Denormalised numbers on arm

[Andrew Turner]

On Sun, 7 Jun 2015 10:43:14 +1000
Peter Jeremy <peter at rulingia.com> wrote:

> I've been tracking down the cause of some test failures on my RPi
> (running armv6hf head r283107) and found that denormalised numbers are
> flushed to zero.  This appears deliberate (r263913 initialised the
> fpscr so denormalised numbers are flushed to zero) but isn't what is
> expected from IEEE FP arithmetic.  The commit doesn't include any
> explanation for setting this (mis)behaviour.
> 
> Can someone explain why Arm defaults to flush-to-zero?

Not all VFP units support subnormal inputs. Because of this we would
need to add code to the kernel to support these. As we don't have this
code I disabled them.

Andrew
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