cleonos/docs/stage24.md

CLeonOS Stage24

Stage Goal

• Add a kernel shell command panic.
• Trigger a deliberate kernel panic from shell command input.
• Show a dedicated panic screen in framebuffer mode for manual panic and CPU exceptions.

What Was Implemented

• New panic subsystem:
  • clks/include/clks/panic.h
  • clks/kernel/panic.c
• Panic subsystem behavior:
  • disable interrupts before panic halt
  • write panic summary to serial (-serial stdio)
  • draw full-screen panic page on framebuffer
  • halt forever after panic
• Exception path integration:
  • clks/kernel/interrupts.c now routes vector < 32 to clks_panic_exception(...)
• Shell integration:
  • clks/kernel/shell.c adds panic command
  • panic command calls clks_panic("MANUAL PANIC FROM KERNEL SHELL")
  • help output includes panic
• Stage banner updated:
  • CLEONOS Stage24 START

Acceptance Criteria

• Kernel boots and prints CLEONOS Stage24 START.
• help lists panic.
• Typing panic in kernel shell shows panic page and system halts.
• Triggering CPU exceptions (if any) also enters the same panic screen flow.

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

• panic command not found:
  • Confirm help output contains panic and shell dispatch includes clks_shell_cmd_panic().
• Panic screen not visible but serial has panic logs:
  • Ensure framebuffer is available from Limine and clks_fb_ready() is true.
• Exception still prints old logs instead of panic page:
  • Check clks_interrupt_dispatch() exception branch routes to clks_panic_exception(...).