On Sun, Jul 5, 2020 at 11:35 AM Simon Glass <sjg@xxxxxxxxxxxx> wrote: > > Hi Peter, > > On Sun, 5 Jul 2020 at 05:33, Peter Geis <pgwipeout@xxxxxxxxx> wrote: > > > > On Sat, Jul 4, 2020 at 3:53 PM Simon Glass <sjg@xxxxxxxxxxxx> wrote: > > > > > > Hi Peter, > > > > > > On Fri, 3 Jul 2020 at 06:33, Peter Geis <pgwipeout@xxxxxxxxx> 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? > > Yes, so long as you know the address. Is the MMU turned off? Cache? It is unknown what state either of these are in, since I am unfamiliar at all with how fastboot functions with these. In U-boot yes the MMU was enabled as well as both I and D cache. > > > > > > > > > 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. > > OK. Maybe there is someone on this list with a bit more Android > booting experienec? > > > > > 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-support-t2201146 > > OK, I'm sure it is possible. Do you have the source code for the > fastboot code that boots U-Boot? No, we have the reference code here: https://android.googlesource.com/platform/bootable/bootloader/legacy/+/b1fde5cd7d5158b8e6876139ca76a341d0e49708/usbloader/usbloader.c Unfortunately the behavior observed in the Ouya shows it has been heavily modified from this baseline. I've reached out to the dev who performed the work on u-boot for insight as well. > > Regards, > Simon
