# Application cores and microcontroller cores on one chip

Many processors that run Linux also include a small microcontroller core, which handles time-critical work while Linux does the rest.

Page: https://dharanova.com/learn/heterogeneous-socs · Track: Think · Level: Core · Facts last checked 6 October 2026

Read first: [Anatomy of an application-processor system](https://dharanova.com/learn/anatomy-of-an-mpu-system.md)

Diagram: One chip holds a Cortex-A block running Linux and a Cortex-M companion core running its own firmware. An arrow labelled remoteproc goes from the Cortex-A side to the Cortex-M core: load firmware, start, stop. A two-way arrow labelled RPMsg carries messages both ways. Below: some chips also mix fast and efficient application cores (Arm big.LITTLE or DynamIQ), and under light load the OS can move work to the efficient cores. A last line lists example chips from ST, NXP, TI and Renesas with their Cortex-A and Cortex-M cores.

## Key points

1. Pairing Cortex-A and Cortex-M cores is common across vendors: for example ST STM32MP15 (Cortex-A7 + Cortex-M4), NXP i.MX 8M Mini (Cortex-A53 + Cortex-M4), TI AM62x (Cortex-A53 + Cortex-M4F) and Renesas RZ/G2L (Cortex-A55 + Cortex-M33). [1][2][3][4]
2. Linux manages the companion core through the remoteproc framework (load firmware, start, stop) and exchanges messages with it over RPMsg. [5][6]
3. Some application processors also mix fast and efficient cores of their own (Arm big.LITTLE or DynamIQ), so the operating system can move work to the efficient cores when the load is light. [7][8]

## Where to go next

- [On-device speech-to-text for VAHA: the model, where transcription happens, and a first accuracy test](https://dharanova.com/whitepapers/vaha-on-device-speech-to-text.md): a whitepaper from our lab

## Sources

1. [STM32MP157F](https://estore.st.com/en/stm32mp157faa1-cpn.html), STMicroelectronics
2. [i.MX 8M Mini](https://www.nxp.com/products/i.MX8MMINI), NXP
3. [AM625](https://www.ti.com/product/AM625), Texas Instruments
4. [RZ/G2L](https://www.renesas.com/en/products/rz-g2l), Renesas
5. [Remote Processor Framework](https://docs.kernel.org/staging/remoteproc.html), kernel.org
6. [Remote Processor Messaging (rpmsg) Framework](https://docs.kernel.org/staging/rpmsg.html), kernel.org
7. [Arm DynamIQ](https://www.arm.com/technologies/dynamiq), Arm
8. [big.LITTLE technology](https://www.arm.com/technologies/big-little), Arm