Linux Kernel Boot Process in Depth

Embedded Linux & Multimedia · 40 illustrated lessons (text/HTML)

Outcomes

• Trace the kernel from bootloader hand-off to the first user process
• Explain how subsystems (memory, time, devices, PCI, USB) come up
• Diagnose boot failures on embedded platforms

Where we teach this

• EMB-201 · U-Boot Porting & Board Bring-Up live cohort
• KRN-101 · Kernel Architecture, Build & Modules live cohort

The lessons

Every lesson in this curriculum, in the order we teach it.

• 1Overall architecture of the boot process
• 2Bootloader-to-kernel hand-off
• 3Stage 1
• 4Architecture-specific initialisation
• 5The kernel decompression process in depth
• 6The start_kernel() function
• 7Trap and interrupt initialisation
• 8Early memory-management initialisation
• 9Processor-specific initialisation
• 10Console subsystem initialisation
• 11Time-subsystem bring-up
• 12Process-management subsystem bring-up
• 13Full memory-management initialisation
• 14VFS initialisation
• 15Device-model initialisation
• 16Block-device subsystem bring-up
• 17Character-device initialisation: terminal and serial drivers
• 18Network subsystem bring-up
• 19Module-subsystem initialisation
• 20ACPI subsystem bring-up in depth
• 21PCI subsystem initialisation
• 22USB subsystem bring-up
• 23File-system initialisation
• 24Security subsystem bring-up
• 25Creating kernel threads
• 26Softirqs and task queues
• 27RCU initialisation: setting up read-copy-update
• 28The performance monitoring subsystem
• 29Device-tree parsing
• 30Firmware interface initialisation
• 31Virtualisation support during boot
• 32Container-support initialisation
• 33Power-management bring-up
• 34Debug-subsystem initialisation
• 35Kernel parameter handling
• 36initramfs handling
• 37Preparing the switch to user space: root filesystem switch and running init
• 38System-call initialisation
• 39Signal-handling initialisation
• 40Boot completion and summary