Arches that don't support PREEMPT

[Matthew Wilcox]

On Tue, Sep 19, 2023 at 02:30:59PM +0200, Thomas Gleixner wrote:
> Though it just occured to me that there are dragons lurking:
> 
> arch/alpha/Kconfig:     select ARCH_NO_PREEMPT
> arch/hexagon/Kconfig:   select ARCH_NO_PREEMPT
> arch/m68k/Kconfig:      select ARCH_NO_PREEMPT if !COLDFIRE
> arch/um/Kconfig:        select ARCH_NO_PREEMPT

Sounds like three-and-a-half architectures which could be queued up for
removal right behind ia64 ...

I suspect none of these architecture maintainers have any idea there's a
problem.  Look at commit 87a4c375995e and the discussion in
https://lore.kernel.org/lkml/20180724175646.3621-1-hch@lst.de/

Let's cc those maintainers so they can remove this and fix whatever
breaks.