What is "nomodeset" SUPPOSED to do?

[Steven P. Ulrick]

Hello Everyone,
What is "nomodeset" SUPPOSED to do?  I really do want to know, because I wonder

if "nomodeset" is ineffectual on my system, and that's why I can't get
the 
rpmfusion nVidia driver to work (it used to work on this same system under 
Fedora 12.)

I want to go with the nVidia driver because:
1. nouveau (in KDE) leaves me with a hideous multicolored (grey & black) taskbar 
at the bottom of my display.
2. Whatever driver is defaulted to when nouveau won't run (vesa?) will boot 
perfectly on my system, BUT it only displays at a maximum resolution of 
1280x1024.  1920x1080 is the resolution I was running it at with this same 
system, same monitor, same video card on Fedora 12.

So, I'd really like to know if my problem is because "nomodeset" is doing 
nothing on my system...

Steven P. Ulrick

[Suvayu Ali]

On Monday 31 May 2010 06:30 PM, Tom Horsley wrote:
>  On Mon, 31 May 2010 20:04:53 -0500
>  Steven P. Ulrick wrote:
>
> > What is "nomodeset" SUPPOSED to do?
>
>  The newest kernels have (God knows why) moved the video
>  mode setting into the kernel (the only explanation I've
>  ever seen for why this is a good idea is that the monitor
>  goes "click" less often that way). 
There is a very compelling reason for this and progress is already being 
made in that direction. :)

http://lists.fedoraproject.org/pipermail/users/2010-May/372377.html

-- 
Suvayu

Open source is the future. It sets us free.

[Patrick O'Callaghan]

On Tue, 2010-06-01 at 08:01 -0400, Tom Horsley wrote:
>  On Tue, 1 Jun 2010 04:18:08 -0700
>  Mike Fedyk wrote:
>  
>  > > The newest kernels have (God knows why) moved the video
>  > > mode setting into the kernel (the only explanation I've
>  > > ever seen for why this is a good idea is that the monitor
>  > > goes "click" less often that way). So all the programming
>  > > of the hardware specific clock rates and registers on the
>  > > video card happen in the kernel during initial boot  
>  > 
>  > http://lwn.net/Articles/268378/
>  > 
>  > http://lwn.net/Articles/316274/
>  
>  Actually, there is one really excellent side-effect of kernel
>  mode setting: The ability to manually override the EDID info
>  with a kernel boot parameter (figuring out how to use it might
>  be a different problem :-). This will finally be a single point
>  where you can lock down a monitor's video setting so the system
>  will boot right even when the monitor isn't currently connected
>  via the KVM switch or the monitor itself reports bogus EDID
>  info. 
Actually for me the significant "side-effect" (I'd rather call it a
consequence) is the promise of being able to avoid user lockout if for
some reason the X server freezes. Not sure we're there yet, but in
principle it's possible.

poc

[Tom Horsley]

On Tue, 1 Jun 2010 04:18:08 -0700
Mike Fedyk wrote:

>  > The newest kernels have (God knows why) moved the video
>  > mode setting into the kernel (the only explanation I've
>  > ever seen for why this is a good idea is that the monitor
>  > goes "click" less often that way). So all the programming
>  > of the hardware specific clock rates and registers on the
>  > video card happen in the kernel during initial boot  
>  
>  http://lwn.net/Articles/268378/
>  
>  http://lwn.net/Articles/316274/ 
Actually, there is one really excellent side-effect of kernel
mode setting: The ability to manually override the EDID info
with a kernel boot parameter (figuring out how to use it might
be a different problem :-). This will finally be a single point
where you can lock down a monitor's video setting so the system
will boot right even when the monitor isn't currently connected
via the KVM switch or the monitor itself reports bogus EDID
info.

[Mike Fedyk]

On Mon, May 31, 2010 at 6:30 PM, Tom Horsley <horsley1953(a)gmail.com&gt; wrote:
>  On Mon, 31 May 2010 20:04:53 -0500
>  Steven P. Ulrick wrote:
>
> > What is "nomodeset" SUPPOSED to do?
>
>  The newest kernels have (God knows why) moved the video
>  mode setting into the kernel (the only explanation I've
>  ever seen for why this is a good idea is that the monitor
>  goes "click" less often that way). So all the programming
>  of the hardware specific clock rates and registers on the
>  video card happen in the kernel during initial boot 
http://lwn.net/Articles/268378/

http://lwn.net/Articles/316274/

For a better understanding, you'll want to read both articles above.
--
(And consider paying for a subscription to LWN.  It is one of the best
sources of news in the Linux community.)

[Kevin Fenzi]

On Mon, 31 May 2010 20:04:53 -0500
"Steven P. Ulrick" <lists-fedora(a)afolkey2.net&gt; wrote:

>  Hello Everyone,
>  What is "nomodeset" SUPPOSED to do?  I really do want to know,
>  because I wonder if "nomodeset" is ineffectual on my system, and
>  that's why I can't get the rpmfusion nVidia driver to work (it used
>  to work on this same system under Fedora 12.) 
Is your current system Fedora 13? 

If so, then yes, 'nomodeset' doesn't do anything, as the nouveau driver
in f13 has no userspace modesetting ability. :) 

>  I want to go with the nVidia driver because:
>  1. nouveau (in KDE) leaves me with a hideous multicolored (grey &
>  black) taskbar at the bottom of my display. 
:( 

Have you reported a bug on it? 
See also https://fedoraproject.org/wiki/Xorg/Debugging

>  2. Whatever driver is defaulted to when nouveau won't run
> (vesa?)
>  will boot perfectly on my system, BUT it only displays at a maximum
>  resolution of 1280x1024.  1920x1080 is the resolution I was running
>  it at with this same system, same monitor, same video card on Fedora
>  12. 
Yes, that would be vesa. 

>  So, I'd really like to know if my problem is because
> "nomodeset" is
>  doing nothing on my system... 
well, sure, but I would rather say it's a bug in nouveau that it
doesn't work correctly for your card. 

Do you have mesa-dri-drivers-experimental installed?

kevin

[Tom Horsley]

On Mon, 31 May 2010 20:04:53 -0500
Steven P. Ulrick wrote:

>  What is "nomodeset" SUPPOSED to do? 
The newest kernels have (God knows why) moved the video
mode setting into the kernel (the only explanation I've
ever seen for why this is a good idea is that the monitor
goes "click" less often that way). So all the programming
of the hardware specific clock rates and registers on the
video card happen in the kernel during initial boot
rather than in the X driver when the X server starts.
(And the X driver developers hate having to deal with
both possibilities, so they'd really like no one to ever
use nomodeset).

The "nomodeset" kernel parameter turns off this feature
and leaves the system BIOS video setting in place during
boot.

Because the kernel may need the video driver loaded to
do mode setting, the nouveau driver is probably included
in the initrd image, hence the need for both "nomodeset"
and "rdblacklist=nouveau" to keep the kernel out of the
video mode business so the binary nvidia driver can
then do mode setting when X starts with no conflicting
drivers loaded in the kernel.

That, at least, is my summary of the obscure bits of
information I've absorbed over time (maybe incorrectly)
about this mode setting issue.