Arches that don't support PREEMPT

[Anton Ivanov]

On 19/09/2023 16:17, Thomas Gleixner wrote:
> On Tue, Sep 19 2023 at 15:21, Anton Ivanov wrote:
>> On 19/09/2023 14:42, Peter Zijlstra wrote:
>>> 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.
> What's so difficult about it?

It's been a while. I remember that I dropped it at the time, but do not remember the full details.

There was some stuff related to FP state and a few other issues I ran into while rewriting the interrupt controller. Some of it may be resolved by now as we are using host cpu flags, etc.

I can give it another go :)

>
> Thanks,
>
>          tglx
>
-- 
Anton R. Ivanov
Cambridgegreys Limited. Registered in England. Company Number 10273661
https://www.cambridgegreys.com/