On Sat, Jul 4, 2020 at 3:53 PM Simon Glass sjg@chromium.org wrote:
Hi Peter,
On Fri, 3 Jul 2020 at 06:33, Peter Geis pgwipeout@gmail.com 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'm building the cardhu board with tweaks for Ouya's specifications similar to my work for the linux kernel. I build the image using mkbootimg --kernel u-boot.bin --ramdisk /dev/null --output u-boot-android.bin. I then fastboot boot u-boot-android.bin.
I've tried tweaking the text base and tried both standard debug and low level debug.
Do you think you could give me some insight into where I'm going wrong?
Is it possible that fastboot expects a relocatable image? If you set up the debug UART very early you might be able to output a character in start.S ?
Yes, fastboot expects a relocatable image. As I understand it though, if I get the text base correct, U-boot will not need to relocate.
The debug UART is already set up when it fastboot jumps to the loaded kernel, So I should be able to dump data to the expected raw address and it will show up?
BTW does U-Boot have support for the fastboot protocol? Perhaps you could just use U-Boot?
The Ouya is locked with a signed boot loader, like most consumer android devices. Unlike most other devices, it does not have a hardware method for entering the bootloader in case of a brick. We are currently using a hacked kernel that stores another kernel in "safe" ram via kexec and hard resets the board, but a proper bootloader would be much more preferable.
I found one example of where fastboot chainloaded u-boot successfully on the galaxy nexus, from 2013. https://forum.xda-developers.com/galaxy-nexus/bootloader-boot-multi-boot-sup...
Regards, Simon