Re: [PATCH v7 1/5] arm64: Enable EDAC on ARM64

Loc Ho
2015-04-29T21:39:27Z

Hi,

>> +/*
>> + * ECC atomic, DMA, SMP and interrupt safe scrub function.
>> + * Implements the per arch atomic_scrub() that EDAC use for software
>> + * ECC scrubbing. It reads memory and then writes back the original
>> + * value, allowing the hardware to detect and correct memory errors.
>> + */
>
> The comment here is misleading since the function doesn't do anything.

Okay.. I will leave only this line:

ECC atomic, DMA, SMP and interrupt safe scrub function.

>> +static inline void atomic_scrub(void *va, u32 size)
>> +{
>> + /* Stub function for now until an ARM64 HW has a way to test it. */
>> +}
>
> Can we have a WARN_ONCE() here?
>
> We had some discussions last year, restarted this year and the
> conclusion was to leave this function as a no-op since it is not safe in
> the presence of KVM or non-coherent DMA:
>
> http://lists.infradead.org/pipermail/linux-arm-kernel/2015-March/326986.html

I will leave WARN_ONCE.

-Loc