[U-Boot] [Patch v4 2/5] ARMv8: Adjust MMU setup

Rob Herring
2014-06-06T13:34:01Z

On Thu, Jun 5, 2014 at 1:34 PM, York Sun <yorksun@freescale.com> wrote:
> On 06/05/2014 10:41 AM, Mark Rutland wrote:
>> On Thu, Jun 05, 2014 at 04:07:17PM +0100, York Sun wrote:
>>> On 06/05/2014 03:09 AM, Mark Rutland wrote:

[...]

>>> No objection here on the idea. But again this is not the case. My first MMU
>>> table is in SRAM, which is small and will be used for other purpose. The 2nd MMU
>>> table is in DDR. I could copy the table and do the maintenance as you said. For
>>> now, I want to stick with the static table and only create the API when I have to.
>>
>> Sure, if your tables are in SRAM then trying to do a load of dynamic
>> allocation isn't going to work.

Why do you need to turn on the MMU early using SRAM in the first
place? Can't you delay that until after DDR setup?

>> My fear is that while that sounds OK with a single user to do a quick
>> havk and poke the tables directly, we'll end up with everyone doing
>> that, and no-one will try to unify things. It is very diffifcult to
>> unify such variation after the fact.
>
> That's a good reason. Let me start to code the API. It will take a while to
> cover the complexity of the multilevel tables and sizes. It will be a separated
> patch for later review. I don't want that to delay this patch set. I am hoping
> to get this set in for 2014.07 release.

If I was maintainer I would say no because few people come back later
to clean-up their mess. If you want to get platform support in now,
perhaps you should just add the base platform first and add mmu setup
later. Surely you don't need the MMU to just boot to u-boot shell.

Rob