[PATCH v1 12/38] arm64/sme: Provide ABI documentation for SME

[Szabolcs Nagy]

The 09/30/2021 19:11, Mark Brown wrote:
> --- /dev/null
> +++ b/Documentation/arm64/sme.rst
> @@ -0,0 +1,427 @@
> +===================================================
> +Scalable Matrix Extension support for AArch64 Linux
> +===================================================
> +
> +This document outlines briefly the interface provided to userspace by Linux in
> +order to support use of the ARM Scalable Matrix Extension (SME).
> +
> +This is an outline of the most important features and issues only and not
> +intended to be exhaustive.  It should be read in conjunction with the SVE
> +documentation in sve.rst which provides details on the Streaming SVE mode
> +included in SME.
> +
> +This document does not aim to describe the SME architecture or programmer's
> +model.  To aid understanding, a minimal description of relevant programmer's
> +model features for SME is included in Appendix A.
> +
> +
> +1.  General
> +-----------
> +
> +* PSTATE.SM and PSTATE.ZA, the streaming mode vector length and the ZA
> +  register state are tracked per thread.

can you add a note that there is a new TPIDR2_EL0
per thread and on thread creation it's 0 (and i
guess unchanged on fork).

at least this abi makes most sense to me.