limit memory space on i.MX8mQ

[kayiyeh]

I have an i.MX8mQ EVK which have a LPDDR4 of 3GB. I want to verify if my application can run under 2GB or even 1GB memory and don't want to change the board components at this moment. Is that possible to change some setup and let the kernel just see 2GB memory space?

[igorpadykov]

in uboot change parameter #define PHYS_SDRAM_SIZE

in uboot/include/configs/imx8mq_evk.h

Best regards
igor

[kayiyeh]

Dear Igor,

Sorry I am new to the embedded Linux. I can’t find the file to make the change. Can you tell me where the repository is to get the source code?

Thanks a lot.

Regards,

Ka-Yi

[igorpadykov]

Hi Ka-Yi

please check uboot-imx - i.MX U-Boot 

imx8mq_evk.h\configs\include - uboot-imx - i.MX U-Boot 

Best regards
igor

[kayiyeh]

Dear Igor,

I do find the file you memtioned and edit the file. However, I go back to bitbake the image and the bitbake tells me nothing to do and no new image generated. would you please tell me how to bake a customized image?

BR

KY

[igorpadykov]

Hi KY

one can look at

https://community.nxp.com/docs/DOC-100203 

i.MX Yocto Project: How can I (quickly) modify the kernel and test it? 

Best regards
igor

[gary_bisson]

Hi,

You can add 'mem=2G' or 'mem=1G' to your kernel boot arguments (passed by U-Boot) as explained in the kernel documentation:

linux/kernel-parameters.txt at master · torvalds/linux · GitHub 

Regards,

Gary

[kayiyeh]

Dear Gary,

Thank you. However, I tried to set the command in uboot then type “saveenv”, and use “printenv” to make sure, then type “boot” to boot.

Unfortunately, after finish booting, I found the system still has 3G memory. Can you tell me what’s wrong?

I read the document you refer and it said there is another command “memmap” may need to set. I don’t know how to set that though. Would you please teach me?

Regards,

Ka-Yi