Comprehensive Overview of Embedded Interview Topics, Web Server Basics, TCP/IP Model, Linux Memory Management, and IPC

1. Self‑Introduction

The author introduces themselves, highlighting a strong interest in embedded systems, academic background in embedded principles, architecture, and development methods, as well as practical project experience designing embedded control systems and sensor networks, emphasizing problem‑solving skills and teamwork.

2. Huawei Internship Project

Briefly mentioned (details omitted).

3. Web Server Introduction and Challenges

Web servers deliver documents to browsers and host website files. They operate via HTTP, handling client requests and responding with appropriate content types.

Major products include Apache (open‑source, highly configurable), Nginx (high‑performance, event‑driven, suitable for high concurrency), and Microsoft IIS (integrated with Windows Server, offering robust management features).

Key challenges are concurrent request handling, security protection against attacks (DDoS, SQL injection, XSS), performance optimization (hardware, configuration, caching), log management and analysis, and compatibility across diverse client environments.

4. TCP/IP Four‑Layer Model

The model consists of Link Layer, Internet Layer, Transport Layer, and Application Layer, each providing distinct networking functions.

Link Layer: Handles physical media transmission, MAC addressing, and conversion between binary streams and electrical signals.

Internet Layer: Uses IP addressing and routing to deliver packets, handling fragmentation and reassembly.

Transport Layer: Provides end‑to‑end communication via TCP (reliable, connection‑oriented) and UDP (unreliable, low‑latency).

Application Layer: Hosts protocols such as HTTP, FTP, and SMTP, enabling user‑level network services.

5. Three‑Way Handshake

The TCP three‑way handshake establishes a reliable connection by exchanging SYN and ACK flags to synchronize sequence numbers and confirm both sides are ready for data transfer.

6. Graduate Project Overview

Briefly mentioned (details omitted).

7. Linux Memory Management

Linux uses virtual memory, dividing physical memory into ZONE_DMA, ZONE_NORMAL, and ZONE_HIGHMEM. User space provides separate virtual address spaces with code, data, BSS, heap, and stack segments.

Memory allocation uses brk for small (<128 KB) requests and mmap for larger allocations, with corresponding deallocation via free , munmap , or the allocator.

Monitoring tools include free , top , vmstat , sar , /proc/meminfo , pmap , GNOME System Monitor, and atop .

8. malloc Allocation Process

For allocations <128 KB, brk expands the data segment, allocating virtual space first; physical pages are committed on first access via page faults. For larger allocations, mmap reserves independent memory regions, initialized to zero, which can be released individually.

9. Process vs. Thread Communication

Process communication methods include pipes, message queues, shared memory, semaphores, and sockets, each with distinct characteristics and typical use cases.

Thread communication methods include shared variables (protected by locks), message passing, and condition variables for synchronization.

10. Business Introduction

Briefly mentioned (details omitted).