Re: [PATCH v3 2/5] build: Hook the schedulers into Kconfig

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Fri, Jan 08, 2016 at 11:04:56AM -0600, Jonathan Creekmore wrote:
> 
> Doug Goldstein writes:
> 
> > On 1/8/16 10:49 AM, Jan Beulich wrote:
> >>>>> On 08.01.16 at 17:30, <jonathan.creekmore@gmail.com> wrote:
> >>> So, based on the Kconfig setup and the linker ASSERT, there should be no
> >>> way to have a default scheduler that is not in the build. I wish Kconfig
> >>> allowed you to state that you must have at least one option selected or
> >>> up to all of the options selected (so I could require 1-4 schedulers
> >>> compiled in, but not 0). Unfortunately, the only way that seems allowed
> >>> is if you compile code in as modules, which Xen does not (with a choice
> >>> block, you can select multiple items as M, but only 1 as Y, but at least
> >>> 1 must be present --- since we only support Y, the choice block wouldn't
> >>> work for the schedulers).
> >>
> >> Perhaps credit should just not be configurable then?
> >>
> >> Jan
> >>
> >
> > How much effort are we willing to put in saving someone? We've already
> > got these options completely hidden away. We've already given the user a
> > warning that what they're doing isn't supported and they shouldn't be
> > touching this. Then they have to disable the scheduler that they pick as
> > the default. How many people are we expecting to really do this? I'm all
> > for idiot proofing things but at some point we've got to say there's
> > enough barriers to prevent this from happening. Otherwise we need to put
> > a Xen developer in every Xen users home or office.
> 
> At this point, with the (not submitted yet) ASSERT in the linker file,
> it is a compile error to not have any schedulers linked in and Kconfig
> enforces that only schedulers compiled in can be a default.

That would be good!