From mboxrd@z Thu Jan 1 00:00:00 1970 From: York Sun Date: Fri, 6 Jun 2014 07:52:44 -0700 Subject: [U-Boot] [Patch v4 2/5] ARMv8: Adjust MMU setup In-Reply-To: References: <1401396548-3353-1-git-send-email-yorksun@freescale.com> <1401396548-3353-2-git-send-email-yorksun@freescale.com> <20140602113450.GD13573@leverpostej> <538CA0F5.2060103@freescale.com> <20140602180100.GA887@leverpostej> <538F48F2.3080408@freescale.com> <20140605100926.GA6430@leverpostej> <539087A5.4090803@freescale.com> <20140605174156.GG31564@leverpostej> <5390B82F.5040601@freescale.com> Message-ID: <5391D5BC.8030004@freescale.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On 06/06/2014 06:34 AM, Rob Herring wrote: > On Thu, Jun 5, 2014 at 1:34 PM, York Sun 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. York