Re: [PATCH] vt: Add enable module parameter

[Jocelyn Falempe]

On 26/01/2026 15:36, Greg Kroah-Hartman wrote:
> On Mon, Jan 26, 2026 at 02:05:36PM +0100, Jocelyn Falempe wrote:
> > On 26/01/2026 13:46, Greg Kroah-Hartman wrote:
> > > On Mon, Jan 26, 2026 at 01:26:34PM +0100, Jocelyn Falempe wrote:
> > > > On 26/01/2026 11:59, Greg Kroah-Hartman wrote:
> > > > > On Mon, Jan 26, 2026 at 11:48:50AM +0100, Jocelyn Falempe wrote:
> > > > > > On 26/01/2026 11:20, Greg Kroah-Hartman wrote:
> > > > > > > On Mon, Jan 26, 2026 at 10:43:35AM +0100, Jocelyn Falempe wrote:
> > > > > > > > On 26/01/2026 10:33, Greg Kroah-Hartman wrote:
> > > > > > > > > On Mon, Jan 26, 2026 at 10:21:50AM +0100, Jocelyn Falempe wrote:
> > > > > > > > > > This allows to build the kernel with CONFIG_VT enabled, and choose
> > > > > > > > > > on the kernel command line to enable it or not.
> > > > > > > > >
> > > > > > > > > This says what is happening, but not why?
> > > > > > > > >
> > > > > > > > > > Add vt.enable=1 to force enable, or vt.enable=0 to force disable.
> > > > > > > > >
> > > > > > > > > Why are we using a 1990's technology for a new feature?  What is this
> > > > > > > > > going to allow to have happen?  Who needs/wants this?  Who will use it?
> > > > > > > > > For what?
> > > > > > > >
> > > > > > > > The goal is to ease the transition to disable CONFIG_VT.
> > > > > > > >
> > > > > > > > So if this is merged, you can boot without VT on any Linux distribution,
> > > > > > > > without rebuilding the kernel.
> > > > > > >
> > > > > > > But that's a distro-specific thing, the distro should be enabling or
> > > > > > > disabling the option as it needs, it should not be a user-configurable
> > > > > > > boot-time selection option as userspace depends entirely on this either
> > > > > > > being there or not.  Why would you have a kernel with both options but
> > > > > > > userspace without that?
> > > > > >
> > > > > > Actually the userspace side works with or without VT, at least with Fedora,
> > > > > > I've my Gnome session in both cases.
> > > > >
> > > > > Great!  Then why is this even needed?  Who wants such a "let's not make
> > > > > up our mind until we boot" type of system?
> > > > >
> > > > > Given that traditionally the command line is a "secure" thing, that is
> > > > > locked down by distros and orginizations, who would ever be able to be
> > > > > changing this type of thing?  Who would want to support userspace that
> > > > > handles both at the same time?
> > > > >
> > > > > I don't see the issue here, if a distro doesn't want to support VT, then
> > > > > disable it in the kernel and all is good.  If they do want to support
> > > > > it, than enable it.  Don't do both :)
> > > >
> > > > Maybe the real issue is that VT cannot be built as a module.
> > > > That way the userspace would be able to load it only if it needs it.
> > > >
> > > > That's probably more complex than my 3 lines patch, but I can try.
> > > > Would you prefer it that way?
> > >
> > > If that would make it simpler for a distro to handle this, perhaps.  Try
> > > it and see, I think the last time this came up, unwinding this into a
> > > module just wasn't possible, but that might have been a long time ago, I
> > > can't recall.
> > >
> > > But again, why wouldn't a distro pick a "this is what we are going to
> > > support" line and stick with it?  Why would they want to support both?
> >
> > It's all about the transition. Talks about VT-less system started in 2012,
> > but since then no major desktop Linux distribution have done it.
>
> Then perhaps it's not really ever going to happen if no one actually
> does the work and wants their distro to change to not have it.

To give some contexts, I proposed to switch to kmscon for Fedora 44, so 
once we are there, it will be feasible to switch off VT, in 1 or 2 
years. But the requirement to rebuild the kernel, makes it painful to 
test, and much harder to get accepted.

> > I think that one of the reason, is that if you switch off VT, of course some
> > users will complain, as it has a lot of implications.
>
> Again, that's a distro's policy decision to make, don't force the kernel
> to support a wishy-washy distro's decision :)

Agreed, I can also keep this patch as downstream, if you think it's 
better that way. But I though it may interest other distributions as well.

> > Telling them to go rebuild their kernel is not good.
>
> Agreed, this is a policy decision a distro needs to make.
>
> > Telling them to run
> > grubby to change the kernel command line until they find alternative for
> > their use case is better. They can experiment and do the switch when they
> > are ready.
> > Really it's nothing more than that.
>
> Again, policy decision that a distro needs to make.
>
> > I don't think a distribution will want to maintain VT and noVT for a long
> > time.
>
> Please define "long time" given that no distro has even done this yet?

I hope it won't get longer than 1 or 2 year.

> thanks,
>
> greg k-h