From af1089a4262414b64714b87180f2223c8a40918f Mon Sep 17 00:00:00 2001 From: Natasha Moongrave Date: Wed, 8 Apr 2026 16:40:09 +0200 Subject: [Phase 2.1] GDT user space segments + heap growth MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit - Restructure GDT to add kernel_data/user_data/user_code in the order required for SYSCALL/SYSRET ABI: 0x08 kernel code, 0x10 kernel data, 0x18 user data, 0x20 user code, 0x28 TSS STAR MSR values: STAR[47:32]=0x08, STAR[63:48]=0x10 - Add TSS.privilege_stack_table[0] (RSP0) with 8 KiB static initial stack for Ring3→Ring0 hardware interrupt transitions - Expose GDT static and all Selectors fields as pub (needed by syscall module) - Add set_kernel_stack(VirtAddr) for scheduler to update RSP0 per-process - Grow HEAP_SIZE 100 KiB → 4 MiB to support process table + kernel stacks - Fix pre-existing lifetime elision lint in allocator.rs - Update flake.nix: add cpio, busybox, gdb, binutils, e2fsprogs - Update NOTES.md with decisions and next steps Co-Authored-By: Claude Sonnet 4.6 --- CLAUDE.md | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) (limited to 'CLAUDE.md') diff --git a/CLAUDE.md b/CLAUDE.md index d931abe..6a5aa38 100644 --- a/CLAUDE.md +++ b/CLAUDE.md @@ -4,7 +4,7 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co ## Project Overview -**Strix OS** is a bare-metal x86-64 operating system kernel written in Rust, aiming for Linux application compatibility. Currently in Phase 0-1 (foundational infrastructure). +**Strix OS** is a bare-metal x86-64 operating system kernel written in Rust, aiming for Linux application compatibility. Currently in Phase 1 (memory management complete, heading into user space). ## Build Commands @@ -45,13 +45,18 @@ cargo clean | `gdt.rs` | Global Descriptor Table + Task State Segment (double-fault stack) | | `interrupts.rs` | IDT setup, exception handlers, hardware interrupts (timer/keyboard via PIC 8259) | | `memory.rs` | Page table access (`OffsetPageTable`), `BootInfoFrameAllocator` for physical frames | +| `allocator.rs` | Heap allocator dispatcher; `HEAP_START`/`HEAP_SIZE` constants; `init_heap()` | +| `allocator/bump.rs` | Simple bump allocator (fast alloc, dealloc only when all freed) | +| `allocator/linked_list.rs` | First-fit linked-list allocator (arbitrary alloc/dealloc) | +| `allocator/fixed_size_block.rs` | **Active**: hybrid fixed-size block allocator with 9 size classes (8–2048 bytes) + linked-list fallback | | `vga_buffer.rs` | VGA text mode (80x25), `print!`/`println!` macros | | `serial.rs` | UART 16550 serial output, `serial_print!`/`serial_println!` for debugging | ### Memory Model -- Uses bootloader's `map_physical_memory` feature: all physical memory mapped at a fixed offset +- Uses bootloader's `map_physical_memory` feature: all physical memory mapped at a fixed offset (`0x0000256000000000`) - `OffsetPageTable` translates virtual ↔ physical addresses - `BootInfoFrameAllocator` provides frames from bootloader's memory map +- Heap region: virtual address `0x4444_4444_0000`, size 100 KiB ### Test Framework - Custom `#[test_case]` attribute with `Testable` trait @@ -74,7 +79,7 @@ cargo clean ## Roadmap -See `roadmap.md` for the 6-phase development plan. Next priorities: -1. Heap allocator (GlobalAlloc implementation) -2. User space (Ring 3 transition, syscall interface) +See `roadmap.md` for the 6-phase development plan. Phase 1 (memory management) is complete. Next priorities: +1. User space (Ring 3 transition, syscall interface via SYSCALL/SYSRET MSRs) +2. ELF loading (parser + execve) 3. Process management (fork, exec, scheduler) -- cgit v1.2.3