Centos 7 Increase CMA Size

[alperen]

I have a SBC module and it has Centos 7 with 3.10.0-1160.114.2.el7.x86_64 kernel version. I have to increase CMA size to 128MB which is default 4MB. I check my kernel menuconfig and DMA Contiguous Memory Allocation was enabled. I tried to way below:

1. Define CMA parameters: You can define CMA parameters in the /boot/grub2/grub.cfg file or other configuration files used by Grub2. These parameters are typically added to the kernel command line. An example CMA parameter looks like this:

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cma=256M

This sets the CMA size to 256 megabytes.

2. Update Grub configuration: You can add the defined CMA parameter to the Grub configuration file using the following commands:

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sudo vi /etc/default/grub

Add the CMA parameter to the GRUB_CMDLINE_LINUX line. For example:

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GRUB_CMDLINE_LINUX="... cma=256M ..."

3. Update Grub configuration: Save and exit the configuration, then update the Grub configuration using the following command:

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sudo grub2-mkconfig -o /boot/grub2/grub.cfg

4. Reboot the system: Reboot the system for the changes to take effect:

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sudo reboot

After did these I check my CmaTotal with

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cat /proc/meminfo

but it says CmaTotal 0kB and CmaFree 0kB.

How can I increase the CMA size in Centos 7?

Best regards.

[TrevorH]

Check in /proc/cmdline to see if your changes took effect.

[alperen]

Hi,

Thank you for your reply. You can find outputs in the link below:

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https://codefile.io/f/3oLhhDzXB8

I did exactly these but it didn't effect my CmaTotal.

Best regards.