Re: [PATCH V3 05/10] x86/entry: Pass irqentry_state_t by reference

Thomas Gleixner
2020-11-15T18:59:06Z

Ira,

On Fri, Nov 06 2020 at 15:29, ira weiny wrote:

Subject prefix wants to 'entry:'. This changes generic code and the x86
part is just required to fix the generic code change.

> Currently struct irqentry_state_t only contains a single bool value
> which makes passing it by value is reasonable. However, future patches
> propose to add information to this struct, for example the PKRS
> register/thread state.
>
> Adding information to irqentry_state_t makes passing by value less
> efficient. Therefore, change the entry/exit calls to pass irq_state by
> reference.

The PKRS muck needs to add an u32 to that struct. So how is that a
problem?

The resulting struct still fits into 64bit which is by far more
efficiently passed by value than by reference. So which problem are you
solving here?

Thanks

tglx