a few new syscalls, init process

code/init/init.c

@@ -0,0 +1,40 @@
+// init.c - first user-mode process
+#include <stdint.h>
+#include <stdbool.h>
+#include <stddef.h>
+
+// ---------------------------------------------------------------------------
+// Syscall stubs
+// ---------------------------------------------------------------------------
+extern uint32_t SysCreateProcess(const char* path, uint32_t* handleOut,
+                                  const char* cmdline);
+extern uint32_t SysCloseHandle(uint32_t handle);
+extern void     SysDebugPrint(const char* str);
+extern uint32_t SysWaitForProcess(uint32_t handle);
+extern void     SysExitProcess(int code);
+extern void     SysYield(void);
+
+#define STATUS_SUCCESS 0u
+
+void _start()
+{
+    uint32_t h = 0;
+    uint32_t s = 0;
+ 
+    SysDebugPrint("[init] starting shell\n");
+    s = SysCreateProcess("shell.exe", &h, NULL);
+    if (s != STATUS_SUCCESS) {
+        SysDebugPrint("[init] FATAL: failed to start shell.exe\n");
+        SysExitProcess(1);
+    }
+ 
+    SysDebugPrint("[init] waiting for shell\n");
+    s = SysWaitForProcess(h);
+    if (s != STATUS_SUCCESS)
+        SysDebugPrint("[init] WARNING: SysWaitForProcess returned error\n");
+    SysCloseHandle(h);
+
+    SysDebugPrint("[init] done\n");
+
+    SysExitProcess(0);
+}