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README.md

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+# elibc — Standard C Library for Elyz
+
+Minimal C library for the Elyz OS, based on musl's organisational principles
+but adapted to Elyz's capability-based, syscall-less architecture.
+
+## Structure
+
+```
+elibc/
+├── arch/               # Architecture-specific code
+│   ├── generic/        # Fallback implementation & abstract interfaces
+│   │   ├── kcall.h          #  Kernel-call abstraction (no syscalls in Elyz)
+│   │   ├── startup_info.h   #  Process-startup description
+│   │   └── bits/            #  Type-size definitions
+│   └── x86_64/         # x86_64 port
+│       ├── kcall.h           #  Kernel-call placeholder (ABI TBD)
+│       ├── startup_info.h    #  x86_64 startup layout (ABI TBD)
+│       ├── atomic_arch.h     #  Locked cmpxchg / atomic ops
+│       └── bits/
+├── include/            # Public headers (POSIX-like API)
+├── src/                # Source implementations
+│   ├── internal/       #  Libc state, errno, bump allocator (temporary)
+│   ├── string/         #  Pure-C string ops (memcpy, strlen, etc.)
+│   ├── stdio/          #  (reserved)
+│   └── stdlib/         #  atoi, etc.
+├── crt/                # C runtime entry point
+├── Makefile
+└── configure
+```
+
+## Key differences from a traditional libc (glibc/musl)
+
+| Traditional (Linux) | Elyz / elibc |
+|---|---|
+| `syscall`/`int 0x80` | Capability invocation → PM Actor messaging |
+| `brk`/`sbrk` | `ELYZ_OP_ALLOCATE` via `elyz_kcall` |
+| `_exit` syscall | `ELYZ_OP_EXIT` via kcall |
+| `errno` via TLS | `__errno_location` (plain global for now) |
+
+## Porting to a new arch
+
+1. Create `arch/<name>/` with:
+   - `kcall.h` — kernel-call mechanism
+   - `startup_info.h` — process-startup layout
+   - `arch.mak` — arch-specific compiler/linker flags
+   - `bits/alltypes.h.in` — type sizes
+   - `atomic_arch.h` — atomic ops (optional, fallback exists)
+2. Add detection in `configure`
+3. Build: `./configure && make`
+
+## Building
+
+```
+./configure
+make
+```