[PATCH 3/3] arm: vfp: Bounce undefined instructions in vectored mode

Will Deacon will.deacon at arm.com
Thu Sep 18 18:40:01 PDT 2014

On Thu, Sep 18, 2014 at 11:55:31PM +0100, Russell King - ARM Linux wrote:
> On Thu, Sep 18, 2014 at 02:43:12PM -0700, Stephen Boyd wrote:
> > From: Stepan Moskovchenko <stepanm at codeaurora.org>
> > 
> > Certain ARM CPU implementations (e.g. Cortex-A15) may not raise a
> > floating- point exception whenever deprecated short-vector VFP
> > instructions are executed. Instead these instructions are treated
> > as UNALLOCATED. Change the VFP exception handling code to emulate
> > short-vector instructions even if FPEXC exception bits are not
> > set.
> Purely out of interest, how much use do these instructions have in
> real programs?

They're seldom used, but there are apps in the app store that use short
vectors to play music.


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