Simple IPC with pipes

ulib/system/processctl.c

@@ -0,0 +1,8 @@
+#include <stdint.h>
+#include <sysdefs/processctl.h>
+#include <sysdefs/syscall.h>
+#include <syscall/syscall.h>
+
+int32_t processctl(uint64_t pid, uint64_t cmd, void *extra) {
+  return syscall(SYS_PROCESSCTL, pid, cmd, (uint64_t)extra, 0, 0, 0);
+}