linux-kernel - Re: [RFC PATCH v4 00/13] riscv: Add vector ISA support

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Date:   Tue, 2 Jun 2020 11:08:14 +0800
From:   Guo Ren <guoren@...nel.org>
To:     Greentime Hu <greentime.hu@...ive.com>
Cc:     Guo Ren <guoren@...ux.alibaba.com>,
        Vincent Chen <vincent.chen@...ive.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmerdabbelt@...gle.com>,
        linux-riscv <linux-riscv@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Oleg Nesterov <oleg@...hat.com>
Subject: Re: [RFC PATCH v4 00/13] riscv: Add vector ISA support

On Tue, Jun 2, 2020 at 10:21 AM Greentime Hu <greentime.hu@...ive.com> wrote:
>
> Guo Ren <guoren@...nel.org> 於 2020年5月31日 週日 下午11:52寫道：
> >
> > Hi Greentime & Vincent,
> >
> > Thx for the dynamic vlen implementation. I've two suggestions:
> >  - Please give out glibc patches mail URL, we need to review them together.
> >  - We need to consider that not all processes need vectors. Most
> > system processes do not have vector features, and we should not force
> > save/restore vector for every process.
> >
>
> Hi Guo,
>
> Thanks for reviewing the patch. We are still cooking the glibc patch,
> we will add the glibc link address once we post it.
> For the save/restore mechanism in signal, it is basically the same
> with FPU porting, we can optimize it when setup_sigcontext() for both
> FPU and VECTOR in the future.
>
> /* Save the floating-point state. */
> if (has_fpu)
>         err |= save_fp_state(regs, &sc->sc_fpregs);
> /* Save the vector state. */
> if (has_vector)
>         err |= save_v_state(regs, sc);
>
> There should be a better way to detect whether this task use
> fpu/vector or not. Might be elf attributes or something else.
Ok, we could improve it in future patches.

-- 
Best Regards
 Guo Ren

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