benjamin Franksen wrote:
> On 28.11.2016 18:06, Michael Davidsaver wrote:
> > On 11/28/2016 11:54 AM, Benjamin Franksen wrote:
> > > On 28.11.2016 15:49, Jianxun Yan wrote:
> > ...
> > > Not sure but
> > >
> > >    ".../librtemscpu.a uses VFP register arguments, libComTestHarness does
> > > not"
> > >
> > > sounds a lot like a mismatch of compiler or linker flags between the BSP
> > > and EPICS.
> > >
> > > Also my first guess for what "VFP" means would be "virtual floating
> > > point" i.e. use FP emulation instead of a 'real' FP unit.
> > VFP = Vector Floating Point aka. hard float.
> >
> > https://www.arm.com/products/processors/technologies/vector-floating-point.php
> >
> > The linker is catching an otherwise hard to detect condition where
> > different object files are compiled with different function calling
> > conventions (ABI).  In this case whether function arguments are pass in
> > VFP registers.
> >
> > The relevant GCC option is '-mfloat-abi=soft|softfp|hard'.  I would
> > guess that different values were given when building the RTEMS libraries
> > vs. EPICS Base.
> >
> > https://gcc.gnu.org/onlinedocs/gcc-4.9.3/gcc/ARM-Options.html#ARM-Options
> Thanks for correcting my half-baked guesses. At least I was right that
> it has to do with a compiler flag mismatch... ;-)
>
> Cheers
> Ben