Re: [PATCHv10 09/15] x86: Expose untagging mask in /proc/$PID/arch_status

[Dave Hansen]

On 10/18/22 15:24, Kirill A. Shutemov wrote:
> On Tue, Oct 18, 2022 at 02:02:43PM -0700, Dave Hansen wrote:
>> On 10/18/22 04:33, Kirill A. Shutemov wrote:
>>> Add a line in /proc/$PID/arch_status to report untag_mask. It can be
>>> used to find out LAM status of the process from the outside. It is
>>> useful for debuggers.
>> Considering that address masking is not x86-specific, it seems like this
>> needs a better home (another file in /proc).
> In generic /proc/$PID/status?

Seems like a sane place to me.

> And I'm not sure if it is a good idea at this stage. Semantics around tags
> is not settled across architectures: somewhere it is per-thread, somewhere
> per-process, somewhere it is global.
> 
> Maybe keep it arch-specific?

Yeah, but all of those things could be served by a thread-specific ABI.
The per-thread ABI won't enumerate the scope of the thing, of course.
But, it _can_ precisely communicate what semantics the thread has.