[meta-xilinx] SPL->ATF->Linux

[Michal Simek]

On 11. 06. 19 22:08, Jean-Francois Dagenais wrote:
> Anyone?
> 
>> On Jun 10, 2019, at 23:51, Jean-Francois Dagenais <jeff.dagenais at gmail.com> wrote:
>>
>> Hi guys,
>>
>> Is this possible? I am shooting for fastest boot possible and thought this would be the way to achieve it. What is the smallest cost I have to expect for having u-boot proper in the boot flow? I.e. is my assumption that I must skip it to achieve fastest boot true.
>>
>> FYI, I've decided to postpone fpga load to linux init. This simplifies things a bit in SPL, but there is still the mix of ATF and Falcon which I am not sure. I am fuzzy on the ATF terminology so thank you for bearing with me as I learn.
>>
>> Can anyone point to a working example (board config .h and defconfig files for example) or which pieces are required to make it work. 
>>
>> I found this on arm-community: "Solved the problem. U-Boot SPL copies ATF in OCRAM, and ATF calls Kernel directly passing in the FDT address."
>>
>> BTW, we boot both SD and eMMC on the same board. Right now I got my SPL to open a FIT image made by kernel-fitimage.bbclass but it obviously doesn't go far.
>>
>> But its still a bit vague. If I have to guess, the FIT image would describe to load the kernel at an address which also appears in my dts/dtb so ATF knows where to jump to next.
>>
>> Thanks for clues an pointers fellas!
> 
> 
> Please help. Michal, I saw you were involved with this...
> https://lists.denx.de/pipermail/u-boot/2016-October/269080.html
> 
> I am drowning in a sea of legacy and generic code flows within SPL. I am wondering what design/methods to use if doing a new zynqmp based design. I see a bunch of flows where different images can be loaded:
> 
> CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
> CONFIG_SPL_FS_LOAD_ARGS_NAME
> CONFIG_SPL_FS_LOAD_KERNEL_NAME
> 
> I see comments in include/configs/xilinx_zynqmp.h like "/* u-boot is like dtb */" which adds to the confusion.
> 
> ... or should I try, if at all possible, to boot directly to linux from FSBL? Or do this https://xilinx-wiki.atlassian.net/wiki/spaces/A/pages/18841976/Prepare+boot+image#Preparebootimage-Example:FSBLpre-loadsLinuximages and make a very stripped down u-boot proper (no MMC driver needed), and boot into pre-loaded kernel?

There is no real need to run any u-boot if you want to short boot up
time. Just let fsbl to load ATF and ATF directly starts kernel.

Thanks,
Michal