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👉 Previous article:“Realtek Launches the Ameba Linux Solution: Building an Open, Production-Ready Embedded Linux Platform” provides a detailed introduction to the complete DDR-based Linux solution.
❓Does a Linux solution necessarily require expensive, high-capacity DDR?
❓For low-cost IoT products, can more cost-effective PSRAM be used to support Linux?
This article provides a direct answer: 8MB of PSRAM is enough to support a Linux runtime environment and basic Wi-Fi connectivity.

Embedded Linux is commonly associated with a fundamental assumption in the industry: running Linux requires high-capacity DDR. This hardware barrier leaves many lightweight IoT terminals facing a difficult choice:

❌ To benefit from the Linux software ecosystem and reliable Wi-Fi connectivity, they must bear the additional hardware cost of DDR.
❌ To reduce BOM cost, they must forgo Linux and choose an RTOS with more limited resources and system capabilities.

Is it possible to break free from DDR constraints and use lower-cost, more highly integrated PSRAM to support a practical Linux solution?

Realtek has provided an engineering answer on the same Ameba SoC hardware platform: with only 8MB of PSRAM, the system can boot Linux, enter user space, and maintain a stable Wi-Fi connection.

Through detailed memory planning, system-level trimming, and hardware-software co-optimization, Realtek has opened a lower-barrier path into the Linux ecosystem for cost-sensitive, resource-constrained lightweight IoT devices.

Solution Architecture: From Hardware Foundations to Linux Runtime

A Linux system that runs correctly requires, at a minimum, the following foundations:

A processor architecture that supports Linux;
MMU and virtual memory capabilities;
Sufficient runtime memory;
A complete boot chain;
An adapted Linux kernel and RootFS;
Memory management mechanisms;
Basic peripheral drivers.

Making Linux run reliably on capacity-limited PSRAM is far more than simply replacing a hardware component or changing a few configuration options. The entire solution requires deep hardware-software collaboration to establish a complete, closed-loop system execution path.

01 Hardware Foundation: Ameba SoC Platform

This solution is based on the same hardware platform, RTL8730E. No external replacement of the runtime memory device is required. Different configurations reuse the same core architecture, while the chip’s heterogeneous multicore processing capability, Wi-Fi functionality, and complete set of peripheral resources remain unchanged.

High-performance processor: The dual-core Arm Cortex-A32 runs at 1.2GHz and integrates a hardware MMU, providing the virtual memory and address-isolation capabilities required by Linux.
Dedicated PSRAM controller: Handles PSRAM initialization, timing configuration, and address mapping, reliably integrating PSRAM into the system memory access path.
Cache and high-speed bus: Provides hardware acceleration for Flash XIP execution and runtime data access, serving as the hardware prerequisite for the division of responsibilities between Flash and PSRAM.

💡 The RTL8730E family offers a broad product matrix. Under the same core chip architecture, different memory configurations are integrated at the factory, covering product selections ranging from different PSRAM capacities to different DDR capacities.

02 Software Foundation: Linux Software Stack

A complete Linux software stack consists of four coordinated modules: the boot chain, kernel, RootFS, and user space. Each module determines whether the system can run reliably on constrained hardware:

Boot chain: Initializes the hardware and establishes the memory environment, connecting the kernel, RootFS, and device configuration.
Linux kernel: Handles MMU-based virtual memory management, process scheduling, the file system, the network protocol stack, and device-driver support.
RootFS: Provides the Shell environment, basic commands, system services, and network utilities that form the foundation for user-side operation.
User space: Hosts upper-layer applications, as well as Wi-Fi connection and control workflows.

💡 The PSRAM solution cannot directly reuse the complete software package of the DDR solution. Its core approach is to reassign storage for code, read-only resources, and writable data according to the limited runtime memory, while retaining the core system capabilities required by the product.

03 Runtime Mechanism: Flash XIP

Under the resource constraints of 8MB of PSRAM, simply trimming feature modules is not enough. The real breakthrough lies in redefining the responsibilities of Flash and PSRAM, allowing them to perform distinct, complementary roles.

Flash: Stores boot components, program code that supports XIP execution, and various static read-only resources.
PSRAM: Hosts page tables, stacks, writable data, driver state, DMA buffers, and dynamic Linux runtime data.

XIP (Execute In Place) means that the CPU directly executes code stored in Flash through address mapping and Cache acceleration, without first copying it to PSRAM.

The core value of XIP is that it reduces the amount of PSRAM occupied by code and read-only resources, leaving more space for the runtime data that Linux must read and write dynamically. This is a key software technique that enables Linux to run with 8MB of PSRAM.

Linux SDK: Core Adaptation and Trimming Work

The Linux SDK is a complete development kit for the Ameba SoC platform. It integrates the boot chain, Linux kernel, BSP and device drivers, RootFS, compiler toolchain, build system, and development documentation, covering the complete workflow from low-level system adaptation and image building to upper-layer application development.

To implement a stable Linux environment and Wi-Fi connectivity on 8MB of PSRAM, the solution requires system-level restructuring around storage allocation, code execution modes, the boot chain, component selection, and runtime memory consumption. The core adaptation and trimming work in the Linux SDK includes:

Memory layout and XIP planning
Boot-chain and kernel adaptation
RootFS and user-space trimming
Wi-Fi subsystem adaptation

💡 The current Linux SDK focuses on the Linux kernel, basic user space, and Wi-Fi connectivity. The specific available components are subject to the configurations and documentation provided with the SDK.

Runtime Verification: Measured Linux and Wi-Fi Results

On the RTL8730E hardware platform, Realtek has established a complete path from the boot components and Linux kernel to RootFS mounting. The system can enter user space successfully, allowing developers to log in through the serial port and inspect kernel logs, memory usage, and network status.

With Linux running stably, the Wi-Fi driver has also been fully adapted. Core workflows—including hotspot scanning, AP connection, automatic IP address acquisition through DHCP, and basic TCP/UDP network communication—have been verified.

The measured results are as follows:

Test Item	Measured Result
Hardware platform	RTL8730E
PSRAM configuration	8MB
SPI NOR Flash configuration	16MB
Official total image size	9876.2KB
Linux kernel version	6.18.24
RootFS type and size	CramFS, 5252KB
Power-on to Linux boot time	1.7s
Available memory after boot	4188KB
Wi-Fi band and mode	2.4GHz / 5GHz Wi-Fi STA
Wi-Fi TCP/UDP throughput	UDP: 87.4Mbps; TCP: 75.4Mbps

✅ Measured conclusion: On the 8MB PSRAM hardware platform, the Linux system and basic Wi-Fi connectivity have completed end-to-end engineering verification.

💡Note: Throughput is affected by the AP environment, channel, distance, test tools, and other conditions. The figures in the table are measured data from a specific laboratory environment and do not constitute a performance commitment for mass production.

The Ameba Linux Solution Portfolio: Covering All IoT Product Tiers

Ameba Linux offers more than just the engineering-grade 8MB PSRAM solution.

Based on the same hardware platform and a unified software framework, Realtek also provides multiple memory configurations ranging from lightweight PSRAM to high-capacity DDR, covering applications from resource-constrained devices and connected terminals to high-performance IoT products.

✅ 8MB PSRAM solution: Retains core Linux and Wi-Fi capabilities through Flash XIP, memory layout planning, and SDK trimming. It is suitable for lightweight IoT devices, connected terminals, and resource-constrained products.
✅ 16MB PSRAM solution: Maintains the integrated PSRAM form factor and high level of system integration while providing additional space for IoT products that require a larger user space and more runtime resources.
✅ DDR solution: Leverages greater memory capacity and bandwidth to support a more complete Linux software ecosystem, more complex application combinations, and higher-load data processing tasks.

The PSRAM solution is not a complete replacement for the DDR solution. Together, they form the complete Ameba Linux portfolio: customers do not need to make a single trade-off among the Linux ecosystem, system capabilities, and hardware cost. They can select the appropriate memory configuration and software profile according to their product requirements.

Development Resources: Source Code, Documentation, and Getting Started

The Linux SDK source code is now fully available!

Developers can access the source code and official documentation directly to quickly build images, flash development boards, boot the system, and test Wi-Fi connectivity, making it easy to get started with lightweight Linux IoT development.

📟 Hardware platform: RTL8730E
💻 Linux SDK: GitHub repository
📖 Online documentation: Ameba Linux SDK Documentation
🛒 Development board purchase: https://aiot.realmcu.com/zh/center/hardware/?tags=5%2C61&tags=5%2C35

Developers are invited to validate the solution, provide feedback, and help explore new Linux IoT solutions that deliver high integration, low cost, and a lightweight footprint.