Stage 8

docs/stage8.md

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+# CLeonOS Stage8
+
+## Stage Goal
+- Add kernel driver abstraction and registration framework.
+- Register built-in drivers (serial, framebuffer, tty) under a unified manager.
+- Probe `/driver` directory ELF drivers from ramdisk and validate ELF metadata.
+- Extend user app packaging to include driver ELF in `/driver`.
+
+## Acceptance Criteria
+- Kernel boots and prints `CLEONOS STAGE8 START`.
+- Driver framework logs `DRIVER MANAGER ONLINE`.
+- Built-in drivers are registered and total driver count is logged.
+- `/driver/*.elf` files are discovered, validated, and logged as `DRIVER ELF READY`.
+- System continues to scheduler/interrupt/syscall idle loop without panic.
+
+## Build Targets
+- `make setup`
+- `make userapps`
+- `make iso`
+- `make run`
+- `make debug`
+
+## QEMU Command
+- `qemu-system-x86_64 -M q35 -m 1024M -cdrom build/CLeonOS-x86_64.iso -serial stdio`
+
+## Common Bugs and Debugging
+- `DRIVER ELF INVALID`:
+  - Verify ELF is built as x86_64 ELF64 and has valid program headers.
+- `DRIVER ELF MISSING`:
+  - Ensure `make userapps` finished and ramdisk staging copied files to `/driver`.
+- Driver count is lower than expected:
+  - Check `clks_driver_init()` call order occurs after `clks_fs_init()`.
+- Build failure for `ttydrv_main.c` symbols:
+  - Confirm `cleonos/c/apps/ttydrv_main.c` exists and `USER_TTYDRV_OBJECT` is in Makefile.
+- No driver logs on boot:
+  - Confirm kernel includes `clks/kernel/driver.c` in `C_SOURCES`.