# What is kernel mode setting useful for?

## gw

I recently switched to nouveau and I can now. from within X, switch to a console via CTRL-ALT-F*.

Yet I fail to see a scenario, where this would be actually useful: when would I do that and no simply open another terminal under X?

Thanks for your hints.

gw

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## aCOSwt

Running an X terminal as root is strongly discouraged.

=> I switch to console whenever I need to do something as root.

BTW, I do not formally call this facility of switching to console kernel mode setting.

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## Gusar

The console is just one user of KMS, not what KMS is all about.

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## py-ro

And Switchign via ALT-F1 works without KMS...

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## cach0rr0

 *gw wrote:*   

> I recently switched to nouveau and I can now. from within X, switch to a console via CTRL-ALT-F*.
> 
> Yet I fail to see a scenario, where this would be actually useful: when would I do that and no simply open another terminal under X?
> 
> Thanks for your hints.
> ...

 

a)you were able to CTRL+ALT+F* long before KMS. KMS just makes it a bit "prettier" and swifter

b)you can also do e.g. CTRL+ALT+F* to switch to a different X session, as you could have before

c)ever have a problem in X where the mouse becomes unresponsive, and you desperately need to do something that can only be fixed from the CLI?

those are just the quickest points that come to mind; there are others.

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## Aquous

Some advantages of KMS:

 - a flicker-free boot process

 - the system drops to console mode when a panic occurs instead of just freezing

 - no need to run X as root (X no longer needs direct control over your card)

 - VTs at your monitor's native resolution - so no flicker when switching VTs

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## depontius

 *Aquous wrote:*   

> Some advantages of KMS:
> 
> ...
> 
>  - no need to run X as root (X no longer needs direct control over your card)
> ...

 

I don't think we're quite there yet...

```
root      3727     1  0 06:40 ?        00:00:00 /usr/bin/gdm

root      3730  3727  0 06:40 ?        00:00:00 /usr/bin/gdm

root      3732  3730  0 06:40 tty7     00:00:19 /usr/bin/X :0 -audit 0 -auth /var/gdm/:0.Xauth vt7

...

gdm       3763  3730  0 06:40 ?        00:00:24 /usr/libexec/gdmgreeter
```

One of these days, but not today.  This is with the "radeon" driver, not any of the closed binaries.

EDIT

I guess by "we" I mean the mix of mostly stable and a little ~arch that I'm running, one of those ~arch things being xorg-server-1.11.0.  Do you know of any other distributions running rootless X?

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## VoidMage

Well, the above is cause:

```
ls -l /usr/bin/Xorg

-rws--x--x 1 root root 1745004 08-27 07:52 /usr/bin/Xorg
```

Though I'm not sure about non-root xserver for a different reason - libudev might require it for listening for events.

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## Gusar

It's not libudev directly, but it is stuff regarding input handling why X still needs to be run as root. And possibly a few other things as well. I think there's even a simple document out there that briefly lists what still needs to be done. KMS is just one piece of the puzzle that will make an X without root possible.

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## VoidMage

I actually meant libudev indirectly - never really read into the problem, but it's something about needing root to listen on that kernel socket.

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## cabotp

 *cach0rr0 wrote:*   

> 
> 
> a)you were able to CTRL+ALT+F* long before KMS. KMS just makes it a bit "prettier" and swifter
> 
> b)you can also do e.g. CTRL+ALT+F* to switch to a different X session, as you could have before
> ...

 

We have a winner  :Smile: 

I don't know how many times I've had a problem with X and without being able to CTRL-ALT+F*.  I probably would have taken the computer and chucked it across the room.

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## dmpogo

 *gw wrote:*   

> I recently switched to nouveau and I can now. from within X, switch to a console via CTRL-ALT-F*.
> 
> Yet I fail to see a scenario, where this would be actually useful: when would I do that and no simply open another terminal under X?
> 
> Thanks for your hints.
> ...

 

when your KDE or whatever window manager freezes, you thank for the opportunity of Alt-Cntrl-F*   :Smile:    Which is of course separate and existed long before KMS

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