Re: aarch64: Memory tagging modes proposal

On Tue, Aug 25, 2026 at 10:07:31AM -0300, Adhemerval Zanella Netto wrote:
>
> ...
>
> The deeper problem is that the tunable answers two orthogonal questions
> with one value:
> 
> * which fault mode?
> * is heap tagging enabled for unmarked binaries?

Technically, these are orthogonal, but

 | ---------------------------- |
 |  on  | sync | async | etc... |
 | ---------------------------- |
 |  off |  --  |  --   |  --    |
 | ---------------------------- |

there is only one dimension of meaningful combinations.

> Which means neither can be expressed independently.

Can you give an example that cannot be expressed?

> An admin who wants heap
> tagging on unmarked binaries but has no opinion on mode to select

What do you mean by "has no option for mode to select"? Tunable allows
you to select any mode. And unless mode is off, I don't see any issue
here.

> , it will
> always need to use the kernel default.

Nobody has to use kernel default mode unless they want to. Choose
tunable value that works for your use case and use it.

Thanks,
Yury