Code Wrangling at its Best
In Chapter 12, we added wait queues and blocking keyboard input: Now we need synchronization primitives that ordinary kernel code can use. This chapter adds: A mutex provides mutual exclusion: only one thread may hold the protected resource at a time. OSDev describes a mutex as a mutual-exclusion mechanism, similar to a binary semaphore, used
Continue Reading “Chapter 13 — Mutexes, Semaphores, and a Console Lock”
In Chapter 11, we added the first blocking primitive: That gave the scheduler a way to remove a thread from the ready queue until a future timer tick. Now we need a more general primitive: This is the foundation for real kernel I/O. A keyboard reader should not spin like this: It should block: This
Continue Reading “Chapter 12 – Wait Queues and Blocking Keyboard Input”
In Chapter 10, we added timer-driven preemption: Now we need the next scheduler capability: blocking. A runnable thread competes for CPU time. A blocked or sleeping thread does not. OSDev describes a blocking process as one that waits for an event, such as a semaphore or message, and is removed from the active scheduling queue
Continue Reading “Chapter 11 — Blocking Primitives, Sleep Queues, and Scheduler Hygiene”
In Chapter 4, we built the first memory-management layer: Now we add the next layer: paging. Paging lets the CPU translate a virtual address into a physical address through page tables. In 32-bit x86 paging without PAE, a virtual address is split into a page-directory index, page-table index, and page offset; page directories and page
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