On 07/02/2014 02:12 PM, Stephen Warren wrote:
From: Stephen Warren swarren@nvidia.com
In at least Tegra124, the Tegra memory controller (MC) has a register that controls the memory size. Read this to determine the memory size rather than requiring this to be redundantly encoded into the ODMDATA. This way, changes to the BCT (i.e. MC configuration) automatically updated SW's view of the memory size, without requiring manual changes to the ODMDATA.
Future work potentially required:
- Clip the memory size to architectural limits; U-Boot probably doesn't and won't support either LPAE or Tegra's "swiss cheese" memory layout, at least one of which would be required for >2GB RAM.
- Subtract out any carveout required by firmware on future SoCs.
I noticed that this patch triggers a bug in DT relocation during bootm/bootz. It'd be best if the following were applied somewhere before this patch:
http://patchwork.ozlabs.org/patch/375408/ lib: lmb: fix overflow in __lmb_alloc_base w/ large RAM
That's because this patch changes the RAM size on Tegra124 from 2GB-1MB to 2GB. I believe that change is correct, it just triggers an overflow in U-Boot's RAM handling which needs to be fixed first.
In practice, I suspect even if this dependency is ignored, there will be no user-visible impact, because the default environment in Tegra U-Boot disables DT relocation completely. This problem would only affect someone who flashed/ran a U-Boot with this patch without resetting their environment to the default that's embedded into the new U-Boot, and their environment in flash was older than when we disabled DT relocation. Since tegra-uboot-flasher always does reset the environment, I expect most people would never notice this.