Re: [PATCH v4 1/2] selftests: run tests on nommu architecture

[Hajime Tazaki <thehajime@gmail.com>]

Hello,

On Fri, 02 Oct 2026 21:21:53 +0900,
David Hildenbrand (Arm) wrote:
> 
> On 10/2/26 13:53, Lorenzo Stoakes (ARM) wrote:
> > On Fri, Oct 02, 2026 at 01:38:31PM +0200, Geert Uytterhoeven wrote:
> > 
> >> On Fri, 2 Oct 2026 at 10:10, Lorenzo Stoakes (ARM) <ljs@kernel.org> wrote:
> > 
> >>> But fork() -> -EINVAL or -ENOSYS = nommu, then just have the child quit and
> >>> etc. should do it.
> >>
> >> fork() is not strictly an MMU-feature (you can implement fork on nommu
> >> if all memory accesses are done relative to a base address register),
> >> while I think mprotect() is an MMU-feature. Unless it can also be used
> >> to change the protection using the one or two BARs most MCU haves?
> >> Anything else that is a real MMU-feature? Non-identity mmap()?
> > 
> > Does any nommu arch implement fork() in linux?
> 
> I was about to say, that sounds a bit too theoretical for me. IIUC that is not
> implemented, and if someone would propose it we would likely just nak it.
> 
> In the unlikely event that this would see the light of day, we could always
> change our detection in the selftests.

thanks all for the inputs and review.

I will try to implement the detection with /proc/meminfo.

-- Hajime