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From:   Guo Ren <guoren@kernel.org>
Date:   Mon, 1 Jun 2020 16:59:47 +0800
Message-ID: <CAJF2gTRk3hUmqOb4dhCWhLZq6tznwVLWGe5M4jY4D+DS+P6vNQ@mail.gmail.com>
Subject: Re: [RFC PATCH v4 05/13] riscv: Add new csr defines related to vector extension
To:     Greentime Hu <greentime.hu@sifive.com>
Cc:     Guo Ren <guoren@linux.alibaba.com>,
        Vincent Chen <vincent.chen@sifive.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmerdabbelt@google.com>,
        linux-riscv <linux-riscv@lists.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Oleg Nesterov <oleg@redhat.com>
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On Mon, Jun 1, 2020 at 4:15 PM Greentime Hu <greentime.hu@sifive.com> wrote=
:
>
> Guo Ren <guoren@kernel.org> =E6=96=BC 2020=E5=B9=B45=E6=9C=8831=E6=97=A5 =
=E9=80=B1=E6=97=A5 =E4=B8=8A=E5=8D=889:56=E5=AF=AB=E9=81=93=EF=BC=9A
> >
> > 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-cont=
rol-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>

--=20
Best Regards
 Guo Ren

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