[PATCH v2] Raspberrypi: updated the console interface.

[Christian Mauderer]

On 29/12/2019 15:23, Niteesh wrote:
> Where does qemu place the dtb file? we can pass the dtb file to the kernel
> using -dtb, but not sure where it puts it? googled a lot but couldn't
> find it.

I'm not really sure where qemu places a dtb. Maybe it helps if I
describe roughly how it would work normally on other ARM BSPs?

- Some bootloader (often U-Boot, for the raspberry the odd raspberry
bootloader) loads the dtb to some specific memory location.

- The location is stored in some register (I think R6) before the
bootloader hands over to Linux or RTEMS

- RTEMS copies from there during an early initialization stage (search
for bsp_fdt_copy in start.S)

I just noted: It's possible that the beagle BSP doesn't use the FDT yet.
It doesn't define the BSP_START_COPY_FDT_FROM_U_BOOT. You should add that.

> 
> I also tried running u-boot, it successfully ran on raspi3 in 64bit
> mode. I couldn't get it running on raspi2.
> The qemu raspi3 doesn't support networking nor usb, but qemu raspi2
> does, so if we could get u-boot
> working on raspi2 it would make your work way better.
> Could you give it a try?

What would we gain by running U-Boot?