Reserved RAM for unknown purpose

[Marco_Savo]

Hello, I am new here

Board:

conga-SMX8-Plus

imx8mp-cgtsx8p

I am working with the congatec BSP, our idea is to use it without any graphics audio or secure part; also the M7 is kind of useless for now.

I disabled everything related to audio - GPU - TEE - CMA etc.

Still, I have a big chunk of RAM reserved for something.

Where I can edit the reserved memory? some kernel header file in the yocto build system?

Dmesg

[    0.000000] OF: reserved mem: initialized node vdev0buffer@94300000, compatible id shared-dma-pool

[    0.000000] NUMA: No NUMA configuration found

[    0.000000] NUMA: Faking a node at [mem 0x0000000040000000-0x00000000bfffffff]

[    0.000000] NUMA: NODE_DATA [mem 0xbfc30b00-0xbfc32fff]

[    0.000000] Zone ranges:

[    0.000000]   DMA      [mem 0x0000000040000000-0x00000000bfffffff]

[    0.000000]   DMA32    empty

[    0.000000]   Normal   empty

[    0.000000] Movable zone start for each node

[    0.000000] Early memory node ranges

[    0.000000]   node   0: [mem 0x0000000040000000-0x00000000923fffff]

[    0.000000]   node   0: [mem 0x0000000092400000-0x00000000a43fffff]

[    0.000000]   node   0: [mem 0x00000000a4400000-0x00000000bfffffff]

[    0.000000] Initmem setup node 0 [mem 0x0000000040000000-0x00000000bfffffff]

Memory: 1736016K/2097152K available (15552K kernel code, 1408K rwdata, 5808K rodata, 2624K init, 527K bss, 361136K reserved, 0K cma-reserved)

[Marco_Savo]

I guess I should edit ./build-dir/workspace/sources/linux-congatec-sx8p/arch/arm64/boot/dts/freescale/imx8mp.dtsi

And I can safely delete these?

dsp@92400000

isp0@94400000

vdev0vring0@942f0000

dsp_reserved_heap

linux,cma

vdev0buffer@94300000

vdev0vring1@942f8000

[Marco_Savo]

Doesn't work, board broken. Not safe to delete these...

[Dhruvit]

Hi @Marco_Savo,

I hope you are doing well.

It is not recommended to delete those nodes.

However one can reduce or zero out the size.

linux,cma is required for many drivers so removing it may cause issues.

Thanks & Regards,
Dhruvit Vasavada

[Marco_Savo]

Hello, as already burned a chip on the board because your colleague said to try it, so now there is no problem as don't need hpmi, but still...
It is safe what are you suggesting?
can safely zeroes these?

dsp@92400000

isp0@94400000

vdev0vring0@942f0000

dsp_reserved_heap

vdev0buffer@94300000

vdev0vring1@942f8000

[Sanket_Parekh]

Hello @Marco_Savo,

I hope you are doing well.

"It is safe what are you suggesting? can safely zero these?"
->Yes, it is safe to do, If you don't have any requirements like camera integration, multimedia, audio, and rpmsg(auxiliary core(Cortex-M7) communication)

I hope this helps!

Thanks & Regards,
Sanket Parekh

[Sanket_Parekh]

Hello @Marco_Savo,

I hope you are doing well.

Yes, Please edit the file as required and suggested in the Documentation section, Please share the observation.
If it works or not.

Thanks & Regards,
Sanket Parekh

[Marco_Savo]

I don't need Cortex-M7, DSP, NPU, GPU. I have 25% of RAM reserved for these. How I disable them completely and free the RAM?

[Sanket_Parekh]

Hello @Marco_Savo,

I hope you are doing well.

How to disable Cortex-M7, DSP, NPU, and GPU?

->In the menu configuration enable the following module for the GPU driver: CONFIG_MXC_GPU_VIV is a configuration option for the GPU driver. In the menu config, this option is available under Device Drivers > MXC support drivers > MXC Vivante GPU support > MXC Vivante GPU support. On the screen displayed, select Configure the kernel, select Device Drivers > MXC support drivers > MXC Vivante GPU support > MXC Vivante GPU support, and then exit. When the next screen appears, select the following options to enable or disable the GPU driver:
• Package list > imx-gpu-viv
• This package provides proprietary binary libraries, and test code built from the GPU for framebuffer

One can view the power consumption app note:
https://www.nxp.com/docs/en/application-note/AN12778.pdf

->Regarding disabling NPU, Please refer to the below given changes.
https://lore.kernel.org/all/20220214125525.26954-1-peng.fan@oss.nxp.com/T/

Please refer to the below link as a reference and modify the status to disabled from okay in the respective device tree that one is using.
https://coral.googlesource.com/linux-imx/+/refs/heads/master/arch/arm64/boot/dts/freescale/fsl-imx8q...

->It is not possible to disable the CoreM7, for reference, I suggest referring to the below link.
https://community.nxp.com/t5/i-MX-Processors/IMX8MPlus-Disabling-M7-core/m-p/1376278#M183485

I hope this helps!

Thanks & Regards,
Sanket Parekh

[Marco_Savo]

CONFIG_MXC_GPU_VIV is not even present in the kernel config.

[Sanket_Parekh]

Hello @Marco_Savo,

I hope you are doing well.

Please refer to the below file at the given location in the Linux source code.
<Linux_src_code>/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt

I suggest referring to the below link for reference.
https://community.nxp.com/t5/i-MX-Processors/imx8x-reserved-memory/td-p/1614508

I hope this helps!

Thanks & Regards,
Sanket Parekh