Re: [PATCH 3/7] x86: make CX8 usage unconditional

[Arnd Bergmann]

>> -	asm_inline qual (						\
>> -		ALTERNATIVE("call this_cpu_cmpxchg8b_emu",		\
>> -			    "cmpxchg8b " __percpu_arg([var]), X86_FEATURE_CX8) \
>> -		: ALT_OUTPUT_SP([var] "+m" (__my_cpu_var(_var)),	\
>> -				"+a" (old__.low), "+d" (old__.high))	\
>> +	asm_inline qual ("cmpxchg8b " __percpu_arg([var])		\
>
> This can be plain "asm" instead of "asm_inline"; there is only one asm 
> instruction in the asm template.
>
>> +		: [var] "+m" (__my_cpu_var(_var)),			\
>> +				"+a" (old__.low), "+d" (old__.high)	\
>>   		: "b" (new__.low), "c" (new__.high),			\
>>   		  "S" (&(_var))						\
>
> The line above was needed to force address of _var in %esi. This is not 
> needed anymore.
>>   		: "memory");						\
>> @@ -359,10 +357,8 @@ do {									\
>>   	old__.var = *_oval;						\
>>   	new__.var = _nval;						\
>>   									\
>> -	asm_inline qual (						\
>> -		ALTERNATIVE("call this_cpu_cmpxchg8b_emu",		\
>> -			    "cmpxchg8b " __percpu_arg([var]), X86_FEATURE_CX8) \
>> -		: ALT_OUTPUT_SP("=@ccz" (success),			\
>> +	asm_inline qual ("cmpxchg8b " __percpu_arg([var])		\
>
> Also here, use "asm" and remove "S" constraint. Please see [1].
>
> [1] 
> https://git.kernel.org/pub/scm/linux/kernel/git/mingo/tip.git/commit/?h=WIP.x86/cpu&id=8cfdd354dae90a3db46c351d15c801dfbf76fc5a
>

Hi Uros,

Thanks for the suggestions, I changed it all as you suggested now.

      Arnd