Re: [PATCH v8 3/3] x86, mce: Add __mcsafe_copy()

On Mon, Jan 11, 2016 at 2:44 AM, Ingo Molnar [off-list ref] wrote:

So such a synthetic CPUID bit would definitely be useful.

Also, knowing whether a memcpy function is recoverable or not, should not be
delegated to callers: there should be the regular memcpy APIs, plus new APIs that
do everything they can to provide recoverable memory copies. Whether it's achieved
via flag checking, a function pointer or code patching is an implementation detail
that's not visible to drivers making use of the new facility.

I'd go for the simplest, most robust solution initially, also perhaps with boot
time messages to make sure users know which variant is used and now.

Are there some examples of synthetic CPUID bits?  I grepped around and
found a handful of places making ad hoc decisions based on sub-strings of
x86_model_id[] ... but didn't find any systematic approach.

-Tony

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