[PATCH v2] powerpc/book3s/mm: Update Oops message to print the correct translation in use

[Christophe Leroy]

Le 12/07/2019 à 14:22, Michael Ellerman a écrit :
> Christophe Leroy <christophe.leroy at c-s.fr> writes:
>> Le 12/07/2019 à 08:25, Michael Ellerman a écrit :
>>> "Aneesh Kumar K.V" <aneesh.kumar at linux.ibm.com> writes:
> ...
>>>> diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
>>>> index 11caa0291254..b181d6860f28 100644
>>>> --- a/arch/powerpc/kernel/traps.c
>>>> +++ b/arch/powerpc/kernel/traps.c
>>>> @@ -250,15 +250,22 @@ static void oops_end(unsigned long flags, struct pt_regs *regs,
>>>>    }
>>>>    NOKPROBE_SYMBOL(oops_end);
>>>>    
>>>> +static char *get_mmu_str(void)
>>>> +{
>>>> +	if (early_radix_enabled())
>>>> +		return " MMU=Radix";
>>>> +	if (early_mmu_has_feature(MMU_FTR_HPTE_TABLE))
>>>> +		return " MMU=Hash";
>>>> +	return "";
>>>> +}
>>>
>>> We don't change MMU once we're up, so just do this logic once and stash
>>> it into a static string, rather than rechecking on every oops.
>>
>> Do we really have oops so often that we have to worry about that ?
> 
> Sometimes :)
> 
> But no I don't mean it's a performance issue, it just seems simpler to
> compute the value once and store it. In fact for most platforms it can
> just be a static string at compile time, it's only 64-bit Book3S that
> needs to do anything at runtime.

Right, but I'm sure GCC will take care of that since the function is 
static and called only once.

Christophe
> 
> cheers
>