Exceptional Kernel Engineering - Bootstrapping the Machine: From UEFI/BIOS to Ring 0

I wrote this book to explain, with engineering precision, what actually happens between reset and your first line of C in ring 0. Most operating systems texts start after the hard part. I start at power-on and make early boot a tractable, testable sequence. I show how firmware prepares the stage, what guarantees the CPU makes, and what invariants you must establish before higher level subsystems can exist.You will see how to choose and configure a cross toolchain, how linker scripts shape memory layout, and how a small assembly shim hands control to a freestanding C runtime. I walk through CPU modes, segmentation artifacts that still matter, and the clean path into 64-bit long mode. I build a practical model for interrupts and exceptions, set up the IDT, map timers and time sources, and explain when to retire legacy mechanisms. I approach paging as a data structure problem, clarifying identity maps, higher-half layouts, and flags like NX, global, and PCID. I include a careful treatment of memory discovery via E820 and UEFI maps, early allocation strategies for stacks and page tables, and defensively designed boot protocols that keep handoff data precise and versionable.I keep the tone pragmatic. Each step is tied to a reason you can verify with QEMU, GDB, CPUID, and MSRs. I prefer small, composable building blocks over monoliths, so you always know what is initialized, what is safe to call, and what could fault. I maintain a strict freestanding C mindset, explain the safe subset to use, and avoid surprises hidden in compiler defaults.This book is for systems programmers, embedded engineers, and curious developers who want to design kernels from first principles. If you are comfortable with C and willing to read a little assembly, you will leave with a reliable bootstrapping playbook and the confidence to expand it. Read more