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Re: ID problem: "the nouveau driver"

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debian-user@howorth.org.uk composed on 2023-03-24 11:02 (UTC):

> Felix Miata <mrmazda@earthlink.net> wrote:

>> <https://www.linuxquestions.org/questions/blog/mrmazda-1035595/amd-intel-and-nvidia-x-graphics-driver-primer-38306/>

> "You are not logged in or you do not have permission to access this
> page."

> ?? why should I need an account to see this page?

You would have to login and ask the webmaster. :( I've submitted your question to
one of its admins.

This is its content, last updated 2021-09-14
[quote]
"Drivers" for the subject brands of GPUs for X, whether Wayland or Xorg, consist
of multiple components or layers. This primer discusses only the first two layers,
and only for the FOSS types included in the installation media for most GNU Linux
distributions and their standard FOSS repositories.

First layer is the kernel. Each kernel comes with one or more of its own modules
for each brand of GPU. For AMD, there is amdgpu for current and recent
GPUs/APUs/IGPs, and radeon for older. For Intel there is gma500 for many SOC
configurations, and i915 for the rest. For NVidia there is only nouveau. These
kernel modules provide Kernel ModeSetting (KMS) functionality that the
foundational X driver layer unconditionally depends upon.

These foundational X drivers are traditionally hardware device dependent, and thus
are called DDX, for device dependent X (driver). Again, for AMD there is amdgpu
for current and radeon for older; for Intel there is only intel; and for NVidia
there is only nouveau. Each of these is provided by an upstream optional
xf86-video-* source package. However, there is a newer technology device
independent X driver, now more than six years old, that functions as if it was
device dependent, but which is in fact created for supporting AMD, Intel, NVidia
(and others), not surprisingly, called modesetting. This modesetting DIX is
provided by the X server source package rather than a separate one, so is not
optional, unlike the xf86-video-* packages. Because it is relatively new, older
GPUs (roughly prior to Gen4 for Intel, or 2007 or 2008 for others) are not
supported by it.

Even though upstream modesetting is the default X driver, and the xf86-video-*
packages are technically optional, most Linux installations include a metapackage
that installs every one of the xf86-video-* packages. This metapackage causes
older GPUs unsupported by the modesetting DIX to be supported by a default
installation, which in effect in many cases preempts the upstream default
modesetting DIX that supports most non-ancient GPUs that are not too new for
standard support.

Because of the prevalence of this preemptive override, most people speaking of
video "drivers" don't even know the modesetting DIX exists. And because of the
similar naming for kernel modules and DDXes, discussion of graphics "drivers" is
often lacking clarity. This is particularly true for those for NVidia GPUs.
Discussion of kernel driver is often intended when technically speaking of a DDX
or DIX, and vice versa.

Those who wish to employ the modesetting DIX can most easily do so by uninstalling
the video DDX metapackage and whichever discrete video package is applicable to
the installed GPU(s). Whether the modesetting DIX will perform "better" than a
GPU-specific video package can only be determined by trying both and comparing
behavior. It is not unusual that tearing or other buggy behavior can be eliminated
or reduced by a switch between DDX and DIX or vice versa.

For X there is additionally a pair of limited functionality drivers that do not
depend on KMS that support AMD, Intel, NVidia and more. These are FBDEV and VESA.
These are unaccelerated, and support few, if any, modern widescreen resolutions,
typically limited to 4:3 modes 1280x1024, 1600x1200, or less, often only 1024x768.
Most find these acceptable only for rescue operations, or for servers where X is
in use little to none. Not infrequently it is one of these two that are required
for installation to proceed. When this happens, usually the bootloader on the
installed system is configured to include nomodeset on each of the linux lines.
The result of nomodeset in the bootloader is the competent DDX's and DIX's support
is precluded, making the user unhappy with graphics performance, or confronting
her with a black screen where a login greeter is expected until it is discovered
why and how to remove nomodeset from the boot process.

In summary, "drivers" required for competent X operation are:

    amdgpu (kernel) plus amdgpu (DDX) or modesetting (DIX) for current and
non-ancient AMD APUs/GPUs/IGPs
    radeon (kernel) plus modesetting (DIX) or radeon (DDX) for ancient AMD/ATI
GPUs/IGPs
    gma500 (kernel) or i915 (kernel) plus intel (DDX) or modesetting (DIX) for
Intel GPUs/IGPs
    nouveau (kernel) plus modesetting (DIX) or nouveau (DDX) for NVidia GPUs
[/quote]
-- 
Evolution as taught in public schools is, like religion,
	based on faith, not based on science.

 Team OS/2 ** Reg. Linux User #211409 ** a11y rocks!

Felix Miata

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Thread

nvidia package wrong documentation? Hans <hans.ullrich@loop.de> - 2023-03-22 11:00 +0100
  Re: nvidia package wrong documentation? David Wright <deblis@lionunicorn.co.uk> - 2023-03-22 15:50 +0100
  Re: nvidia package wrong documentation? Vincent Lefevre <vincent@vinc17.net> - 2023-03-23 14:50 +0100
    Re: ID problem: "the nouveau driver" (was: nvidia package wrong  documentation?) Felix Miata <mrmazda@earthlink.net> - 2023-03-23 18:40 +0100
      Re: ID problem: "the nouveau driver" (was: nvidia package wrong  documentation?) Vincent Lefevre <vincent@vinc17.net> - 2023-03-24 04:00 +0100
        Re: ID problem: "the nouveau driver" Felix Miata <mrmazda@earthlink.net> - 2023-03-24 04:50 +0100
          Re: ID problem: "the nouveau driver" debian-user@howorth.org.uk - 2023-03-24 12:10 +0100
            Re: ID problem: "the nouveau driver" Felix Miata <mrmazda@earthlink.net> - 2023-03-24 17:20 +0100
              Re: ID problem: "the nouveau driver" debian-user@howorth.org.uk - 2023-03-24 21:30 +0100

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