On Thu, 2017-05-11 at 21:24 +1000, Nicholas Piggin wrote:
> 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 <npig...@gmail.com>
> ---
> Documentation/admin-guide/kernel-parameters.txt | 10 ++++++
> arch/powerpc/Kconfig | 5 ---
> arch/powerpc/kernel/dt_cpu_ftrs.c | 41
> +++++++++++++++++++------
> 3 files changed, 42 insertions(+), 14 deletions(-)
>
> diff --git a/Documentation/admin-guide/kernel-parameters.txt
> b/Documentation/admin-guide/kernel-parameters.txt
> index facc20a3f962..7a7c1cc80f9f 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -867,6 +867,16 @@
>
> 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.
> +
> dump_apple_properties [X86]
> Dump name and content of EFI device properties on
> x86 Macs. Useful for driver authors to determine
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index 5bd868f2e813..c924710e5bc7 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -391,11 +391,6 @@ config PPC_DT_CPU_FTRS
> firmware provides this binding.
> If you're not sure say Y.
>
> -config PPC_CPUFEATURES_ENABLE_UNKNOWN
> - bool "cpufeatures pass through unknown features to guest/userspace"
> - depends on PPC_DT_CPU_FTRS
> - default y
> -
> config HIGHMEM
> bool "High memory support"
> depends on PPC32
> diff --git a/arch/powerpc/kernel/dt_cpu_ftrs.c
> b/arch/powerpc/kernel/dt_cpu_ftrs.c
> index fcc7588a96d6..050925b5b451 100644
> --- a/arch/powerpc/kernel/dt_cpu_ftrs.c
> +++ b/arch/powerpc/kernel/dt_cpu_ftrs.c
> @@ -671,12 +671,24 @@ static struct dt_cpu_feature_match __initdata
> {"wait-v3", feat_enable, 0},
> };
>
> -/* XXX: how to configure this? Default + boot time? */
> -#ifdef CONFIG_PPC_CPUFEATURES_ENABLE_UNKNOWN
> -#define CPU_FEATURE_ENABLE_UNKNOWN 1
> -#else
> -#define CPU_FEATURE_ENABLE_UNKNOWN 0
> -#endif
> +static bool __initdata using_dt_cpu_ftrs = true;
> +static bool __initdata dt_cpu_ftrs_enable_unknown = true;
> +
> +static int __init dt_cpu_ftrs_parse(char *str)
> +{
> + if (!str)
> + return 0;
> +
> + if (!strcmp(str, "off"))
> + using_dt_cpu_ftrs = false;
> + else if (!strcmp(str, "known"))
> + dt_cpu_ftrs_enable_unknown = false;
> + else
> + return 1;
> +
> + return 0;
> +}
> +early_param("dt_cpu_ftrs", dt_cpu_ftrs_parse);
I wouldn't use strcmp with user passed parameters.
Balbir Singh.
