On 02/25/2015 02:30 AM, Vincent wrote:
Hi,
as explained here http://community.arm.com/message/25127, it is possible to
boot the raspberry 2 in secure mode, by adding the kernel_old=1 option in
config.txt. The main effects of this option are:
- all 4 cores start executing in secure SVC mode instead of non-secure SVC
mode
- all 4 cores start at 0x0000 instead of 0x8000
- the initial boot code that setup SMP and exits secure mode is not
executed
After browsing u-boot's source code, it seems that their boot code is more
or less extracted from what u-boot is doing. However I didn't manage to
compile u-boot for the raspberry 2 supporting this secure mode.
Could anyone explain me what options I need to configure in rpi_2_defconfig
so that u-boot supports secure boot for the raspberry 2 and what the boot
sequence will be in this case ? I don't mind fixing the code if necessary
but I'm a bit lost in the order of events in the initialization.
(Luckily I just happened to notice this message while looking at another
one nearby. CCing the relevant board maintainer(s) explicitly would help
your messages be noticed)
To modify U-Boot to support the alternate entry point/load address,
you'd hopefully only need to change the definition of
CONFIG_SYS_TEXT_BASE in include/configs/rpi*.h.
I wasn't aware of the thread/option you mention, so I have not attempted
to boot the RPi2 U-Boot in secure mode. If you're lucky, U-Boot itself
will "just work" once TEXT_BASE is fixed.
To boot a kernel, you'll probably need to at least configure the ARM
architected timers CNTFRQ register for the kernel. Perhaps there are a
few other things like that missing?
It might be interesting to enable U-Boot's PSCI support on the RPi2, so
that an upstream kernel could gain SMP support without the need for
explicit BCM2836 SMP support code.
So far, I haven't attempted anything with an (upstream) kernel on RPi2,
just U-Boot.
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