fpu/softfloat: a question on BFloat 16 support on QEMU

[LIU Zhiwei]

Hi Richard,

I am doing bfloat16 support on QEMU.
Once I tried to reuse float32 interface, but I couldn't properly process 
rounding in some insns like fadd.

What's your opinion about it? Should I expand the fpu/softfloat?

Best Regards,
Zhiwei