[U-Boot] u-boot on raspberry 2: booting in SVC secure mode

[Stephen Warren]

On 02/26/2015 02:32 AM, Vincent wrote:
> I tried what Stephen suggested, and just changing CONFIG_SYS_TEXT_BASE
> to 0x0 (with kernel_old=1) does not work: the board display some garbage
> on the uart then hangs. The content of the garbage makes me thinks that
> nothing is done to handle the four cores in this setting which ends up
> badly. I expected this since raspberry's "firmware" only let one core
> run free. I think I need to configure U-boot so that it deals with this
> SMP scenario (I just don't know how).

That expectation seems correct! I hacked in some code right at the start
of U-Boot (reset: in arch/arm/cpu/armv7/start.S) that extracted the
CPUID from the MPIDR register, and only allowed CPU0 to continue. With
that in place, kernel_old=1 and CONFIG_SYS_TEXT_BASE=0 worked.

Interesting that all CPU cores get released at reset; the other SoCs
I've used only release CPU0 and you have to explicitly boot CPUn.

> My goal is to use U-boot to load some small homemade baremetal kernels
> on the raspberry (using serial or tftp loading), in *secure mode*, so I
> need U-boot to stay in secure mode, or at least let me install my own
> secure_monitor code before switching to non-secure mode.
> 
> I made a couple attempts of adding secure mode support by adding options
> in configs/rpi_2_defconfig but they don't seem to be taken into account.
> Where do you suggest I put ARMV7_virt and ARMV7_NONSEC ?

I would suggest adding #defines to include/configs/rpi_2.h.