Re: [PATCH 3/3] x86/fpu: Don't support kernel-mode FPU when irqs_disabled()

[Ingo Molnar]

* Eric Biggers <ebiggers@xxxxxxxxxx> wrote:

> > Alternatively we could set in_kernel_fpu during CPU bootstrap, and 
> > clear it once we know the FPU is usable? This is only a relatively 
> > short early boot period, with no scheduling, right?
> 
> Yes, if there isn't agreement on this approach we can do that 
> instead.  Say:
> 
> - Replace in_kernel_fpu with kernel_fpu_supported, with the opposite 
>   meaning (so that the initial value of false means "unsupported")

I'm not against simplifying the x86 FPU model to exclude IRQs-off
context (especially if it also micro-optimizes some of the key runtime
kernel-FPU primitives), but it has to be a full solution and we'll have
to see how complicated the EFI changes get.

Ie. without seeing the full cost-benefit balance it's hard to call this
in advance. Mind sending a full series that addresses the EFI case too?

Thanks,

	Ingo