topic Re: Can Cortex-M4 core use OCRAM without conflicting by linux or u-boot? in i.MX Processors

Can Cortex-M4 core use OCRAM without conflicting by linux or u-boot?

Takashi_Kashiwagi — Wed, 21 Aug 2019 01:45:34 GMT

Hi Community.

I'm making a program for the CM4 core. I would like to use OCRAM because TCM seems to lack capacity.

I think that linux doesn't seem to use OCRAM, but I didn't know if u-boot was using it.

Does anyone know how OCRAM is used by u-boot and linux?

(It is good for me that OCRAM is only used by BootROM.)

Best Regrads,

T.Kashiwagi

Re: Can Cortex-M4 core use OCRAM without conflicting by linux or u-boot?

CarlosCasillas — Fri, 23 Aug 2019 01:02:54 GMT

Hi Kashiwagi,

You could refer to U-Boot source code to determinate on which memory is running. On i.MX8M series, it was also included the use of the SPL, so, it may be required to also consider this. The following thread seems to be related:

Building SPL/u-boot to boot from SD on i.MX 8M QUAD EVK

Also, SPL is described on the link below, you could use it as reference:

http://trac.gateworks.com/wiki/ventana/bootloader

Additionally, in case of lacking capacity of the TCM, the M4 core could also run from DRAM; please refer to chapter 6 of “Getting Started with MCUXpresso SDK i.MX 8M Devices” document.

Hope this will be useful for you.
Best regards!
/Carlos
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Re: Can Cortex-M4 core use OCRAM without conflicting by linux or u-boot?

Takashi_Kashiwagi — Fri, 23 Aug 2019 06:26:32 GMT

Hi Carlos-san

Thank you for responding.

Thank you for the material. I will try it.

The background, we will use CM4 core for monitoring Linux (CA53 Core).

So, I don't want to use the DRAM area as much as possible.

Because I think that DRAM is initialized by DCD and u-boot.

Best Regards,

T.Kashiwagi