[Barrelfish-users] [ARM] About vfp instructions
kornilios.kourtis at inf.ethz.ch
Fri May 31 15:02:57 CEST 2013
On Thu, May 30, 2013 at 06:41:13PM +0800, Wang Nan wrote:
> Some compiler generates vfp instructions such as vpush, vldr for normal
> code in cpu driver, which introduces complexity (related to fpu state).
> I propose a patch which disables vfp instructions in cpu driver code:
> diff --git a/hake/ARMv7.hs b/hake/ARMv7.hs
> index 142f524..03ed5c4 100644
> --- a/hake/ARMv7.hs
> +++ b/hake/ARMv7.hs
> @@ -116,6 +116,7 @@ kernelCFlags = [ Str s | s <- [ "-fno-builtin",
> + "-mfloat-abi=soft",
Makes sense -- I've applied to our tree. Thanks!
> On the other hand, vfp and A_SIMD instruction should be allowed in user
> code, and fpu state should be saved and restored during context
> switching. In current omap code, I don't find vfp related code. Does
> any one can implements them?
Indeed VFP-aware context switching seems to be missing. We will add it on
our TODO list, but from a quick look it does not seem to be trivial. If
somebody is interested in implementing it, we would be happy to help.
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