Re: Selecting MMU page size for an architecture

[Sergey Organov]

Hi Jon,

Jon Masters <jcm@xxxxxxxxxxxxxx> writes:

> Hey Sergey,
>
> On Thu, Dec 23, 2021 at 8:15 AM Sergey Organov <sorganov@xxxxxxxxx> wrote:
>
>> We are building custom CPU and have an option to choose either 4K or 16K
>> MMU minimum page size that will then be fixed in the hardware. For
>> reasons unrelated to the Linux kernel we'd prefer 16K, but I have some
>> doubts.
>>
>> What pros and cons for kernel and user-space operation 16K pages will
>> have over more usual 4K pages? Anything we should worry about?
>
> If you want maximum compatibility with existing source written for
> industry at large (e.g. x86/Arm) and even the assumptions in other
> devices (and their firmware) you might connect (PCI, or even on-SoC)
> then you'll want to go with 4K. However, if I were designing a brand
> new architecture today and didn't care about legacy, I would
> definitely consider following Apple into 16K.

I don't think we will have issues with device drivers because of this,
but even if so, I believe we'll be able to fix that, so I get your
advice as +1 in favor of 16K pages.

Thanks for sharing!

-- Sergey Organov