Shikimori's Not Just a Cutie!

[zen-zap]

So this one includes some significant changes.

The first would be the separation of kernel and builder. Besides this, there are additional parameters added to the GDT along with a change in text mode.

Major Changes:

• Migrated to Bootloader v0.11.15
• UEFI does not support pic8259. So removed that as dependency and used apic for interrupt handling
• memory allocation uses bitmap, this allows for reuse for frames
• print uses the framebuffer provided by the new bootloader crate (no longer VGA)

Minor changes:

• the fs commands held locks during operation, fixed them
• interrupt changes according to APIC
• some groundwork and looked in to kernel and user ring separation
• removed the test harness (it was too big and I can't test everything I write)
• CI pipeline works now .. just builds .. nothing more (just nice to see ci)
• target was changed to x86_64-unknown-none
• force-frame-pointers for debug. the panic shows good info with llvm-addr2line

Also planned to improve virtio operations in this one. But, I found some things to do in my filesystem as well so interrupt driven virtio and filesystem changes will be for another time.

Also planning syscalls for that privilege separation thingy. Let's see. Whichever one I learn first goes in the next PR.

This is how it looks now:

[zen-zap]

Let me request a review from copilot .. let's see what it says.

[Copilot]

Pull request overview

This PR performs a major repo restructure and platform migration for the OS: it splits the project into a workspace (kernel + builder), migrates to bootloader_api v0.11.15, replaces legacy PIC-based interrupts with ACPI/APIC wiring, moves output from VGA text mode to a framebuffer-backed console, and introduces a bitmap-based physical frame allocator.

Changes:

• Converted the repo into a workspace with a new kernel crate and a builder orchestration binary (replacing the prior single-crate layout and custom target JSON).
• Migrated boot/runtime integration to bootloader_api v0.11.15, added framebuffer printing, and updated build/CI configuration for x86_64-unknown-none.
• Reworked low-level subsystems: ACPI/APIC interrupt path, bitmap frame allocator, and filesystem init refactor.

Reviewed changes

Copilot reviewed 52 out of 63 changed files in this pull request and generated 10 comments.

Show a summary per file

File	Description
x86_64-blog_os.json	Removed custom target JSON (now using x86_64-unknown-none).
rust-toolchain.toml	Fixed toolchain component name (rustfmt).
rust-analyzer.toml	Updated rust-analyzer target to x86_64-unknown-none.
README.md	Updated project overview and build/run instructions for the new workspace/builder flow.
Cargo.toml	Converted root crate into a workspace (kernel, builder) and adjusted profiles.
Cargo.lock	Updated lockfile for new workspace crates and dependencies (bootloader_api, acpi, etc.).
.cargo/config.toml	Set force-frame-pointers rustflags for target_os = none builds.
.github/workflows/build.yml	Reworked CI to build kernel + builder and do a basic boot run in QEMU.
.vscode/settings.json	Updated rust-analyzer settings and added cSpell words.
.idea/vcs.xml	Updated IntelliJ VCS mapping (currently includes user-specific path).
.idea/modules.xml	Updated IntelliJ module reference (now points to creo.iml).
.gitignore	Simplified ignore list (removed some previously ignored local files).
builder/Cargo.toml	Added new builder crate depending on bootloader 0.11.15.
builder/src/main.rs	Added orchestrator: builds kernel, produces BIOS/UEFI images, runs QEMU.
kernel/Cargo.toml	Added creo kernel crate with new dependencies (bootloader_api, acpi, framebuffer font).
kernel/.cargo/config.toml	Kernel-local target + build-std configuration for x86_64-unknown-none.
kernel/src/main.rs	New kernel entrypoint using bootloader_api, framebuffer init, APIC init, FS init, executor run.
kernel/src/lib.rs	New kernel library root, module exports, globals, init/hlt/exit-qemu.
kernel/src/acpi.rs	Added ACPI handler implementation for mapping physical tables via the bootloader offset.
kernel/src/apic.rs	Added ACPI/APIC init (disables PIC, enables Local APIC, programs I/O APIC for IRQ1).
kernel/src/interrupts.rs	New IDT + APIC EOI logic; IRQ vectors defined without legacy PIC.
kernel/src/gdt.rs	Updated GDT/TSS with ring0/ring3 selectors + RSP0 and IST setup.
kernel/src/memory.rs	Migrated memory map plumbing to bootloader_api and added bitmap frame allocator + user page mapping helper.
kernel/src/allocator.rs	Switched to fixed-size block allocator as global allocator (plus refactors/comments cleanup).
kernel/src/allocator/bump.rs	Added bump allocator implementation.
kernel/src/allocator/linked_list.rs	Added linked-list allocator implementation.
kernel/src/allocator/fixed_size_block.rs	Added fixed-size block allocator implementation with fallback heap.
kernel/src/framebuffer.rs	Added framebuffer-backed text rendering and integrated it into printing path.
kernel/src/print.rs	Added exported print!/println! macros targeting the framebuffer printer.
kernel/src/serial.rs	Formatting/cleanup of serial printing implementation.
kernel/src/scanc.rs	Added scancode-to-string helper (legacy/testing).
kernel/src/task/mod.rs	Added user task module and updated task module exports.
kernel/src/task/executor.rs	Updated executor: added idle sleep and waker constructor rename.
kernel/src/task/simple_executor.rs	Added a minimal FIFO executor implementation.
kernel/src/task/keyboard.rs	Added async scancode stream + helpers for shell/key tasks.
kernel/src/task/user.rs	Added inline-asm transition helper for entering ring 3.
kernel/src/shell/mod.rs	Reordered/updated shell module exports.
kernel/src/shell/shell_task.rs	Added async shell task with basic commands and FS command dispatch.
kernel/src/shell/fs_com.rs	Added async filesystem command helpers that release locks before printing.
kernel/src/shell/basic_com.rs	Added placeholder basic command module.
kernel/src/fs/mod.rs	Added filesystem module and updated FS module exports.
kernel/src/fs/filesystem.rs	Added filesystem initialization helper (VirtIO mount/format + optional self-check).
kernel/src/fs/block_dev.rs	Minor import reordering.
kernel/src/fs/simple_fs.rs	Multiple cleanups/refactors, minor behavior changes, and formatting improvements.
kernel/src/fs/layout.rs	Formatting/comment tweaks in on-disk layout definitions.
kernel/src/utils/tracing.rs	Updated crate naming in tracing docs.
kernel/src/utils/mod.rs	Reintroduced utils::tracing module for the kernel crate.
kernel/src/virtio/mod.rs	Switched VirtIO to use bitmap frame allocator and updated global allocator plumbing.
kernel/src/virtio/pci.rs	Reduced/cleaned PCI scan logging and kept VirtIO vendor scan.
kernel/src/vga_buffer.rs	Redirected print!/println! away from VGA text mode toward serial output (VGA tests removed).
src/main.rs	Removed legacy single-crate kernel entrypoint (now kernel/src/main.rs).
src/lib.rs	Removed legacy library root (now kernel/src/lib.rs).
src/interrupts.rs	Removed legacy PIC-based interrupt code (replaced by APIC-based kernel module).
src/gdt.rs	Removed legacy GDT implementation (replaced by kernel’s updated GDT).
src/task/keyboard.rs	Removed legacy async keyboard module (moved into kernel crate).
src/shell/shell_task.rs	Removed legacy shell task (moved into kernel crate).
src/shell/fs_com.rs	Removed legacy FS command module (replaced with async version in kernel crate).
src/utils/mod.rs	Removed legacy utils module stub (now kernel/src/utils/mod.rs).
tests/basic_boot.rs	Removed integration test (test harness removed per PR description).
tests/heap_allocation.rs	Removed integration test (test harness removed per PR description).
tests/should_panic.rs	Removed integration test (test harness removed per PR description).
tests/stack_overflow.rs	Removed integration test (test harness removed per PR description).

Files not reviewed (2)

• .idea/modules.xml: Language not supported
• .idea/vcs.xml: Language not supported

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[Copilot]

notify_apic_eoi hard-codes the Local APIC base to 0xfee00000, but apic::init reads the actual local_apic_address from ACPI. If the Local APIC isn’t at the default address, EOI will be written to the wrong MMIO location and interrupts can stop working. Consider storing the detected Local APIC physical address (or virtual base) in a global and using it here instead of a constant.

[Copilot]

File header says in kernel/src/shell_task.rs, but this is kernel/src/shell/fs_com.rs. This is misleading when navigating the code; update the module-level doc comment to match the actual path/module.

[Copilot]

Unused imports (alloc::vec::Vec and spin::Mutex) appear to be left over here. Removing them will keep this module tidy and avoid relying on crate-level #![allow(unused)] to hide warnings.

[Copilot]

UEFI boot uses -bios OVMF.fd, but this file is not in the repository and likely won’t exist on CI/other dev machines. This makes cargo run --bin builder fail in UEFI mode by default. Consider either (1) using the distro OVMF path (e.g., /usr/share/OVMF/OVMF_CODE.fd on Ubuntu), (2) making the path configurable via env/CLI flag, or (3) defaulting to BIOS unless an OVMF path is provided.

[zen-zap]

this

[Copilot]

The Swatinem/rust-cache@v2 step is duplicated (same name and action at lines 28-30 and 38-39). This is redundant and can be removed to shorten CI time and reduce confusion.

Suggested change

	- name: Cache Cargo Registry and Build
	uses: Swatinem/rust-cache@v2

[Copilot]

This adds a user-specific IntelliJ VCS mapping ($USER_HOME$/Code/creo). Committing machine-specific IDE paths makes the repo noisy and can confuse other developers. Consider removing this mapping (and ideally excluding .idea/ from version control) or keeping only project-relative mappings.

Suggested change

<mapping directory="$USER_HOME$/Code/creo" vcs="Git" />

[Copilot]

enter_user_mode binds code_selector/data_selector as u16 into 64-bit registers (rdi/cx) and then pushes rcx/rdi. With u16 operands the compiler may only write di/cx, leaving the upper bits of rdi/rcx undefined when doing 64-bit push instructions. It’s safer to explicitly zero-extend to 64-bit before pushing (e.g., pass selectors as u64 into rcx/rdi, or add movzx in the asm).

[Copilot]

sivr |= 0x100 | 0xFF sets the Local APIC spurious interrupt vector to 0xFF, but there is no IDT handler installed for vector 0xFF. If a spurious interrupt is delivered, this can lead to an unhandled interrupt (and potentially a double/triple fault). Consider picking a dedicated vector that has an IDT entry (and implementing a minimal spurious handler that just EOIs/returns).

Suggested change

	unsafe {
	let mut sivr = core::ptr::read_volatile(sivr_ptr);
	sivr |= 0x100 | 0xFF;
	const APIC_SIVR_SOFTWARE_ENABLE: u32 = 0x100;
	unsafe {
	let mut sivr = core::ptr::read_volatile(sivr_ptr);
	// Preserve the currently configured spurious interrupt vector here.
	// A dedicated vector should only be programmed once an IDT entry exists for it.
	sivr |= APIC_SIVR_SOFTWARE_ENABLE;

[zen-zap]

mmmmmmm ...

[Copilot]

set_pixel uses if offset + 2 < framebuffer.len() for all pixel formats, but for PixelFormat::U8 you only write a single byte at offset. This overly-strict bounds check can skip valid pixels near the end of the buffer in U8 mode. Consider making the bounds check depend on bytes_per_pixel/pixel format (e.g., require offset < len for U8, offset + 2 < len for RGB/BGR, etc.).

Suggested change

	if offset + 2 < self.framebuffer.len() {
	// offset + 2 since we writing 3 separate bytes into the 1D array of framebuffer
	match self.info.pixel_format {
	PixelFormat::Rgb => {
	self.framebuffer[offset] = r;
	self.framebuffer[offset + 1] = g;
	self.framebuffer[offset + 2] = b;
	},
	PixelFormat::Bgr => {
	self.framebuffer[offset] = b;
	self.framebuffer[offset + 1] = g;
	self.framebuffer[offset + 2] = r;
	},
	PixelFormat::U8 => {
	// Grayscale fallback
	let gray = (r as u32 + g as u32 + b as u32) / 3;
	self.framebuffer[offset] = gray as u8;
	},
	_ => {},
	}
	match self.info.pixel_format {
	PixelFormat::Rgb => {
	if offset + 2 < self.framebuffer.len() {
	// offset + 2 since we writing 3 separate bytes into the 1D array of framebuffer
	self.framebuffer[offset] = r;
	self.framebuffer[offset + 1] = g;
	self.framebuffer[offset + 2] = b;
	}
	},
	PixelFormat::Bgr => {
	if offset + 2 < self.framebuffer.len() {
	// offset + 2 since we writing 3 separate bytes into the 1D array of framebuffer
	self.framebuffer[offset] = b;
	self.framebuffer[offset + 1] = g;
	self.framebuffer[offset + 2] = r;
	}
	},
	PixelFormat::U8 => {
	if offset < self.framebuffer.len() {
	// Grayscale fallback
	let gray = (r as u32 + g as u32 + b as u32) / 3;
	self.framebuffer[offset] = gray as u8;
	}
	},
	_ => {},

[zen-zap]

our output is bgr if I'm correct ... not tested with other things

[Copilot]

.idea/modules.xml now references .idea/creo.iml, but the repo still contains .idea/blog_os.iml and no creo.iml. This mismatch can break IntelliJ project loading for others. Either add/rename the .iml accordingly or avoid committing IDE module files.

Suggested change

	<module fileurl="file://$PROJECT_DIR$/.idea/creo.iml" filepath="$PROJECT_DIR$/.idea/creo.iml" />
	<module fileurl="file://$PROJECT_DIR$/.idea/blog_os.iml" filepath="$PROJECT_DIR$/.idea/blog_os.iml" />