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SubjectRe: [RFC PATCH v4 05/13] riscv: Add new csr defines related to vector extension
On Mon, Jun 1, 2020 at 4:15 PM Greentime Hu <greentime.hu@sifive.com> wrote:
>
> Guo Ren <guoren@kernel.org> 於 2020年5月31日 週日 上午9:56寫道:
> >
> > Hi Greentime,
> >
> > Why remove vxrm and xstat ?
> >
> > > Appendix B: Calling Convention
> > > In the RISC-V psABI, the vector registers v0-v31 are all caller-saved. The vstart, vl, and vtype CSRs are also caller-saved.
> > > The vxrm and vxsat fields have thread storage duration.
> >
> Hi Guo,
>
> https://github.com/riscv/riscv-v-spec/blob/master/v-spec.adoc#vector-control-and-status-register-vcsr
> "The vxrm and vxsat separate CSRs can also be accessed via fields in
> the vector control and status CSR, vcsr."
>
> Since vcsr will save all these information, I think it should be ok to
> save vcsr only.

Got it, it's similar with fcsr & frm & fflags.

Acked-by: Guo Ren <guoren@kernel.org>

--
Best Regards
Guo Ren

ML: https://lore.kernel.org/linux-csky/

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