[PATCH v3 2/8] elf: Add a tunable to control use of tagged memory

[Siddhesh Poyarekar]

On 11/28/20 12:07 AM, H.J. Lu wrote:
>>> The memory tag implementation should be independent of tunables.
>>> Tunables should just turn on and off a few bits in the memory tag
>>> implementation.  Make the memory tag implementation depend on
>>> tunables seems wrong to me.

That comment seems to suggest that you'd like to see finer grained 
control over memory tagging in tunables.  Could you elaborate on that? 
If you're suggesting splitting up or adding more tunables, could you 
suggest the splits you'd like to see?

>> That shouldn't matter.  The tunables are documented as not being stable
>> and nothing else is exposed to the user; so if we want to change things
>> later, there's nothing to stop that.
>>
> 
> This is not a good user experience and makes it harder to backport.

I think that's only partly true.  Backporting changes to the *meaning* 
of tunables can be hard to backport, but simply flipping the default 
isn't quite in the same category.

Siddhesh