i.MX ProcessorsのトピックiMX7D internal ram memory map

iMX7D internal ram memory map

dry — Mon, 13 Aug 2018 03:20:54 GMT

This is a user problem reading + understanding manual:

The figure says 224 is free ( = 128(EPDC) + 64(128 - 64res) + 32(PXP) ), and "see note".

In note: "The entire OCRAM region can be used freely post boot. ... "

So can the entire OCRAM 288KB be used freely post boot, or only 224? (I can't say why I can't understand the doc ... ).

And if the 64KB is still reserved, what is it reserved for .. (is it secret :smileyhappy:) ?

Re: iMX7D internal ram memory map

Yuri — Mon, 13 Aug 2018 04:55:06 GMT

Hello,

The entire OCRAM 288KB be used freely post boot.

Have a great day,

Yuri

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Re: iMX7D internal ram memory map

dry — Mon, 13 Aug 2018 08:07:05 GMT

Thanks Yuri !

Re: iMX7D internal ram memory map

ivan_nikolaenko — Sat, 31 Jul 2021 14:29:47 GMT

Hello Yuri!

Do I understand correctly, that I can't use adresses 0x00900000-0x0090ffff for storing my Cortex-M4 firmware because this range is reserved by Linux kernel and is used by it during boot process?

As I see from FreeRTOS linker scripts - they all use 0x00910000 as a start address. I tried to edit default linker script to use first 0x00900000 and then 0x00901000 adresses as a start address along with disabling corresponding ocram entries in the devicetree, but I see that my M4 firmware stops working right after kernel starts booting.

I use imx-5.4.47 kernel
My modifications:
imx7d.dtsi:

ocram: sram@901000 { compatible = "mmio-sram"; reg = <0x901000 0x1f000>; clocks = <&clks IMX7D_OCRAM_CLK>; + status = "disabled"; };

my devicetree:

reserved-memory { #address-cells = <1>; #size-cells = <1>; ranges; m4_reserved: m4@0x00901000 { no-map; reg = <0x00901000 0x1f000>; }; };

Did I miss something?
Thanks in advance.