Development

[assembler-0]

Summary by CodeRabbit

• New Features

  • Expanded CPU feature detection with clearer “System:” boot messages.
  • Added stderr support for write syscalls.

• Bug Fixes

  • Improved system-call gate setup and interrupt handling for greater stability.
  • Refined AHCI disk I/O timing for more reliable reads/writes.
  • Enhanced FAT directory operations and listing behavior.
  • Adjusted shell behavior: cd no longer changes the current directory.

• Documentation

  • Roadmap phrasing update; structure docs reflect renamed architecture files.

• Chores

  • Build tweaks: added a compiler flag and switched the default CPU model.

[coderabbitai]

Caution

Review failed

The pull request is closed.

Walkthrough

Refactors CPU feature detection into arch/x86_64/features, updates many includes to x64.h, adjusts build flags/sources, modifies syscall write handling and syscall IDT gate setup, adds AHCI read/write APIs and timing tweaks, expands FAT1x directory ops, updates cli/sti barriers, tweaks SwitchToHigherHalf calling convention, simplifies Kernel ACPI messages, and alters shell cd behavior.

Changes

Cohort / File(s)	Summary
CPU feature refactor & includes arch/x86_64/features/x64.c, arch/x86_64/features/x64.h, drivers/APIC.c, drivers/TSC.c, drivers/Vesa.c, kernel/sched/MLFQ.c, kernel/sched/MLFQ.h, mm/MemOps.c, mm/PageFaultHandler.h, mm/trace/StackTrace.h, docs/STRUCTURE.md, meson.build	New CPUFeatureValidation with CPUID; expanded CpuFeatures (sse3/ssse3/sse41/sse42/bmi1/bmi2/fma); replace Cpu.h with x64.h across code; build now uses features path; run CPU model set to max; -mserialize added.
Syscall and IDT updates arch/x86_64/idt/Idt.c, arch/x86_64/syscall/Syscall.c	Syscall gate now uses kernelCodeSegment/flags; SYS_WRITE now handles fd 2 via PrintKernelError; stdout unchanged; others return -1.
AHCI storage enhancements drivers/storage/AHCI.c	Adds AHCI_ReadSectors/AHCI_WriteSectors; wrappers adjust port indexing (i+1 / -1); logs on IO; replaces delay() with delay_us() in waits; integrates new APIs.
FAT1x filesystem changes fs/FAT/FAT1x.c	Adjusted detection returns/logging; adds Fat1xIsDirectory/Fat1xListDirectory; updates directory/file ops and traversal/entry-finding logic.
Low-level barriers include/Io.h	cli()/sti() gain hot/flatten, barriers, and serialize; signatures drop void parameter list.
Switch calling convention include/Switch.h	SwitchToHigherHalf now asmlinkage; adds Kernel.h and stdint.h includes.
Kernel init changes kernel/core/Kernel.c	Removes CPUFeatureValidation block; simplifies ACPI init messages.
Shell behavior kernel/etc/Shell.c	cd no longer updates current directory; only errors on non-directory.
Docs editorial docs/ROADMAP.md	Phrasing change: “Bidirectional filesystem handling.”

Sequence Diagram(s)

sequenceDiagram
  autonumber
  actor User
  participant App as User App
  participant Kernel as Syscall Handler
  participant Out as PrintKernel / PrintKernelError
  User->>App: write(fd, buf, count)
  App->>Kernel: SYS_WRITE(fd, buf, count)
  alt fd == 1 (stdout)
    Kernel->>Out: PrintKernel(buf, count)
    Out-->>Kernel: ok
    Kernel-->>App: return count
  else fd == 2 (stderr)
    Kernel->>Out: PrintKernelError(buf, count)
    Out-->>Kernel: ok
    Kernel-->>App: return count
  else other fd
    Kernel-->>App: return -1
  end

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sequenceDiagram
  autonumber
  participant VFS as BlockDevice Wrapper
  participant AHCI as AHCI_Read/WriteSectors
  participant Port as AHCI Port
  participant DMA as HBA DMA Engine
  VFS->>AHCI: ReadSectors/WriteSectors(port, lba, count, buf)
  AHCI->>Port: Validate init/idle
  AHCI->>Port: AHCI_SendCommand(READ/WRITE_DMA_EX)
  Port->>DMA: Program PRDT / issue FIS
  DMA-->>Port: IRQ/complete
  Port-->>AHCI: status
  AHCI-->>VFS: result

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sequenceDiagram
  autonumber
  participant Boot as CpuInit
  participant CPU as CPUID
  Boot->>CPU: Query features
  CPU-->>Boot: Set sse3/ssse3/sse41/sse42/bmi1/bmi2/fma/...
  alt OSXSAVE not supported
    Boot->>CPU: CPUFeatureValidation()
    CPU-->>Boot: Re-validated flags
  end
  Boot->>CPU: CPUFeatureValidation() (final)
  CPU-->>Boot: Confirmed feature state

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Estimated code review effort

🎯 4 (Complex) | ⏱️ ~60 minutes

Possibly related PRs

• Development #116 — Introduces AHCI driver APIs overlapping with new AHCI_ReadSectors/AHCI_WriteSectors.
• Development #5 — Alters syscall IDT gate setup similar to this PR’s Idt.c change.
• Development #44 — Adjusts CPU feature detection flow related to this refactor into x64.c/x64.h.

Poem

A rabbit taps the kernel’s keys,
Flips CPUIDs on autumn breeze.
AHCI carts the sectors through,
While stderr gets its crimson hue.
Directories hop, yet cd stays still—
Tiny fences guard the mill.
Onward, bits! Let’s burrow and build. 🐇💾

✨ Finishing touches

• 📝 Generate Docstrings

🧪 Generate unit tests

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch Development

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📜 Recent review details

Configuration used: CodeRabbit UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between fd1f1a6 and 322511f.

📒 Files selected for processing (21)

• arch/x86_64/features/x64.c (4 hunks)
• arch/x86_64/features/x64.h (1 hunks)
• arch/x86_64/idt/Idt.c (1 hunks)
• arch/x86_64/syscall/Syscall.c (1 hunks)
• docs/ROADMAP.md (1 hunks)
• docs/STRUCTURE.md (1 hunks)
• drivers/APIC.c (1 hunks)
• drivers/TSC.c (1 hunks)
• drivers/Vesa.c (1 hunks)
• drivers/storage/AHCI.c (8 hunks)
• fs/FAT/FAT1x.c (1 hunks)
• include/Io.h (1 hunks)
• include/Switch.h (1 hunks)
• kernel/core/Kernel.c (1 hunks)
• kernel/etc/Shell.c (1 hunks)
• kernel/sched/MLFQ.c (1 hunks)
• kernel/sched/MLFQ.h (1 hunks)
• meson.build (5 hunks)
• mm/MemOps.c (1 hunks)
• mm/PageFaultHandler.h (1 hunks)
• mm/trace/StackTrace.h (1 hunks)

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