Fwd: Is VFP or Neon supported in kernel-side code? <EOM>
tixy at yxit.co.uk
Thu Apr 14 16:14:50 UTC 2011
On Thu, 2011-04-14 at 17:02 +0100, Dave Martin wrote:
> Currently, no.
> There is some possible future work to see if we can enable this, to
> allow acceleration of some number-crunching algorithms in the kernel,
> but it's not implemented yet.
> For now, I think it's reasonable simply to reject attempts to insert
> kprobes on VFP/NEON instructions (as we must for cp15). I think that
> these instructions are never used at the entry/exit points of
> compiler-generated functions -- in any case, we build the kernel with
> -msoft-float, so actually the compiler should never implicitly
> generate these instructions at all.
That'll save some tricky test code writing for now. I've tidied up and
fixed the coprocessor instruction decoding for kprobes, but it sounds
like there isn't much use for this and it could just be deleted.
Nicolas might have an opinion.
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