Re: [PATCH resend] MIPS: Allow FPU emulator to use non-stack area.

From: Rich Felker
Date: Mon Oct 06 2014 - 20:06:28 EST


On Mon, Oct 06, 2014 at 04:48:52PM -0700, David Daney wrote:
> On 10/06/2014 04:38 PM, Andy Lutomirski wrote:
> >On 10/06/2014 02:58 PM, Rich Felker wrote:
> >>On Mon, Oct 06, 2014 at 02:45:29PM -0700, David Daney wrote:
> [...]
> >>This is a huge ill-designed mess.
> >
> >Amen.
> >
> >Can the kernel not just emulate the instructions directly?
>
> In theory it could, but since there can be implementation defined
> instructions, there is no way to achieve full instruction set
> coverage for all possible machines.

Is the issue really implementation-defined instructions with delay
slots? If so it sounds like a made-up issue. They're not going to
occur in real binaries. Certainly a compiler is not going to generate
implementation-defined instructions, and if you're writing the asm by
hand, you just don't put floating point instructions in the delay
slot.

Rich
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