Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.debian.kernel > #71502 > unrolled thread

Bug#822112: still applies to current kernels

Back to article view | Back to linux.debian.kernel

This discussion starts older than the indexed window; earlier articles aren't shown. The article labeled Started by below is the oldest one visible, not the original post.

Contents

  Bug#822112: still applies to current kernels Martin-Éric Racine <martin-eric.racine@iki.fi> - 2021-05-12 05:30 +0200
    Bug#822112: still applies to current kernels Ben Hutchings <ben@decadent.org.uk> - 2021-05-17 20:10 +0200
      Bug#822112: still applies to current kernels Ben Hutchings <ben@decadent.org.uk> - 2021-05-17 20:20 +0200
        Bug#822112: still applies to current kernels Martin-Éric Racine <martin-eric.racine@iki.fi> - 2021-05-17 20:50 +0200

#71502 — Bug#822112: still applies to current kernels

This still applies to current kernels.

The problem seems to be that kernels after version 3 implement a
memory protection scheme that prevents the framebuffer from being
accessed by both vesafb and X drivers. The Geode X driver does that.

Martin-Éric

[toc] | [next] | [standalone]

#71685

[Multipart message — attachments visible in raw view] — view raw

Control: tag -1 wontfix

On Wed, 2021-05-12 at 06:16 +0300, Martin-Éric Racine wrote:
> This still applies to current kernels.
> 
> The problem seems to be that kernels after version 3 implement a
> memory protection scheme that prevents the framebuffer from being
> accessed by both vesafb and X drivers. The Geode X driver does that.

Then this is not a kernel bug.  The change was intentional and
documented in the NEWS file along with the option to revert it:

    - On most architectures, the /dev/mem device can no longer be used to
      access devices that also have a kernel driver.  This breaks dosemu
      and some old user-space graphics drivers.  To allow this, set the
      kernel parameter: iomem=relaxed

Ben.

-- 
Ben Hutchings
Never attribute to conspiracy what can adequately be explained
by stupidity.

[toc] | [prev] | [next] | [standalone]

#71686

[Multipart message — attachments visible in raw view] — view raw

On Mon, 2021-05-17 at 20:01 +0200, Ben Hutchings wrote:
> Control: tag -1 wontfix
> 
> On Wed, 2021-05-12 at 06:16 +0300, Martin-Éric Racine wrote:
> > This still applies to current kernels.
> > 
> > The problem seems to be that kernels after version 3 implement a
> > memory protection scheme that prevents the framebuffer from being
> > accessed by both vesafb and X drivers. The Geode X driver does that.
> 
> Then this is not a kernel bug.  The change was intentional and
> documented in the NEWS file along with the option to revert it:
> 
>     - On most architectures, the /dev/mem device can no longer be used to
>       access devices that also have a kernel driver.  This breaks dosemu
>       and some old user-space graphics drivers.  To allow this, set the
>       kernel parameter: iomem=relaxed

That said, this was originally reported before that change was made, so
possibly there are two different issues here.  Let us know if the
kernel parameter change doesn't allow the X driver to work again.

Ben.

-- 
Ben Hutchings
Never attribute to conspiracy what can adequately be explained
by stupidity.

[toc] | [prev] | [next] | [standalone]

#71688

ma 17. toukok. 2021 klo 21.13 Ben Hutchings (ben@decadent.org.uk) kirjoitti:
>
> On Mon, 2021-05-17 at 20:01 +0200, Ben Hutchings wrote:
> > Control: tag -1 wontfix
> >
> > On Wed, 2021-05-12 at 06:16 +0300, Martin-Éric Racine wrote:
> > > This still applies to current kernels.
> > >
> > > The problem seems to be that kernels after version 3 implement a
> > > memory protection scheme that prevents the framebuffer from being
> > > accessed by both vesafb and X drivers. The Geode X driver does that.
> >
> > Then this is not a kernel bug.  The change was intentional and
> > documented in the NEWS file along with the option to revert it:
> >
> >     - On most architectures, the /dev/mem device can no longer be used to
> >       access devices that also have a kernel driver.  This breaks dosemu
> >       and some old user-space graphics drivers.  To allow this, set the
> >       kernel parameter: iomem=relaxed
>
> That said, this was originally reported before that change was made, so
> possibly there are two different issues here.  Let us know if the
> kernel parameter change doesn't allow the X driver to work again.

Using this cmdline parameter indeed restores X driver operation. Feel
free to reassign.

I'll prepare a small patch to the Geode driver's own README to mention
this and upload the result to unstable.

Thanks for pointing out the fix.

Cheers!
Martin-Éric

[toc] | [prev] | [standalone]

Back to top | Article view | linux.debian.kernel

csiph-web