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Re: Activate/deactivate kernel parameters without reboot




	Hi.

On Fri, Mar 30, 2018 at 11:50:46AM +0200, tomas@xxxxxxxxxx wrote:
> On Fri, Mar 30, 2018 at 04:50:06AM -0300, rv riveravaldez wrote:
> > On Thu, Mar 29, 2018 at 11:28 PM, Stefan Monnier
> > <monnier@xxxxxxxxxxxxxxxx> wrote:
> > >> I'm running with a 'nouveau.noaccel=1' kernel parameter added at hand
> > > [...]
> > >> Is there any way to deactivate and reactivate such a parameter without
> > >> the need to reboot?
> > >
> > > You can try and change it with
> > >
> > >     # echo 0 > /sys/modules/<MODULENAME>/parameters/noaccel
> > >
> > >
> > > -- Stefan
> > 
> > Hi, thanks a lot.
> > 
> > I tried it in both situations with same result.
> > 
> > Deactivate:
> > 
> > # cat /sys/module/nouveau/parameters/noaccel
> > 1
> > # echo 0 > /sys/module/nouveau/parameters/noaccel
> > bash: /sys/module/nouveau/parameters/noaccel: Permiso denegado
> > 
> > Activate:
> > 
> > # cat /sys/module/nouveau/parameters/noaccel
> > 0
> > # echo 1 > /sys/module/nouveau/parameters/noaccel
> > bash: /sys/module/nouveau/parameters/noaccel: Permiso denegado
> > 
> > 
> > 'Permiso denegado' means 'Permission denied'.
> > 
> > 
> > What else shoud/could I do?
> 
> You have to be root to change those things. Try
> 
>   sudo bash -c "echo 0 > /sys/module/nouveau/parameters/noaccel"
> 
> It will ask you for your password.

It won't do any good, because:

# ls -al /sys/module/nouveau/parameters/noaccel
-r-------- 1 root root 4096 Mar 30 14:37 /sys/module/nouveau/parameters/noaccel

Permissions of '400' in these case mean that its impossible to change
this module parameter via /sys (and changing them to 600 won't work
either). So, to answer the original question - yes, the reboot is required.

Reco