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From:   Guo Ren <guoren@kernel.org>
Date:   Wed, 23 Dec 2020 22:57:37 +0800
Message-ID: <CAJF2gTTeqm7=NaUzSQ8NfJwvo8hNrHtkLx7rwyZE5FdmLL7+tw@mail.gmail.com>
Subject: Re: [PATCH] csky: Fix a size determination in gpr_get()
To:     Zhenzhong Duan <zhenzhong.duan@gmail.com>
Cc:     Al Viro <viro@zeniv.linux.org.uk>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-csky@vger.kernel.org, Oleg Nesterov <oleg@redhat.com>
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Hi Zhengzhong,

I'll take it, thx.

On Wed, Dec 23, 2020 at 10:31 AM Zhenzhong Duan
<zhenzhong.duan@gmail.com> wrote:
>
> On Wed, Sep 23, 2020 at 12:52 PM Al Viro <viro@zeniv.linux.org.uk> wrote:
> >
> > On Wed, Sep 23, 2020 at 10:37:31AM +0800, Guo Ren wrote:
> >
> > > > What's going on there?  The mapping is really weird - assuming
> > > > you had v0..v31 in the first 32 elements of regs->vr[], you
> > > > end up with
> > > >
> > > > v0 v1 v2 v3 v2 v3 v6 v7 v4 v5 v10 v11 v6 v7 v14 v15
> > > > v8 v9 v18 v19 v10 v11 v22 v23 v12 v13 v26 v27 v14 v15 v30 v31
> > > >
> > > > in the beginning of the output.  Assuming it is the intended
> > > > behaviour, it's probably worth some comments...
> > > FPU & VDSP use the same regs. 32 FPU regs' width is 64b and 16 VDSP
> > > regs' width is 128b.
> > >
> > > vr[0], vr[1] =3D fp[0] & vr[0] vr[1], vr[2], vr[3] =3D vdsp reg[0]
> > > ...
> > > vr[60], vr[61] =3D fp[15] & vr[60] vr[61], vr[62], vr[63] =3D vdsp re=
g[15]
> > > vr[64], vr[65] =3D fp[16]
> > > vr[66], vr[67] =3D fp[17]
> > > ...
> > > vr[94], vr[95] =3D fp[31]
> > >
> > > Yeah, this is confusing and I'll add a comment later.
> >
> > Umm...  It would help if you described these 3 layouts:
> >         1) kernel-side with VDSP
> >         2) userland (identical to (1)?)
> >         3) kernel-side without VDSP
> > Still confused...
> >
> > PS: my apologies re commit message - I left a note to myself when doing
> > that series and then forgot about it ;-/
> >
> > Anyway, which tree should it go through?  In any case, that fix is
> > Acked-by: Al Viro <viro@zeniv.linux.org.uk>
> > and I can take it through vfs.git or you guys can pick in csky tree;
> > up to you.
>
> Hi Al, Guo
>
> Seems this patch is still pending=EF=BC=8C could you help check it=EF=BC=
=9FThanks
>
> Zhenzhong


--=20
Best Regards
 Guo Ren

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