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37 lines
2.3 KiB
Markdown
37 lines
2.3 KiB
Markdown
<div align="center">
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<h1>Filesystem Architecture</h1>
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<p><em>Virtual File System layer and FAT32 abstraction in BoredOS.</em></p>
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</div>
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---
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BoredOS implements a rudimentary but functional filesystem layer designed to support reading system assets and user applications during runtime.
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## 🗂️ Virtual File System (VFS)
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The Virtual File System acts as an abstraction layer across different underlying storage mechanisms (even if, currently, only one type is fully utilized). System calls targeting files (`SYS_FS`) route through the VFS rather than interacting with the disk directly.
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Key VFS functionalities include:
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- **File Descriptors**: Mapping integer IDs to internal file structures for userland processes.
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- **Standard Operations**: Standardizing `open()`, `read()`, `write()`, `close()`, `seek()`, and directory listings.
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- **Path Parsing**: Resolving absolute and relative paths.
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- **SMP Safety**: All VFS and underlying FAT32 operations are protected by a global **Spinlock**. This ensures that multiple cores can safely read from the filesystem simultaneously without corrupting internal file seek pointers or directory cache states.
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## 💾 FAT32 Implementation
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The primary filesystem logic in `fat32.c` handles both in-memory RAM-based filesystem simulation and physical ATA block devices.
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### 💿 Storage Support
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BoredOS supports two main types of storage for its FAT32 implementation:
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1. **RAMFS (Boot Modules)**: During boot, Limine loads necessary files (such as userland `.elf` binaries, fonts, and wallpapers) into memory as standard boot modules. The FAT32 code parses these loaded memory modules and automatically constructs a synthetic FAT32 directory tree inside RAM (mounted as `A:`).
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2. **ATA Drives**: The kernel includes a basic PIO-based ATA driver that can detect and read/write to physical IDE/PATA hard disks.
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- **GPT is NOT supported**: Currently, only **MBR (Master Boot Record)** partition tables or **raw (partitionless)** disks are supported.
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- **Filesystem**: The partition must be formatted as **FAT32**.
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### 🔍 Auto-detection
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The `Disk Manager` automatically probes primary and secondary IDE channels during initialization. If a valid FAT32 partition is found (either directly at sector 0 or via an MBR partition table), the disk is assigned a drive letter (starting from `B:`) and becomes accessible to the VFS.
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---
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