Re: [PATCH v2 2/2] ARM: mm: convert empty_zero_page to array for consistency

[Giulio Benetti]

Hello Russell,

On 19/10/22 16:44, Russell King (Oracle) wrote:
> On Wed, Oct 19, 2022 at 12:25:03AM +0200, Giulio Benetti wrote:
> > ARM architecture is the only one to have empty_zero_page to be a
> > struct page pointer, while in all other implementations empty_zero_page is
> > a data pointer or directly an array(the zero page itself). So let's convert
> > empty_zero_page to an array for consistency and to avoid an early
> > allocation+dcache flush. Being the array in .bss it will be cleared earlier
> > in a more linear way(and a bit faster) way.
> >
> > Suggested-by: Arnd Bergmann <arnd@xxxxxxxx>
> > Signed-off-by: Giulio Benetti <giulio.benetti@xxxxxxxxxxxxxxxxxxxxxx>
>
> I'm completely against this approach. It introduces inefficiencies in
> paths we don't need, and also means that the zero page is at a fixed
> location relative to the kernel, neither of which I like in the
> slightest.

I haven't considered those details, I'm pretty new in this topic.
I was thinking with a no-mmu approach in my mind, that's why the
.bss approach. And also the exposure of the entire array to the other
subsystem is not a good idea.

Thank you for pointing me

Best regads
--
Giulio Benetti
CEO/CTO@Benetti Engineering sas