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

[Michael Ellerman <mpe@ellerman.id.au>]

Balbir Singh <bsingharora@gmail.com> writes:
> On Thu, 2017-05-11 at 21:24 +1000, Nicholas Piggin wrote:
>> 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.

Why not? Especially considering the generic code has already parsed the
string to find the = delimiter, and is just passing us the tail.

cheers