How to handle float-point operations
Luis de Bethencourt
luis at debethencourt.com
Wed Jul 1 06:53:49 EDT 2015
On Wed, Jul 01, 2015 at 01:58:30PM +0530, priyaranjan wrote:
> Hi Arun,
> >On Thu, Jun 25, 2015 at 2:33 PM, Arun KS <getarunks at gmail.com> wrote:
> >Hello Mudongliang,
> > >On Tue, Jun 23, 2015 at 9:01 AM, 慕冬亮 <mudongliangabcd at gmail.com> wrote:
> > >>
> > >> I know there are rarely float-point operations! What's the exception?
> > > In the linux kernel, how does it handle the float-point operations in
> > the >userland?
> > >>Most of the userspace programs do not use FP instructions. So by
> > >>default floating point engine is turned off during a context switch.
> > >>When a process executes floating point instruction, an undefined
> > >>exception is generated. Exception handler enables the floating point
> > >>engine and jump back to the same instruction which caused the
> > >>exception so that it will get re executed with FP engine on.
> > Is this somehow related to the platform in which linux runs? If the FP
> > operations are valid, then will that still generate the exception or it
> > does a context switch, turns on FP engine and re-executed?
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