Fwd: Is VFP or Neon supported in kernel-side code? <EOM>
nicolas.pitre at linaro.org
Thu Apr 14 17:33:59 UTC 2011
On Thu, 14 Apr 2011, Tixy wrote:
> 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.
Yes, keeping things simple for now is certainly best. Just save away
your work in case it may become useful eventually.
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