Multi-Soc binary support for i.MX8M Mini/Nano/Plus/? in single boot firmware binary

[Peng Fan (OSS)]

On 2021/5/27 23:41, Tim Harvey wrote:
> Greetings,
> 
> I support various iMX8M PCB's via board/gateworks/venice that are SOM 
> based and we are starting to add SOM's that have different IMX8M variant 
> SoC's on them which for various reasons are not binary compatible. I'm 
> very interested in coming up with a way to make them binary compatible 
> to reduce the number of disk images and boot firmware binaries our users 
> work with (along with the confusion of which one they need to use).
> 
>  From what I see in working thus far with the IMX8M Mini, Nano, and Plus 
> boot firmware differs in the following ways:
> - different primary image offsets
> - different dram config (phy training blob, phy cfg, cfg; which total 
> about 3KiB for each config which varies based on dram type, soc variant, 
> dram topology and bit-mapping)
> - different OCRAM sizes (compat binary would have to use the minimum 
> size ie 256K)
> - different ATF binaries
> - different ATF load address
> - different pinmux/padconf/inputsel registers
> - different clk config
> 
> The primary image offsets should be able to be dealt with by placing 
> jumps at the various offsets and I believe the rest could be dealt with 
> via runtime code if the SPL could load soc-specific blobs including dram 
> config, ATF, binary firmware blobs from a nice indexed image such as FIT 
> or binman. Currently imx8m SPL's use FIT images that are loaded entirely 
> into OCRAM which becomes an issue when you have enough dram configs that 
> they no longer fit in the OCRAM.
> 
> Does anyone agree this is doable or is there something they see that 
> would be a show-stopper?
> 
> I'm not all that familiar with the merits of binman fs FIT images... I 
> think they were developed for different things. I'm not sure if 
> either/both are suited for what I'm talking about regarding having the 
> SPL raw load binary blobs vs having them tacked onto a FIT image.
> 
> I'm not sure if the imx8mq has enough in common to be able to do this 
> with either, in fact I'm not even clear with SoC that is (is it what NXP 
> calls i.MX 8M?)

i.MX8MQ not have enough OCRAM for this case. SPL already use TCM here.

Regards,
Peng.

> 
> Best regards,
> 
> Tim