Re: [PATCH] arch/x86/xen: remove depends on CONFIG_EXPERIMENTAL

From: Greg Kroah-Hartman
Date: Mon Feb 25 2013 - 09:36:45 EST

On Mon, Feb 25, 2013 at 12:39:27PM +0000, Stefano Stabellini wrote:
> On Sun, 24 Feb 2013, Greg Kroah-Hartman wrote:
> >
> > You should not have unstable options in the kernel in the first place,
> > sorry.
> With the premise that the removal of CONFIG_EXPERIMENTAL is not an issue
> for me personally or my work, I am going to give you my 2 cents on the
> matter, but feel free to ignore them :)
> While I understand that CONFIG_EXPERIMENTAL has been abused, I feel that
> rejecting everything that is not fully stable and with external
> interfaces set in stones, might hinder the development of new features.

It's been this way for _years_ this isn't something new (the "you have
to get it right really quickly" problem). See Documentation/ABI/ for
some words about how you can try to do this.

> After all, given how fast the kernel is moving nowadays,

No faster than it has in the past.

> maintaining a project out-of-tree until is completely ready for
> production can be very expensive. Merging the project earlier and
> completing the development upstream can bring better results.

Yes, but don't go changing user-visable apis when you do so. That's
been a hard rule for a LONG time.

> But in these cases one wouldn't want to "market" the feature as stable
> yet, because it just isn't. If CONFIG_EXPERIMENTAL is going away, is
> there anything in the kernel that can be used to tag a feature as "I
> wouldn't use it in production if I were you"? Maybe just a comment in
> the kconfig description?

I know this is hard, I've had my own problems with it in the past. You
don't know if you get an api right until you have a lot of users. See
our previous "discussions" about this topic on lkml if you are curious
as to the eventual outcome of threads like this:

Yes, it's hard, but that's kernel programming.


greg k-h
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