On 2/11/19 3:48 AM, Thierry Reding wrote:
On Mon, Feb 11, 2019 at 10:04:37AM +0000, Tristan Bastian wrote:
Thierry Reding – Mon, 11. February 2019 10:38
On Mon, Feb 11, 2019 at 09:20:33AM +0000, Tristan Bastian wrote:
Thierry Reding – Mon, 11. February 2019 9:52
On Sun, Feb 10, 2019 at 08:53:11PM +0100, Tristan Bastian wrote:
Thierry, do you have any news on this?
I don't think, that google is going to push an updated version of
coreboot
to each nyan-big device.. So reverting this patch at least for the nyan devices would be the best
I
think..
Yes, I agree. I had a brief chat with Rob Herring about this and he too agrees that we should revert it for now. I'll make it a manual revert and add a comment to the device tree node that will hopefully avoid any future janitorial "cleanups" of this sort.
great news! :)
BTW: I'm now running u-boot natively and it seems like u-boot always has
a
problem with the memory.. If u-boot is used chainloaded to coreboot it is only getting 2GB of
memory
and running u-boot natively also just gives me 2GB.. I've tested that with a kernel with "ARM: tegra: Fix unit_address_vs_reg
DTC
warnings for /memory" reverted and also on a kernel, before this patch
was
applied..
It's possible that U-Boot doesn't support LPAE and therefore may not be able to use more than the 2 GiB of memory.
So I at least enabled LPAE in u-boot with "CONFIG_ARMV7_LPAE=y" and this was for some reason also needed to get some output on the display.. I'm not sure why LPAE needs to activated in u-boot for display output on the nyan-big.. Without LPAE enabled u-boot was still working, and booted linux, but u-boot didn't display anything on screen, linux then did..
Yeah, that's surprising. Perhaps without LPAE U-Boot thinks there's not enough memory for the framebuffer? There should be plenty, so maybe there is something else going on here.
However, U-Boot should be able to tell the kernel exactly how much memory the system has and pass that on via device tree. That still does work, right?
It seems like this is not working.. And this seems to be the case with both, u-boot chainloaded and running u-boot natively..
I've used these scripts for flashing: github.com/NVIDIA/tegra-uboot-flasher-scripts And used the norrin device since it seems like it is the nyan-big dev board? But going with the norrin device config should not be the issue here since the problem also exists when chainloading u-boot, right?
It could be a problem. The memory bank configuration is stored in what's called a BCT along with a bunch of other parameters that define what the memory controller needs to access the given memory chips. So if you've flashed a BCT that's for a board with only 2 GiB of memory you would end up with a system that can't address any more than that. It's somewhat surprising that memory accesses work at all with a BCT that's for different memory chips, but sometimes you can get lucky.
You may want to try reflashing with the right BCT. The simplest would probably be to duplicate the cbootimage configuration for Norrin and substitute the relevant bits by what you have from the Chromebook flash utilities. Looks like the BCT in really the only thing you can replace there. Make sure to replace it with the one that matches your Chromebook and it should give you the right memory bank configuration.
Is there a way to check if the correct bct for my 4GB model was used? What I tried was to edit the existing bct config file of norrin from here: https://github.com/NVIDIA/cbootimage-configs/blob/master/tegra124/nvidia/nor... by replacing all entries for each memory bank with the entries from here: https://github.com/coreboot/coreboot/blob/master/src/mainboard/google/nyan_b...
I also added the SDRAM[0], SDRAM[1], SDRAM[2], SDRAM[3] each time in front of each line.. This also booted for me, but also just leaves me with only 2Gb of my 4GB..
And since this problem also occurs, when chainloading u-boot, this must be a problem with u-boot, I think..
Not necessarily. U-Boot reads the memory size from EMC registers and those EMC registers are programmed based on the contents of the BCT. So if the BCT is wrong, then it's going to be wrong irrespective of what bootloader you use.
That said, I does indeed look as if U-Boot only supports 2 GiB of memory on 32-bit Tegra. arch/arm/mach-tegra/board.c contains the relevant code. If you look at dram_init() it uses query_sdram_size() to get the size of RAM. That will allow to convey up to 4 GiB of RAM, but then the code in board2.c (see dram_init_banksize()) only uses a single bank on 32-bit Tegra (CONFIG_PHYS_64BIT is only set for 64-bit Tegra).
According to the comments for dram_init_bank_size() we can't store the second bank because the .start field is 32 bits wide and therefore can't store the 0x100000000 start address for the bank.
It sounds to me like ARMV7_LPAE should perhaps select PHYS_64BIT to make sure all the appropriate variables can store addresses beyond the 32-bit boundary. It's one thing to not support > 2 GiB of memory in U-Boot, but it's an entirely different story if we can't even pass > GiB of memory to the kernel if they exist.
Stephen, do you remember if there was anything preventing us from going 64-bit for phys_addr_t and phys_size_t on LPAE enabled systems?
We probably just never tried since we never needed it and/or LPAE wasn't available (in U-Boot SW) when it initially might have been useful. I would not be surprised if some of the low-level Tegra code in U-Boot conflates 64-bit support with SoC being >= T210, so things might not be as simple as enabling CONFIG_PHYS_64BIT, but you never know...