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90 lines
2.4 KiB
Plaintext
90 lines
2.4 KiB
Plaintext
---
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sidebar_label: OS-dev (flat-bin + archive)
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---
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# Pure ASM / boot image (flat-bin + archive)
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Minimal OS-dev style pipeline: assemble raw binaries with NASM, then pack a FAT floppy/image with an optional boot sector.
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## Project layout
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```
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myos/
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dcr.toml
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src/
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boot.asm # boot sector (512 bytes)
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kernel.asm # payload
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```
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For multiple flat artifacts, use a **workspace** (one member per binary) or separate packages; a single `flat-bin` package produces one binary per source stem.
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## Boot package (`flat-bin`)
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```toml
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[package]
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name = "boot"
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version = "0.1.0"
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[build]
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language = "asm"
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compiler = "nasm"
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kind = "flat-bin"
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extension = "bin"
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roots = ["src/boot.asm"]
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```
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```bash
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dcr build
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# → target/<…>/debug/boot.bin (NASM -f bin, no link)
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```
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## Disk image after build
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```toml
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[archive]
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output = "target/{profile}/disk.img"
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format = "fat12"
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size = "1440K"
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label = "MYOS"
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bootsector = "target/{profile}/boot.bin"
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[[archive.layout]]
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from = "target/{profile}/kernel.bin"
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to = "KERNEL.BIN"
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```
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* `format`: `fat12`, `fat16`, or `fat32`
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* `size`: bytes or `K`/`KB`/`M`/`MB`/`G`/`GB` (default ~1.44 MiB)
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* `bootsector`: written only when `offset` is omitted or `0`
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* `from` may be a glob; `{profile}` is substituted in paths
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## C kernel → flat binary
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```toml
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[build]
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language = "c"
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compiler = "clang"
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kind = "flat-bin"
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freestanding = true
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filename = "kernel"
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extension = "bin"
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ldflags = ["-T", "linker.ld"]
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```
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Pipeline: objects → temporary linked ELF → `objcopy -O binary` → `kernel.bin`. Requires `objcopy` / `llvm-objcopy` in PATH.
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## Other assemblers
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| Tool | Notes |
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| -------- | --------------------------------------------------------------------------------------- |
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| **FASM** | Write `format binary` in the source; DCR writes `\<stem>.bin` directly |
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| **GAS** | Assemble `.s` → obj → `objcopy -O binary` |
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| **LLC** | `language = "llvm_ir"` → obj → objcopy |
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| **MASM** | COFF obj → objcopy (needs binutils/LLVM objcopy) |
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## Notes
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* Single-file `roots` are supported: `roots = ["src/boot.asm"]`.
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* `--force` re-runs `build.steps` / `build.post_steps` as well as recompilation.
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* Prefer `kind = "elf"` if you need a relocatable ELF kernel without stripping to raw binary.
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