Embedded Linux Interview Questions and Answers

This article provides a list of questions and answers related to Embedded Linux. This questionnaire will help you prepare for job interviews for various Embedded Linux skill-based positions, as well as be useful during vivas for engineering students.

Embedded Linux Questions and Answers

Question - 1 : What is Embedded Linux, and where is it used?

Answer - 1 : Embedded Linux is a lightweight, customized version of the Linux operating system designed to operate on embedded devices. It is widely used in applications such as automotive systems, smart home devices, routers, industrial automation, and medical devices due to its flexibility, scalability, and open-source nature.

Question - 2 : What are the advantages of using Linux in embedded systems?

Answer - 2 : Following are the advantages of using Linux:

• Open-source: Reduces cost and allows customization.
• Scalability: Can run on various hardware platforms.
• Rich ecosystem: Wide range of tools, libraries, and applications.
• Stability and security: Well-tested and supported by a large community.
• Real-time support: Available through patches like PREEMPT_RT.

Question - 3 : What is the difference between Embedded Linux and a traditional Linux distribution?

Answer - 3 : The following table highlights the key differences:

Question - 4 : What is a bootloader in Embedded Linux? Name a few examples.

Answer - 4 : A bootloader is a small program that initializes the hardware and loads the operating system kernel into memory during the boot process. Examples include:

• U-Boot (Universal Boot Loader)
• GRUB (GNU GRUB)
• Barebox

Question - 5 : What is the role of the Linux kernel in an embedded system?

Answer - 5 : The Linux kernel provides essential functionality, such as:

• Hardware abstraction through device drivers.
• Process and memory management.
• File system support.
• Networking capabilities.
• Real-time scheduling when patched with PREEMPT_RT.

Question - 6 : What are some commonly used file systems in Embedded Linux?

Answer - 6 :

• ext3/ext4: Journaling file systems suitable for larger storage.
• JFFS2 (Journaling Flash File System 2): Designed for NOR flash memory.
• YAFFS2 (Yet Another Flash File System): Suitable for NAND flash.
• SquashFS: Read-only, highly compressed file system for embedded devices.

Question - 7 : How do you debug an Embedded Linux application?

Answer - 7 :

• GDB (GNU Debugger): For debugging applications.
• strace: To trace system calls and signals.
• valgrind: For memory analysis and debugging.
• Log files: Reviewing system logs using tools like dmesg & /var/log.
• Serial Debugging: Using a serial port to log outputs from the bootloader or kernel.

Question - 8 : What is a Device Tree in Embedded Linux?

Answer - 8 : The Device Tree (DT) is a data structure for describing the hardware components of a system. It tells the Linux kernel how the hardware is configured. The DT is typically stored in a file with a .dts extension and compiled into a .dtb binary.

Question - 9 : What tools are used to build Embedded Linux?

Answer - 9 :

• Buildroot: A simple tool to build root file systems and kernels.
• Yocto Project: A more complex and flexible build system for creating custom Linux distributions.
• Cross Compilers: Tools like GCC or Clang to compile code for the target architecture.

Question - 10 : How do you achieve real-time performance in Embedded Linux?

Answer - 10 :

• Use a real-time kernel patch like PREEMPT_RT.
• Optimize interrupt handling and kernel preemption.
• Avoid using high-latency operations like disk I/O during critical processes.
• Set real-time priorities for critical threads using tools like chrt.
• Use specific real-time libraries such as RTLinux or Xenomai.