Embedded Linux · Kernel · FPGA · 5G/6G

An Engineer's Notebook: Embedded, Kernel, 5G/6G¶

Personal technical notes and short research articles on embedded Linux, the Linux kernel, programming, FPGA and wireless networking (5G/6G), written in both Vietnamese and English.

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128 notes9 topicssince 2019updated 2026-10-23

Quote by Paulo Coelho, the author of "The Alchemist"

Latest articles¶

Rockchip RK3399 secure eFuse: vì sao kernel Linux đọc vào là panic2026-10-22 · Embedded Linux

Secure boot cần một nơi lưu hash của root key mà không ai sửa được sau khi xuất xưởng. Trên SoC Rockchip, nơi đó là eFuse, và Linux không được phép đọc nó.

SpacemiT V100: CPU server RISC-V 46 core, tiến bộ về hiệu năng hay về chuẩn hóa?2026-10-22 · Embedded Linux

Ngày 19/10/2026, SpacemiT công bố V100, một CPU server RISC-V 46 core phát triển cùng nhóm XiangShan. Hãng cho biết đây là chip đầu tiên tuân thủ đầy đủ RISC-V Server…

Kiến trúc CPU thương mại 2026: x86, ARM, RISC-V và góc nhìn 5G RAN2026-10-21 · Embedded Linux

x86 vẫn dẫn server và PC, ARM thống trị mobile và đang vào server, còn RISC-V đi lên từ MCU sang AI và edge. Bài này tóm tắt ba kiến trúc chính, cách chúng được cấp…

All articles

Topics¶

Articles

Short research articles, one small topic per article.
Embedded

Petalinux, Yocto, U-Boot, PTP, DPDK and board projects.
Linux Kernel

Device drivers (I2C, SPI, GPIO, UART, ALSA) and kernel debugging.
Virtualization

Virtualization fundamentals, hypervisors (KVM, Hyper-V, Jailhouse), containers (Docker) and embedded use cases.
Wireless / RAN

5G/6G RAN: CU/DU/RU and splits, Open Fronthaul, PTP synchronization, L1 acceleration and the 6G roadmap.
Security

Threat model, CVE management, TLS / SSH, secure boot and TrustZone for embedded devices.
Programming

C, data structures, design patterns, perf, multi-threading, shell script and Python.
Chip & SoC

Computer architecture (ISA, microarchitecture, SoC) and IC design (RTL, FPGA, timing analysis, verification).
Notes

Book notes, bookmarks, Mkdocs and Markdown.

Document Tree¶

Embedded

Linux Embedded Overview: What an embedded Linux engineer does: bring-up, application and driver development, real-time optimization and security.
Hardware & Projects
- HW Platforms: List of hardware platforms used, such as Xilinx Zynq7000 and Zynq UltraScale+.
- Zynq: Projects on Zynq boards such as Zedboard and Picozed.
- i.MX6 (DART-MX6): DART-MX6 kit: hardware overview and Yocto build.
- IMX8: WIP – no content yet.
- Raspberry Pi 3B: Raspberry Pi 3 Model B links and notes on porting Linux.
Boot & Bring-up
- U-Boot on Zynq: Building U-Boot for Zynq7000 on Zedboard.
Build System
- Yocto
  - Yocto Overview: Yocto overview: Poky, layers, recipes and packages, the BitBake task flow, recipe syntax and handy commands.
- Xilinx Petalinux
  - Petalinux Overview: Overview of Xilinx Petalinux tooling for porting Linux to Zynq7000.
  - Petalinux 2017: Technical notes and tips from working with Petalinux 2017.4.
  - List of Petalinux Images: Table describing the image files Petalinux produces.
Application Dev
- Common Tools
  - Makefile: History, rules, phony and implicit targets, variables, pattern rules and advanced features of Makefile.
  - CMake: CMake build system generator: targets, modern CMake, and cross-compiling for embedded Linux.
  - Version Control Concept: Introduction to version control and popular client-server and distributed systems.
  - Git: Git commands: merging repositories, remotes, branches and commits, and syncing the master and dev branches.
Networking & Performance
- Linux PTP: Network synchronization with IEEE 1588 PTP and ITU-T G.8260 on Linux.
- DPDK: WIP – no content yet.
- Network Block Device: Introduction to and usage of Network Block Device for remote block storage.
Device & Peripherals
- EEPROM: Introduction to serial EEPROM devices and their characteristics.
Tips & Linux Basics
- Tips: Practical tips such as SSH options for remote control.
- Unsorted: Unsorted Linux notes such as update-rc.d and SUSv3.
- Commands: Handy Linux commands, e.g. xclip for copying to the clipboard.

Linux Kernel

Linux Kernel Overview: Overview of the kernel: kernel/user space, main components and subsystems.
Linux Device Driver
- LDD Overview: Overview of Linux Device Driver: device model, kernel modules, character devices and hardware access.
- Kernel Module: Kernel modules: module_init/exit, logging, installing and compiling a module, and dynamic debug.
- Character Device: Character device drivers: device files, major/minor numbers, mutex, mmap and ioctl.
- Platform Device: Platform devices in the Linux device model and how drivers get hardware resources (struct resource).
- I2C Subsystem: I2C bus and the Linux I2C platform driver model.
- SPI Device: Developing SPI device drivers in the Linux kernel.
- SPI Device Advance: Advanced SPI topics: extending chip-select signals and SPI GPIO (outline only).
- GPIO: The Linux GPIO subsystem from the driver perspective.
- UART: Serial (UART) programming in userspace with reference materials.
- JESD: WIP – no content yet.
- Audio: Audio in Linux: ALSA architecture and concepts.
- PCIe: WIP – no content yet.
Linux Kernel General
- Kernel Data Structure: Kernel data structures such as the list_head linked list.
- Kernel Space, User Space Interfaces: Reference link on kernel space and user space interfaces.
- FTrace: How to use ftrace to debug the kernel, from a real synchronization bug.
- Dynamic Debug: Enabling and disabling kernel debug messages at runtime with dynamic debug.
- Common Clock Framework: CCF architecture, consumer/provider API, Device Tree binding, locking with PREEMPT_RT, debugging and recent changes.

Virtualization

Overview: Virtualization levels, hypervisors and containers, VM vs container, micro-VMs and virtualization in embedded systems.
Foundations
- CPU Virtualization: Trap-and-emulate, VT-x/AMD-V/ARM EL2, VM exits and vCPU scheduling.
- Memory Virtualization: Shadow page tables vs nested paging (EPT, Stage-2), memory overcommit and IOMMU.
- I/O Virtualization: Emulation, virtio, VFIO passthrough, SR-IOV and interrupt virtualization.
Hypervisor
- Hypervisor & Hyper-V: Hypervisor types, Hyper-V architecture, Linux as root partition (mshv) and the boot sequence.
- KVM & QEMU: Roles of KVM and QEMU, the /dev/kvm API, x86 and ARM64 examples.
- Partitioning Hypervisor: Jailhouse, Xen and mixed-criticality partitioning on SoCs.
Container
- Container Internals: Namespaces, cgroups v2, capabilities, overlayfs and the OCI runtime flow.
- Docker: Docker concepts, running containers, container and image management, volumes and bind mounts.
- Docker Compose: Multi-container development environments with Compose.
Sandbox & micro-VM: Kata Containers, Firecracker and gVisor compared.
Real-time & vRAN
- Real-time KVM tuning: isolcpus/nohz_full, vCPU and emulator pinning, 1G hugepages, NUMA and cyclictest in the guest.
- vRAN on VM: SR-IOV VF for fronthaul, DPDK in the guest, PTP through VF and a deployment checklist.
Embedded Use Cases
- Docker for Build Environments: Sample Dockerfile and notes for Yocto/Petalinux build containers.
- QEMU Cross-Architecture: qemu-user, binfmt_misc and multi-platform container builds.

Wireless / RAN

Overview: Scope of the RAN topic, the CU/DU/RU picture, technical constraints and links to related topics.
RAN Architecture & Splits: NG-RAN blocks and interfaces, 3GPP split options and why O-RAN uses 7.2x.
Fronthaul & Sync
- Open Fronthaul: eCPRI, C/U/S/M planes, IQ compression, timing windows and the M-plane.
- Synchronization: Frequency and phase requirements, SyncE, PTP telecom profiles and O-RAN sync configurations.
L1 & Acceleration: PHY processing chain, lookaside and inline accelerators, DPDK BBDev and FAPI.
6G Roadmap: Standardization milestones, technical directions and impact on RAN architecture.

Security

Overview: Threat model of embedded devices, protection layers (boot, communication, vulnerability management) and topic map.
Vulnerability Management
- CVE: CVE and related standards (CWE, CPE, CVSS, EPSS, KEV, VEX), how CNAs, upstream and distros handle CVEs, and CVE management for embedded products with SBOM.
- InsightVM (Rapid7): Rapid7 InsightVM: connecting to target devices, scan workflow and vulnerability detection mechanism.
Cryptography & Transport Security
- TLS: TLS 1.3 protocol: architecture, handshake, HKDF key schedule, record protocol and cryptographic algorithms.
- SSH: Short introduction to SSH: three-layer architecture, connection flow, comparison with TLS and notes for embedded devices.
Secure Boot & Trusted Execution
- Secure boot và TrustZone: Basics of chain of trust, Root of Trust, TrustZone, Exception Levels, TF-A stages and OP-TEE, with a Rockchip example.

Programming

C
- C introduction: History and standards of the C language, libc and glibc.
- Compiling C: The C build pipeline: preprocessing, compilation, assembly and linking, static vs dynamic linking, cross compiling.
Data Structure & Algorithms
- Index: Table of contents of data structure and algorithm notes.
- Linked List: Doubly linked list implementation, using an example from CS144.
- Queue: Queue implemented with arrays and lists (outline only).
SQL: MySQL notes, currently only installation heading.
Linux Programming Interfaces: Points to the book The Linux Programming Interface.
Design Patterns: Top 10 embedded design patterns (hardware proxy, ISR, ring buffer, state machine, ...) and the Reactor/Active Object patterns.
Multi-threads: Link to Oracle's multi-threaded programming guide.
Perf: Using perf to monitor and record system performance events.
Shell Script: Shell script syntax: variables, arrays, arguments, conditions, loops, functions, input/output, redirection and pipes.
Python: Quick Python syntax notes: print formatting, lists and try/except.

Chip & SoC

Overview: Computer architecture and IC design: scope and how the two groups relate.
Computer Architecture
- ISA
  - Overview: Instruction set architecture overview (stub, RISC-V and ARM).
  - RISC-V: What RISC-V is: origin and governance, modular ISA structure, comparison with Arm and x86, pros and cons.
- Microarchitecture
  - Overview: How a CPU implements the ISA (stub).
  - Pipeline: Pipeline stages, hazards, branch prediction (stub).
  - Cache: Cache organization, policies, coherence (stub).
  - Memory Hierarchy: Registers to DRAM, locality, virtual memory (stub).
- SoC / System
  - Overview: System-level architecture of an SoC (stub).
  - RISC-V Server SoC Spec: Hardware requirements of the RISC-V Server SoC Specification v1.0 (AIA, IOMMU, PCIe, RAS, security) and a compliance checklist.
IC Design
- RTL / HDL
  - Overview: Describing hardware at RTL with Verilog/SystemVerilog (stub).
- FPGA
  - Overview: FPGA resources and tool flow (stub).
  - Xilinx IPCore: Xilinx IP core usage, e.g. configuring Clocking Wizard dynamically over AXI4-Lite.
- Static Timing Analysis: Basic definitions of static timing analysis and STA in Xilinx Vivado.
- Verification
  - Overview: Testbench, coverage, UVM, assertions and formal (stub).

Notes

Book & Materials
- C Programming: List of C programming books, including Head First C.
- Linux Programming: Linux books such as Linux in a Nutshell and The Linux Programming Interface.
- Linux Device Driver: Entry for the book Linux Device Drivers, 3rd edition.
- Linux Kernel: Entry for the book Understanding the Linux Kernel.
- Linux Embedded: Free Electrons slides on Embedded Linux kernel and driver development.
- Data Structure & Algorithms: Algorithms books by Robert Sedgewick (Algorithms 4th, Algorithms in C).
- Others: Other books, currently The Art of Computer Programming.
Bookmarks: Collection of useful Linux websites, blogs and tutorial series.
Mkdocs Tool: User guide for Mkdocs and how to publish it with Github Page.
Markdown Language: Markdown syntax used to write this documentation.
What's next: To-do list of topics to study and write about next.

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