Re: [PATCH] powerpc/64: Reclaim CPU_FTR_SUBCORE

[Balbir Singh <bsingharora@gmail.com>]

On Mon, 29 May 2017 11:53:10 +1000
Michael Ellerman <mpe@ellerman.id.au> wrote:

> We are running low on CPU feature bits, so we only want to use them when
> it's really necessary.
> 
> CPU_FTR_SUBCORE is only used in one place, and only in C, so we don't
> need it in order to make asm patching work. It can only be set on
> "Power8" CPUs, which in practice means POWER8, POWER8E and POWER8NVL.
> There are no plans to implement it on future CPUs, but if there ever
> were we could retrofit it then.
> 
> Although KVM uses subcores, it never looks at the CPU feature, it either
> looks at the ISA level or the threads_per_subcore value.
> 
> So drop the CPU feature and do a PVR check instead. Drop the device tree
> "subcore" feature as we no longer support doing anything with it, and we
> will drop it from skiboot too.
> 
> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
> ---

Acked-by: Balbir Singh <bsingharora@gmail.com>

I looked at CPU_FTR_DBELL and its used for initialization and in
arch_show_interrupts(), no assembly

it may be another candidate for reclaim

Balbir Singh.