Re: [PATCH v2] powerpc/64s: Add dt_cpu_ftrs boot time setup option

[Nicholas Piggin <npiggin@gmail.com>]

On Tue, 30 May 2017 16:28:09 +1000
Michael Ellerman <mpe@ellerman.id.au> wrote:

> From: Nicholas Piggin <npiggin@gmail.com>
> 
> Provide a dt_cpu_ftrs= cmdline option to disable the dt_cpu_ftrs CPU
> feature discovery, and fall back to the "cputable" based version.
> 
> Also allow control of advertising unknown features to userspace and
> with this parameter, and remove the clunky CONFIG option.
> 
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> [mpe: Add explicit early check of bootargs in dt_cpu_ftrs_init()]

Thanks for fixing that up. The patch is more yours than mine now :P

> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -866,6 +866,16 @@
>  
>  	dscc4.setup=	[NET]
>  
> +	dt_cpu_ftrs=	[PPC]
> +			Format: {"off" | "known"}
> +			Control how the dt_cpu_ftrs device-tree binding is
> +			used for CPU feature discovery and setup (if it
> +			exists).
> +			off: Do not use it, fall back to legacy cpu table.
> +			known: Do not pass through unknown features to guests
> +			or userspace, only those that the kernel is not aware
> +			of.

Well that's not the right number of nots. Better make it:

+			known: Do not pass through unknown features to guests
+			or userspace, only those that the kernel is not not
+			aware of.