On Fri, Aug 21, 2020 at 05:30:54PM -0400, Peter Geis wrote:
On Fri, Aug 21, 2020 at 5:04 PM Tom Rini trini@konsulko.com wrote:
On Fri, Aug 21, 2020 at 04:17:24PM -0400, Peter Geis wrote:
On Mon, Jul 6, 2020 at 3:48 PM Peter Geis pgwipeout@gmail.com wrote:
On Mon, Jul 6, 2020 at 1:04 PM Stephen Warren swarren@wwwdotorg.org wrote:
On 7/3/20 6:32 AM, Peter Geis wrote:
Good Morning,
I am attempting to expand on the work for chainloading U-Boot on the nyan-big in order to chainload U-Boot on the Ouya Tegra30 device from fastboot. I have so far been unsuccessful at getting any output from U-Boot through this method.
I assume that fastboot executes the loaded code on the main CPU not on the boot CPU (AVP). U-Boot SPL on Tegra30 expects to start running on the AVP though; you would have to disable SPL to make this all work, and perhaps fix U-Boot to work without SPL present. I'm not sure what, if any, changes would be required to support that.
For background, see: https://http.download.nvidia.com/tegra-public-appnotes/index.html
Apologies for the resend, I realized I didn't reply to the list.
I admit I'm still extremely new to U-Boot, but this is the way I understand the boot flow. ROM does extremely low level init, then loads U-boot SPL. U-Boot SPL does basic init, ram, cpu and required peripherals, then loads U-Boot.bin. U-Boot.bin is U-Boot proper, with the full interface.
By loading U-Boot.bin as the nyan instructions indicated, I'm bypassing the SPL code as if it was already complete. The issue I have is I'm not sure what modifications were done to the T124 code to allow nyan to do this. I've compared the nyan configs to the cardhu configs and I don't see anything that sticks out to me. I've also dug through the nyan git log and I don't see anything that was specifically changed to allow chainloading on T124.
I also am unsure of where fastboot is loading the kernel in order to set the text base correctly.
For anyone interested, I succeeded at chainloading u-boot on the Ouya.
Nice work.
The Linux Kernel with low level debugging enabled in the decompressor will print the load address.
Jumping to kernel at:4861 ms
C:0x80A000C0-0x8112BA40->0x8152C700-0x81C58080 Uncompressing Linux...
So by setting the u-boot text base to 0x80A00000 u-boot now executes, but it would then immediately silently reboot. Turns out I needed to define the console in the device-tree, which isn't defined in the u-boot tegra30-cardhu.dts. It would then freeze at relocation time, as it was trying to overwrite the trustzone ram space. #define CONFIG_PRAM 2048 solves that issue.
I'd like to know if u-boot can read the reserved-memory device-tree node and use it instead of CONFIG_PRAM?
Honestly, this is what CONFIG_PRAM is for. We could possibly add something to get this from device-tree, but we might need to do that early enough that it becomes a tricky thing to do.
Thank you, that makes sense.
Otherwise the only issue it seems to have it is does not read the nvidia proprietary partition table. Is there a way to force u-boot to read the backup gpt table similar to the android kernel's method?
Some tangential experiments the other day and I saw that U-Boot would read the backup GPT if it's at the expected place. But that might be only after you do something like "part list mmc 0", so there might in turn be places that we need to be a bit more robust in our checking.
Unfortunately running <part list mmc 0> returns "## Unknown partition table type 0"
This is the result of the gpt guid command: Tegra30 (Ouya) # gpt guid mmc 0 GUID Partition Table Header signature is wrong: 0x1000 != 0x5452415020494645 find_valid_gpt: *** ERROR: Invalid GPT *** find_valid_gpt: *** Using Backup GPT *** 00000000-0000-0000-0000-000000000000 success!
The backup GPT is a valid GPT, and linux will pull the partition table from it if forced to look there. The android kernel handled this by adding "gpt gpt_sector=15073279" to the command line.
Ah, interesting. And where is that sector in relation to where the backup should be? I'm not sure off-hand how easy it would be to make backup location easy to run-time configure, but if it's lba - 2 instead of lba - 1 or something, we could add a build-time "also check.." thing, if it's a consistent offset, and probably is. Similarly, we could add something kinda ugly to allow overriding GPT_PRIMARY_PARTITION_TABLE_LBA with where that is instead.
Other-otherwise, I know there's patches in progress to support "tegra partition table" for Linux and doing that for U-Boot could be handy and fix this problem as well?