Re: AW: load BL31 on imx8mm and imx8mq

["Yazdani, Reyhaneh" <RYazdani@data-modul.com>]

On 6/26/19 12:25 PM, Rouven Czerwinski wrote:
>> And what is the reason behind decreasing 16 from returning address:
>>
>> MX8MQ_ATF_BL33_BASE_ADDR - 16
>>
>> I removed "16" for im8mq in Barebox and still works.
>
> This puts some distance between the stack and your execution address.
> As long as nobody is writing to the stack pointer before increasing it
> you are save and your return address is not overwritte. Your probably
> save anyway since the instructions at the address
> MX8MQ_ATF_BL33_BASE_ADDR are only executed once and don't manipulate
> the stack.
>
> The stack pointer inherently has nothing to do with the return address,
> you just have to make sure that the stack pointer is pointing to a
> valid address, othwise you may get aborts on stack usage.

Thanks for the explanation
>
>> The PLAT_NS_IMAGE_OFFSET is identical for imx8mq and imx8mm. Do you
>> have any idea why the firmware is not returned to this address?
>> Do we need to enable any special timer or clock for this point?
>> I used the same firmware as I have used in UBoot, thus the firmware
>> itself should be correct.
>
> It may be a good idea to build the TF-A yourself and enable the debug
> output therein to make sure that TF-A is not missing a crucial setup
> step. The TF-A can be found a
> https://source.codeaurora.org/external/imx/imx-atf/
> pick one of the release branches, enable the debug console in
> plat/imx/imx8mm/include/platform_def.h and build a Debug build with
> make plat=imx8mm DEBUG=1.

This helped me a lot. I found the reason. Actually the firmware did not execute
to the end. I had to configure GIC to sys_pll2_100m in the first steps of low-level.

Best regards,
Reyhaneh
>
> Regards,
> Rouven
>

--
Reyhaneh Yazdani
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