First, Thank you so much for your help.
There are still so problems confuse me.
1. Machine name definition
What does the machine name stand for? The model of CPU or other things.
Compare the start up message and mechine list, I think it stands for the board name:
CPU: Freescale i.MX6DL rev1.3 at 792MHz
CPU: Industrial temperature grade (-40C to 105C) at 44C
Reset cause: POR
So when building image the machine name does not "imx6duallite" but "imx6qsabresd", right?
2.Qt Multimedia function
I think it should be said the system multimedia function.Because Qt Multimedia function work well on vmware ubuntu 14.04 but on the board.
I have rebuilt step by step with the instruction fsl-yocto-L4.1.15_2.0.0-ga/i.MX_Yocto_Project_User's_Guide.pdf, but it still didn't work.
When I used QMediaPlayer, it would show:
defaultServiceProvider::requestService(): no service found for - "org.qt-project.qt.mediaplayer"
When I used QSoundEffect, it would show:
PulseAudioService: pa_context_connect() failed
So I checked something about that like GStreamer and PulseAudio
W: [pulseaudio] main.c: This program is not intended to be run as root (unless --system is specified).
E: [pulseaudio] module-console-kit.c: GetSessionsForUnixUser() call failed: org.freedesktop.DBus.Error.Spawn.PermissionsInvalid: The permission of the setuid helper is not correct
E: [pulseaudio] module.c: Failed to load module "module-console-kit" (argument: ""): initialization failed.
E: [pulseaudio] main.c: Module load failed.
E: [pulseaudio] main.c: Failed to initialize daemon.
*I don't know how to check the GStreamer but can find GStreamer in root fs.
So what should I do next?