run: add --quit-after-boot, handle rdinit= vs init= there

run

@@ -130,6 +130,13 @@ Set the memory size of the guest. E.g.: `-m 512M`. We try to keep the default
 at the minimal ammount amount that boots all archs. Anything lower could lead
 some arch to fail to boot.
 Default: %(default)s
+'''
+        )
+        self.add_argument(
+            '--quit-after-boot',
+            default=False,
+            help='''\
+Setup a kernel init parameter that makes the emulator quit immediately after boot.
 '''
         )
         self.add_argument(
@@ -212,6 +219,8 @@ Run QEMU with VNC instead of the default SDL. Connect to it with:
         kernel_cli = 'console_msg_format=syslog nokaslr norandmaps panic=-1 printk.devkmsg=on printk.time=y rw'
         if self.env['kernel_cli'] is not None:
             kernel_cli += ' {}'.format(self.env['kernel_cli'])
+        if self.env['quit_after_boot']:
+            kernel_cli += ' {}'.format(self.env['quit_init'])
         kernel_cli_after_dash = ''
         extra_emulator_args = []
         extra_qemu_args = []
@@ -232,11 +241,7 @@ Run QEMU with VNC instead of the default SDL. Connect to it with:
         else:
             vnc = []
         if self.env['eval'] is not None:
-            if self.env['ramfs']:
-                initarg = 'rdinit'
-            else:
-                initarg = 'init'
-            kernel_cli += ' {}=/eval_base64.sh'.format(initarg)
+            kernel_cli += ' {}=/eval_base64.sh'.format(self.env['initarg'])
             kernel_cli_after_dash += ' lkmc_eval="{}"'.format(self.base64_encode(self.env['eval']))
         if not self.env['graphic']:
             extra_qemu_args.extend(['-nographic', LF])