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

[H.J. Lu]

On Thu, Nov 26, 2020 at 6:45 PM Siddhesh Poyarekar <siddhesh@gotplt.org> wrote:
>
> On 11/26/20 10:49 PM, H.J. Lu wrote:
> > The first few questions are
>
> OK this is a good start:
>
> > 1.  Where should binary markers be checked?
>
> At early startup alongside the cpu features resolution.  We enable
> tagging if the CPU supports MTE and the marker is set.

We won't know all the issues before we implement it.

> > 2.  How should binary marker checking work together with tunables?
>
> The presence of a binary marker enables tagging and a tunable should not
> be able to disable it.  The exception would be systemwide tunables[1]
> where administrators could set sweeping policies for their systems,
> including disabling tagging systemwide if needed.

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.

> If binary marker is not present, tunables behave the way it is proposed
> in the patchset.
>
> Siddhesh
>
> [1] Vapourware alert!



-- 
H.J.