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From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Christoph Hellwig <hch@lst.de>
Cc: Greg Ungerer <gerg@linux-m68k.org>,
	linux-m68k <linux-m68k@lists.linux-m68k.org>,
	uClinux development list <uclinux-dev@uclinux.org>,
	Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH] m68knommu: remove set_fs()
Date: Mon, 5 Jul 2021 13:33:39 +0200	[thread overview]
Message-ID: <CAMuHMdXB1aYK+jUtkf0L5UCNt2HCH53gxY2rDxYHCNFVSG91yw@mail.gmail.com> (raw)
In-Reply-To: <20210705085607.GA6827@lst.de>

Hi Christoph,

On Mon, Jul 5, 2021 at 10:56 AM Christoph Hellwig <hch@lst.de> wrote:
> On Mon, Jul 05, 2021 at 10:44:51AM +0200, Geert Uytterhoeven wrote:
> > > --- a/arch/m68k/Kconfig
> > > +++ b/arch/m68k/Kconfig
> > > @@ -32,7 +32,7 @@ config M68K
> > >         select NO_DMA if !MMU && !COLDFIRE
> > >         select OLD_SIGACTION
> > >         select OLD_SIGSUSPEND3
> > > -       select SET_FS
> > > +       select SET_FS if MMU
> >
> > Probably this should be
> >
> >     select SET_FS if CPU_HAS_ADDRESS_SPACES
> >
> > instead.  Classic m68k (except for good old 68000) has address spaces,
> > Coldfire has not.
>
> No, at least not yet.  Coldfire and co still rely on set_fs for various
> things in the m68k arch code, and also don't provide
> __{get,put}_kernel_nofault yet.  So wile m68k with CPU_HAS_ADDRESS_SPACES
> will probably one of the hardest ports to get rid of set_fs() for,
> m68k/mmu without CPU_HAS_ADDRESS_SPACES would be a logical next step.
> I could try to whiteboard code some of it, but I'd need help from dedicated

M68k/mmu with CPU_HAS_ADDRESS_SPACES needs to use the address spaces
to access user space from kernel space using the "moves" instruction.
Coldfire doesn't.

See arch/m68k/include/asm/uaccess.h.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

  reply	other threads:[~2021-07-05 11:33 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-05  5:57 RFC: stop implementing set_fs for m68knommu Christoph Hellwig
2021-07-05  5:57 ` [PATCH] m68knommu: remove set_fs() Christoph Hellwig
2021-07-05  8:44   ` Geert Uytterhoeven
2021-07-05  8:56     ` Christoph Hellwig
2021-07-05 11:33       ` Geert Uytterhoeven [this message]
2021-07-05 11:51         ` Christoph Hellwig
2021-07-05 20:39     ` Linus Torvalds
2021-07-06  4:13       ` Christoph Hellwig
2021-07-06 18:36         ` Linus Torvalds
2021-07-07 14:25           ` Christoph Hellwig
2021-07-07 17:41             ` Linus Torvalds
2021-07-08  1:39             ` Michael Schmitz
2021-07-08  3:40       ` Michael Schmitz
2021-07-08  4:14         ` Linus Torvalds
2021-07-08  4:17           ` Christoph Hellwig
2021-07-08  6:33           ` Michael Schmitz

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