On Fri, Oct 12, 2018 at 10:52 AM Vincent Chen <vince...@andestech.com> wrote: > > On Thu, Oct 11, 2018 at 03:30:30PM +0800, Arnd Bergmann wrote: > > On Thu, Oct 11, 2018 at 4:56 AM Vincent Chen <vince...@andestech.com> wrote:
> > There was a long discussion on RISC-V about what happens when > > FPU support is enabled or disabled, you may have seen that as well. > > > > Can you confirm that: > > > > a) A kernel with FPU support enabled running on a CPU without an FPU > > will behave the same as a kernel without FPU support, and in particular > > not crash while trying to access the FPU > > b) A kernel with FPU support disabled running on a CPU with an FPU > > prevents user space from accessing the FPU, to avoid corrupting > > FPU registers during a task switch when a process accidentally contains > > FPU access > > In this patch user program will be terminated when accessing FPU register > if the FPU support is disabled on kernel. Hence, condition b) is promised. > Condition a) is unsupported in this patch. I will add this support in > the next version patch. Ok, sounds good, thanks Arnd
