Cross-architecture test suite

docs/README.md

@@ -33,6 +33,9 @@ Cutting across all of these:
 - **[arch.md](arch.md) — the architecture split.** How CPU-specific code is kept
   behind a build-time `arch` module so the generic kernel never names x86_64,
   leaving room for other systems (e.g. an AArch64 Raspberry Pi) later.
+- **[testing.md](testing.md) — testing.** How the kernel is tested by booting it in
+  QEMU and asserting on its serial output — reproducibly, and structured so the
+  same tests run across architectures.
 
 ## How the pieces relate
 
@@ -54,6 +57,8 @@ finished, or panics, it **halts** ([halting.md](halting.md)).
 | Kernel entry, panic, bring-up | `src/main.zig` |
 | Shared loader↔kernel contract (`BootInfo`, `Framebuffer`, `MemoryMap`, ABI) | `src/root.zig` |
 | Physical frame allocator | `src/pmm.zig` |
-| Framebuffer text console | `src/console.zig` |
-| Arch-specific kernel code (`halt`, GDT/IDT/TSS, exception stubs, page tables, linker script) | `src/arch/x86_64/` |
+| Framebuffer text console (mirrors to serial) | `src/console.zig` |
+| In-kernel test cases | `src/tests.zig` |
+| Arch-specific kernel code (`halt`, GDT/IDT/TSS, exception stubs, page tables, serial, linker script) | `src/arch/x86_64/` |
 | Build + `run-efi` (QEMU/OVMF) | `build.zig` |
+| QEMU integration test harness | `test/qemu_test.py` |