Add pattern to ignore middle files in gitignore
kernel code test: register a net dev

This test is trying to investigate how to register a network device into the
system.

Here is the firt step. After doing this, you can see a network device under
/sys/class/net/.

Fantastic, even this device is useless now.
qemu code read: how migrate works

This note start from the monitor command "migrate" and focus on the migration
on tcp connection.
kernel code test: virtual net dev

This is really a workable device~

Can assign IP address and ping it.
qemu code reading: migration

This note start from the monitor command, "migrate" and focus on the migration
on tcp connection.

Well, function migrate_fd_connect() is the core function for migration.