xv6 operating system kernel design from scratch in C program

Learn how spin locks and sleep locks protect shared data from race conditions in the xv6 kernel, covering initialization, acquisition, release, and how interrupt control prevents deadlocks.

Explore how xv6 sets up and uses multi-level page tables, satp, sv39 sv48 sv32, maps virtual memory to physical addresses, and manages memory allocation and freeing.

Map a process's memory by creating and growing its page table with UVM create and UVM alloc, then map, copy, and manage pages, including unmap and copy for fork.

Explain kernel virtual memory functions in xv6, including kvm init and work address, how uvm creates and maps process page tables, and how exec loads segments.

Explore how the platform level interrupt controller manages and multiplexes external interrupts, routes them to cores, and uses priority, enable, and threshold registers in xv6's interrupt design.

Set up trap handling by configuring supervisor and machine mode vectors and saving/restoring registers in the kernel trap. Implement timer interrupts, scheduling via yield, and sleep using ticks.

Map traps in user mode by using a trampoline and per-process trap frames, saving and restoring registers via user vec and user trap return, handling system calls and timer interrupts.

Explore virtio memory mapped io in xv6, enabling virtual disk i/o via memory mapped registers, feature negotiation, queues, and descriptors to access a host block device in qemu.

Explain how the kernel and host communicate for virtual disk I/O by using interrupt-driven reads/writes, a shared available/used ring, and descriptor buffers managed by the driver.

Explore how buffer management enables concurrent memory access through a circular doubly linked buffer cache with valid bits, ref counts, and disk io via bread and beget mechanisms.

Discover how the disk logging mechanism preserves consistency by buffering writes to a log block before updating data blocks, supporting recovery, begin op, end op, and commit handling.

Explore how xv6 maps memory blocks using bitmaps, detailing the superblock, inode and data blocks, and bitmap-based block allocation and indirect addressing.

Explore the inode-based file and directory structures in xv6, learn how blocks, direct and indirect addressing, and bitmaps enable accessing, reading, and updating inodes via directory lookup and bmap.

Explore the file system in xv6 kernel design, covering file structure, inodes, pipes, file table and operations: open, close, read, write, dupe, and stat, with locking.

Examine the xv6 pipe design, detailing a pipe structure with read and write pointers, a lock, and files created by pipe alloc for reading and writing, open and close semantics.

Explore how the xv6 kernel manages processes from init to zombie using procinit, allocproc, fork, reparent, and userinit, covering process states, context switching, and the scheduler.

Learn how to set up system calls in xv6 from user space via user.h, the 21 system calls, and the trap mechanism, including loading ELF programs with exec.