1. Linux Kernel Internals

Importance:

Understanding kernel internals is crucial for BSP and driver development as it helps in debugging, optimizing performance, and modifying the kernel to meet hardware-specific requirements.

Topics:

  • Kernel Architecture: Monolithic vs Microkernel, Kernel and User Space interactions.
  • Process Management: Understanding task_struct, process states, scheduling algorithms.
  • Interrupt Handling: SoftIRQs, tasklets, bottom halves, handling IRQs efficiently.
  • Memory Management: Paging, kmalloc/vmalloc, slab allocator, ARM MMU and memory regions.
  • Syscalls: How system calls work, writing custom syscalls.
  • Kernel Synchronization: Spinlocks, mutexes, semaphores, barriers, RCU.
  • Workqueues and Timers: Deferred execution, using timers for scheduling tasks.

2. Linux Device Drivers

Importance:

Device drivers are the bridge between hardware and the OS. Understanding drivers is crucial for embedded systems and BSP development.

Topics:

  • Character Drivers: open(), read(), write(), ioctl() implementations.
  • Block Drivers: Block layer, request queues, I/O scheduling.
  • Platform Drivers: Registering platform devices, working with platform_driver.
  • Peripheral Drivers (I2C, SPI, UART, GPIO): Writing and debugging drivers.
  • Power Management: Implementing runtime PM, suspend/resume operations.
  • Interrupt Handling: Requesting IRQs, shared interrupts, threaded IRQs.
  • DMA Handling: Understanding DMA API, memory mappings.

3. Board Support Package (BSP) Development

Importance:

BSP development is fundamental in embedded systems as it enables the OS to run on custom hardware.

Topics:

  • Boot Process & Bootloaders: U-Boot configuration, boot sequence.
  • Device Tree (DTS/DTSI): Writing device tree files, overlays.
  • Kernel Configuration & Compilation: Using menuconfig, defconfig, Kconfig.
  • Root Filesystem & Init System: Understanding BusyBox, systemd integration.
  • Flash Storage Handling: MTD subsystem, eMMC, NAND, SPI-NOR.
  • Clock & Power Management: Configuring common clock framework, PMIC integration.