Re: EPICS/RTEMS Compilation errors

[Michael Davidsaver <mdavidsaver@gmail.com>]

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

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