Experimental Physics and
Industrial Control System

Benjamin Franksen <[email protected]> · Mon, 28 Nov 2016 18:19:22 +0100

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
-- 
"Make it so they have to reboot after every typo." ― Scott Adams

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System