Re: Arches that don't support PREEMPT

[Anton Ivanov]

On 19/09/2023 14:42, Peter Zijlstra wrote:
> On Tue, Sep 19, 2023 at 03:37:24PM +0200, John Paul Adrian Glaubitz wrote:
> > On Tue, 2023-09-19 at 14:00 +0100, Matthew Wilcox wrote:
> > > 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 ...
> >
> > The agreement to kill off ia64 wasn't an invitation to kill off other stuff
> > that people are still working on! Can we please not do this?
>
> If you're working on one of them, then surely it's a simple matter of
> working on adding CONFIG_PREEMPT support :-)

In the case of UML adding preempt will be quite difficult. I looked at this a few years back.

At the same time it is used for kernel test and other stuff. It is not exactly abandonware on a CPU found in archaeological artifacts of past civilizations like ia64.

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Anton R. Ivanov
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