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

README.adoc

@@ -2700,14 +2700,20 @@ ls -lh "$(./getvar linux_image)"
 
 before and after using initramfs, since the `.cpio` is now glued to the kernel image.
 
-Don't forget that to stop using initramfs, you must rebuild the kernel without `--initramfs`:
+Don't forget that to stop using initramfs, you must rebuild the kernel without `--initramfs` to get rid of the attached CPIO image:
 
 ....
 ./build-linux
 ./run
 ....
 
-Also consider using <<linux-kernel-build-variants>> if you need to switch between initramfs and non initramfs often.
+Alternatively, consider using <<linux-kernel-build-variants>> if you need to switch between initramfs and non initramfs often:
+
+....
+./build-buildroot --initramfs
+./build-linux --initramfs --linux-build-id initramfs
+./run --initramfs --linux-build-id
+....
 
 Setting up initramfs is very easy: our scripts just set `CONFIG_INITRAMFS_SOURCE` to point to the CPIO path.
 

common.py

@@ -482,7 +482,7 @@ Valid emulators: {}
         env['buildroot_images_dir'] = join(env['buildroot_build_dir'], 'images')
         env['buildroot_rootfs_raw_file'] = join(env['buildroot_images_dir'], 'rootfs.ext2')
         env['buildroot_qcow2_file'] = env['buildroot_rootfs_raw_file'] + '.qcow2'
-        env['buildroot_cpio'] = join(self.env['buildroot_images_dir'], 'rootfs.cpio')
+        env['buildroot_cpio'] = join(env['buildroot_images_dir'], 'rootfs.cpio')
         env['staging_dir'] = join(env['out_dir'], 'staging', env['arch'])
         env['buildroot_staging_dir'] = join(env['buildroot_build_dir'], 'staging')
         env['target_dir'] = join(env['buildroot_build_dir'], 'target')
@@ -606,8 +606,12 @@ Valid emulators: {}
             env['userland_quit_cmd'] = '/gem5_exit.sh'
         else:
             env['userland_quit_cmd'] = '/poweroff.out'
-        env['quit_init'] = 'init={}'.format(env['userland_quit_cmd'])
-        self.env['ramfs'] = self.env['initrd'] or self.env['initramfs']
+        env['ramfs'] = env['initrd'] or env['initramfs']
+        if env['ramfs']:
+            env['initarg'] = 'rdinit'
+        else:
+            env['initarg'] = 'init'
+        env['quit_init'] = '{}={}'.format(env['initarg'], env['userland_quit_cmd'])
 
         # Kernel modules.
         env['kernel_modules_build_dir'] = join(env['kernel_modules_build_base_dir'], env['arch'])

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])

test-boot

@@ -48,7 +48,7 @@ See ./test --help for --size.
         self.run = self.import_path_main('run')
         self.common_args = self.get_common_args()
         self.common_args['ctrl_c_host'] = True
-        self.common_args['kernel_cli'] = self.env['quit_init']
+        self.common_args['quit_after_boot'] = True
         if (self.env['emulator'] == 'qemu' or
                 (self.env['emulator'] == 'gem5' and self.env['size'] >= 2)):
             self._bench()

trace-boot

@@ -15,13 +15,13 @@ More information at: https://github.com/cirosantilli/linux-kernel-module-cheat#t
     def timed_main(self):
         args = self.get_common_args()
         run = self.import_path_main('run')
-        self.common_args['kernel_cli'] = self.env['quit_init']
         if self.env['emulator'] == 'gem5':
             args['trace'] = 'Exec,-ExecSymbol,-ExecMicro'
             run.main(**args)
         elif self.env['emulator'] == 'qemu':
             run_args = args.copy()
-            args['trace'] = 'exec_tb'
+            run_args['trace'] = 'exec_tb'
+            run_args['quit_after_boot'] = True
             run.main(**run_args)
             qemu_trace2txt = self.import_path_main('qemu-trace2txt')
             qemu_trace2txt.main(**args)