imx.8 core operation under OS

[ilyakrasavin]

Hi all.

The question is about imx8 chip. It reportedly has both Cortex A53 and A72 cores. How is it supported by linux? Can linux run on both types of cores simultaneously or just one type of core is used and the other remains in reset?

Thanks.

Ilya

[david_dicarlo]

Apologies for the late update to this thread.

The above mentioned DTB files will limit operation of the i.MX8QM (two A72 cores) or i.MX8QP (one A72 core) to just one kind of core or the other (A72(s) or A53s only), but the device hardware is not limited to just that.

The standard linux BSP image ships with a number DTB files for various configurations, where the most common bring up both kinds of cores. The default DTB brings up all 6 cores (or 5 in the case of the QP). The latest kernel also permits hotplugging the cores, so the user can use just one core or all 5/6 of them, depending on the application needs.

[bspranger]

I am looking into utilizing the i.MX 8QuadMax (IMX8QMAEC).

Can you confirm that linux can utilize both the two A72 Cores @1.6Hgz and the four A53 cores @ 1.2 Ghz?

[Rita_Wang]

No, the A53 and A72 core can not work simultaneously. Yes, as you said only one type of core is used. In the linux BSP you can choose different core by the dts file

• Image-fsl-imx8qm-mek_ca53.dtb: Supports four CortexA53 cores only.
• Image-fsl-imx8qm-mek_ca72.dtb: Supports two Cortex-A72 cores only. You need to build the special boot image through the imxmkimage tools, and select the flash_ca72 build target.

[ilyakrasavin]

Thanks, Rita. So, these core complexes cannot operate simultaneously. Is there any possibility to manage these cores in run time. For example to start running on A72 and then to switch (to turn off A72 and to turn on A53) between them?

Thanks,

[Rita_Wang]

Sorry, no, you can not do that when you run single system on this board. The A72 and A53 can not work at the same time.