[tips] [Howto] Support Nvidia Optimus on Ubuntu 12.04 LTS (precise) [No Bumblebee needed]

For laptops which use muxless Nvidia Optimus, there's a new way to support officially on Ubuntu 12.04 LTS.

 #sudo apt-get install nvidia-319-updates nvidia-prime xserver-xorg-lts-raring 

The command will upgrade
 * kernel to 3.8 ,
 * X server RandR to 1.4
 * Install Nvidia driver version 319.

After reboot, it will use nvidia driver by default.
There is no need to upgrade to 13.10 if you prefer 12.04 LTS.

[tips] g_clear_pointer

因為在tracking一個bug, 
所以要backport indicator-power這個package到ubuntu precise.
意外發現了glib在2.33之後支援的一個還滿好用的function: 
g_clear_pointer()

簡言之以前的寫法,要把物件刪除再把指標設為NULL:

if (priv->object_path != NULL) {
    g_free(priv->object_path);
    priv->object_path = NULL;
}

現在只要一行就可以達成了

g_clear_pointer (&priv->object_path, g_free);

當然要backport的話作法就是相反~~