Tagged
#x86
8 posts
You Can Boot It in Your Browser Now
The real 64-bit kernel — not a screenshot, not a screen recording — running live in a tab you can click. What that took, and the two bugs that had been hiding in plain sight until I moved the specimen to a new enclosure.
ReadThe confused deputy
I planted a flag on a kernel-only page and wrote a ring-3 program to steal it. The CPU stopped the direct read cold — then my own syscall handed the flag over the moment it dereferenced a caller-chosen pointer. The one door the hardware cannot guard for you.
ReadThe first wall
Ring 3, a syscall gate, and the two bits that turn 'the kernel is the only program' into 'the kernel runs code it doesn't trust.' The first time in this project that the hardware, not my kernel's goodwill, holds code back.
ReadIt has a prompt now
My from-scratch kernel runs its first interactive program: a shell, spawned as an ordinary task on the scheduler. The keyboard interrupt shrinks to 'enqueue one byte and return' — and the 'interactive code can't be tested' excuse falls apart.
ReadMultiple things at once, sort of
I gave my from-scratch kernel a timer and its first scheduler. Two tasks take turns on one CPU — first politely, then by force — and the preemption step turned out to be a concurrency trap wearing a simple mechanism's face.
ReadIt Listens Now
Milestone 5 of my from-scratch Rust kernel: PS/2 keyboard input — the first time the machine reacts to the outside world instead of just talking at it. Remapping the PIC, enabling interrupts for the very first time, and learning why forgetting one EOI makes the keyboard die after exactly one keypress.
ReadTeaching It to Fail Gracefully
Milestone 4 of my from-scratch Rust kernel: the IDT and exception handling — where the machine stops silently rebooting on a mistake and starts telling me what went wrong. The whole thing lives or dies on assembly and Rust agreeing about the shape of the stack.
ReadSetting Up to Build Nothing
I'm building an x86-64 operating system from scratch in Rust, and this is milestone zero: a toolchain and an empty kernel that compiles for a machine that isn't my machine. No boot, no output — just the unglamorous groundwork where most OS projects quietly die.
Read