On Fri, Jun 06, 2014 at 07:52:44AM -0700, York Sun wrote: > On 06/06/2014 06:34 AM, Rob Herring wrote: > > On Thu, Jun 5, 2014 at 1:34 PM, York Sun <york...@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? > > Logically yes. But it runs too slow without cache on emulator. > > > > >>> 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. > > > > My plan is to get the first platform in, then I will maintain > Freescale stuff. So you can be sure I will continue to improve it. > One reason to get these code in early is to enable our partners and > early adopters to use u-boot. After all, this is the second ARMv8 > platform. The first one vexpress_aemv8a doesn't even support cache.
For the record, I'm OK with this plan given York's track record in the U-Boot community. -- Tom
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