[Qemu-arm] Running u-boot on raspi2

[Bonnans, Laurent]

Hi,

We (mostly Cheng Xiang's work) have been trying to use the raspi2 
machine to boot an image through u-boot.
It seems, however, that there are some missing pieces:

The first problem is that it trips very early if we keep the cpus count 
at 4 but will continue if we hard-patch it to be a single core.
Symptom is that it seems all cores are running and trying to execute 
something, while u-boot probably has not intention of doing something 
with SMP.
Our guess is that it's something related to the asm spin routine in 
raspi.c, which is maybe awoken too soon by some event in the mbox?

Second problem is that u-boot relies on some SoC timer for the 
raspberrypi 2, "System Timer" in 
https://www.raspberrypi.org/app/uploads/2012/02/BCM2835-ARM-Peripherals.pdf
It has not been added to qemu, to our knowledge but it looks like it 
should be pretty easy to emulate.

If we remove the timer accesses on u-boot + sets the cpu count to 1, the 
machine boots fine up to the kernel (minus the PLL related warning 
mentioned earlier in the list).

The first issue seems harder to resolve. Does anybody have a clearer 
picture on what could be the problem?

Cheers,

Laurent