Bug#822112: still applies to current kernels

From	Martin-Éric Racine <martin-eric.racine@iki.fi>
Newsgroups	linux.debian.bugs.dist, linux.debian.kernel
Subject	Bug#822112: still applies to current kernels
Date	2021-05-17 20:50 +0200
Message-ID	<CfQts-1K9-11@gated-at.bofh.it> (permalink)
References	(1 earlier) <CdNJo-uu-1@gated-at.bofh.it> <CfPQJ-1xf-11@gated-at.bofh.it> <CfQ0p-1Aq-5@gated-at.bofh.it> <rqkbE-7J8-5@gated-at.bofh.it> <CfQ0p-1Aq-5@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Cross-posted to 2 groups.

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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

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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

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