Linux Software Features

Console

How to enable framebuffer console

The following operations are performed with RSB-4410(4410LBV2080)

linux kernel config

Device Drivers ---> Graphics support ---> <*> Framebuffer Console support

u-boot

setenv bootargs_base 'setenv bootargs console=ttymxc0,115200 console=tty0 enable_wait_mode=off video_mode=extension

files need to be updated

/etc/inittab

tty0::respawn:-/bin/bash

Notice:

If the kernel config is set to "<M> Framebuffer Console support", console will show up after module ,fbcon, is loaded.

How to change debug console port

The following operations demonstrate how to change UBC-DS31's(based on DS31LBV1150) debug console from UART1(ttymxc0) to UART2(ttymxc1).

u-boot

include/configs/mx6q_ubc-d31_recovery.h

#define CONFIG_UART_BASE_ADDR   UART2_BASE_ADDR

include/configs/mx6q_ubc-d31_1G_recovery.h

modify the settings of bootargs_base contained in the pre-defined macro #define CONFIG_EXTRA_ENV_SETTINGS

console=ttymxc1,115200

board/freescale/mx6q_ubc-d31/mx6q_ubc-d31.c

insert the following two lines into static void setup_uart(void)

mxc_iomux_v3_setup_pad(MX6Q_PAD_EIM_D27__UART2_TXD);
mxc_iomux_v3_setup_pad(MX6Q_PAD_EIM_D27__UART2_RXD);

linux kernel

arch/arm/mach-mx6/board-mx6q_advantech.c

modify the following two lines in static void __init mx6_sabresd_timer_init(void)

uart_clk = clk_get_sys("imx-uart.1", NULL);
early_console_setup(UART2_BASE_ADDR, uart_clk);

How to disable debug console

The following operations demonstrate how to disable UBC-DS31's(based on DS31LBV1150) debug console.

u-boot

board/freescale/mx6q_ubc-d31/mx6q_ubc-d31.c

comment out all the code within static void setup_uart(void)

common/console.c

modify the following line in int console_init_f(void)

gd->have_console = 0;

u-boot environment variable

setenv silent=y

change console setting, console=none, within bootargs_base

linux kernel config

Device Drivers ---> Character devices ---> Serial drivers ---> [*] IMX serial port support [ ] Support 4 IMX serial ports [ ] Console on IMX serial port

linux kernel (recommended)

arch/arm/boot/compressed/misc.c

comment out the following lines in void decompress_kernel (...

//putstr("Uncompressing Linux...");

/*
if (ret)
        error("decompressor returned an error");
else
        putstr(" done, booting the kernel.\n");
*/

target root file system

comment out the following line in /etc/inittab

#::respawn:/etc/rc.d/rc_mxc.S

Device Tree

Customize device tree

GStreamer

Play Video

Audio Information

When the system is turned on, you can see the following audio information:

...
ALSA device list:
 #0: imx-audio-sgtl5000
 #1: imx-hdmi-soc
...

Frame Buffer Information

After the system is turned on, you can type command to see frame buffer information. For example:

1. Type command "ls /dev/video", you will see all frame buffer devices ID:

$ video16  video17  video18  video19  video20

2. Type command "cat /sys/class/graphics/fb0/fsl_disp_dev_property", you will see frame buffer name:

$ hdmi

3. The device ID of "hdmi" frame buffer layer is "video16".

4. Type command "cat /sys/class/graphics/fb1/fsl_disp_dev_property", you will see frame buffer name:

$ overlay

5. The device ID of "hdmi" overlay layer is "video17".

6. Type command "cat /sys/class/graphics/fb2/fsl_disp_dev_property", you will see frame buffer name:

$ lcd

7. The device ID of "lcd" frame buffer layer is "video18".

8. Type command "cat /sys/class/graphics/fb3/fsl_disp_dev_property", you will see frame buffer name:

$ overlay

9. The device ID of "lcd" overlay layer is "video19".

10. Type command "cat /sys/class/graphics/fb4/fsl_disp_dev_property", you will see frame buffer name:

$ ldb

11. The device ID of "ldb" frame buffer layer is "video20".

Play Video Command

The format of display video command:

$ GST_COMMAND uri=file://VIDEO_PATH video-sink="VIDEO_COMMAND device=DISPLAY_ID" audio-sink="alsasink device=plughw:AUDIO_ID"

Play Video Command On Yocto 1.5

1. For example:

GST_COMMAND = "gst-launch playbin2"
VIDEO_PATH = "/tools/Advantech.avi"
VIDEO_COMMAND = "mfw_v4lsink"
DISPLAY_ID = "/dev/video17"(hdmi overlay layer)
AUDIO_ID = "0"(audio-sgtl5000) or "1"(audio-hdmi)
AUDIO = ""(Audio) or "volume=0"(No audio)

2. Play video with audio from sgtl5000 audio command:

$ gst-launch playbin2 uri=file:///tools/Advantech.avi video-sink="mfw_v4lsink device=/dev/video17" audio-sink="alsasink device=plughw:0"

3. Play video with audio from HDMI audio command:

$ gst-launch playbin2 uri=file:///tools/Advantech.avi video-sink="mfw_v4lsink device=/dev/video17" audio-sink="alsasink device=plughw:1"

4. Play video with no audio command:

$ gst-launch playbin2 uri=file:///tools/Advantech.avi video-sink="mfw_v4lsink device=/dev/video17" \
  audio-sink="alsasink device=plughw:0" volume=0
or
$ gst-launch playbin2 uri=file:///tools/Advantech.avi video-sink="mfw_v4lsink device=/dev/video17" \
   audio-sink="alsasink device=plughw:1" volume=0

Play Video Command On Yocto 1.7

1. For example:

GST_COMMAND = "gst-launch playbin2" or "gst-launch-0.10 playbin2" or "gst-launch-1.0 playbin"
VIDEO_PATH = "/tools/Advantech.avi"
VIDEO_COMMAND = "imxv4l2sink"
DISPLAY_ID = "/dev/video17"(hdmi overlay layer)
AUDIO_ID = "0"(audio-sgtl5000) or "1"(audio-hdmi)
AUDIO = ""(Audio) or "volume=0"(No audio)

2. Play video with audio from SGTL5000 audio command:

$ gst-launch playbin2 uri=file:///tools/Advantech.avi video-sink="imxv4l2sink device=/dev/video17" audio-sink="alsasink  device=plughw:0"
or
$ gst-launch-0.10 playbin2 uri=file:///tools/Advantech.avi video-sink="imxv4l2sink device=/dev/video17" audio-sink="alsasink  device=plughw:0"
or
$ gst-launch-1.0 playbin uri=file:///tools/Advantech.avi video-sink="imxv4l2sink device=/dev/video17" audio-sink="alsasink  device=plughw:0"

3. Play video with audio from HDMI audio command:

$ gst-launch playbin2 uri=file:///tools/Advantech.avi video-sink="imxv4l2sink device=/dev/video17" audio-sink="alsasink device=plughw:1"
or
$ gst-launch-0.10 playbin2 uri=file:///tools/Advantech.avi video-sink="imxv4l2sink device=/dev/video17" audio-sink="alsasink device=plughw:1"
or
$ gst-launch-1.0 playbin uri=file:///tools/Advantech.avi video-sink="imxv4l2sink device=/dev/video17" audio-sink="alsasink device=plughw:1"

4. Play video with no audio command:

$ gst-launch playbin2 uri=file:///tools/Advantech.avi video-sink="imxv4l2sink device=/dev/video17" \
  audio-sink="alsasink device=plughw:0" volume=0
or
$ gst-launch-1.0 playbin uri=file://tools/Advantech.avi video-sink="imxv4l2sink device=/dev/video17" \
  audio-sink="alsasink device=plughw:0" volume=0

Play Video Command On Yocto 1.8

1. For example:

GST_COMMAND = "gst-launch-1.0 playbin"
VIDEO_PATH = "/tools/Advantech.avi"
VIDEO_COMMAND = "imxv4l2sink"
DISPLAY_ID = "/dev/video17"(hdmi overlay layer)
AUDIO_ID = "0"(audio-sgtl5000) or "1"(audio-hdmi)
AUDIO = ""(Audio) or "volume=0"(No audio)

2. Play video with audio from SGTL5000 audio command:

$ gst-launch-1.0 playbin uri=file:///tools/Advantech.avi video-sink="imxv4l2sink device=/dev/video17" audio-sink="alsasink device=plughw:0"

3. Play video with audio from HDMI audio command:

$ gst-launch-1.0 playbin uri=file:///tools/Advantech.avi video-sink="imxv4l2sink device=/dev/video17" audio-sink="alsasink device=plughw:1"

4. Play video with no audio command:

$ gst-launch-1.0 playbin uri=file://tools/Advantech.avi video-sink="imxv4l2sink device=/dev/video17" \
  audio-sink="alsasink device=plughw:0" volume=0
or
$ gst-launch-1.0 playbin uri=file://tools/Advantech.avi video-sink="imxv4l2sink device=/dev/video17" \
  audio-sink="alsasink device=plughw:1" volume=0

SMPTE color bar

gst-launch videotestsrc ! autovideosink

video rotation

gst-launch filesrc location=/tools/Advantech.avi typefind=true ! aiurdemux name=demux demux. ! \
queue max-size-buffers=0 max-size-time=0 ! vpudec ! mfw_v4lsink rotate=180 demux. ! \
queue max-size-buffers=0 max-size-time=0 ! beepdec ! autoaudiosink

(valid rotate value: 0, 90, 180 or 270)

(While the angle of rotation is 90° or 270°, the maximum video resolution can not be larget than 1024*1024.)

or

gst-launch playbin2 uri=file:///tools/Advantech.avi video-sink="mfw_isink rotation=0"

(valid rotation value: 0~7)

webcam

realtime video

gst-launch v4l2src ! video/x-raw-yuv,width=640,height=480,framerate=20/1 ! autovideosink

take one snapshot

gst-launch v4l2src num-buffers=1 ! jpegenc ! filesink location=sample.jpeg

show one snapshot

VSALPHA=1 gst-launch filesrc location=sample.jpeg ! jpegdec ! imagefreeze ! mfw_isink

network streaming

RTSP(unicast)

sender (ip: 192.168.203.41)

vlc -I rc H.264.mp4 --screen-fps=10 :screen-caching=100 --sout='#rtp{sdp=rtsp://8554/}' -vvv

receiver

gst-launch rtspsrc location=rtsp://192.168.203.41:8554 \
latency=200 name=r  r. ! application/x-rtp,media=video ! \
queue max-size-buffers=0 max-size-time=0 ! rtph264depay ! \
vpudec ! mfw_v4lsink sync=false async=false r. ! \
'application/x-rtp, media=(string)audio' ! queue max-size-buffers=0 max-size-time=0 ! \
rtpmp4gdepay ! beepdec ! alsasink sync=false async=false -vvv

RTP(multicast)

sender

vlc -I rc H.264.mp4 --screen-fps=10 :screen-caching=100 --sout='#rtp{mux=ts,dst=239.1.1.1,port=5004}' -vvv

receiver

route add -net 224.0.0.0 netmask 240.0.0.0 dev eth0 
gst-launch  udpsrc uri=udp://239.1.1.1:5004 \
caps="application/x-rtp,media=(string)video,clock-rate=(int)90000,encoding-name=(string)H264"\
! .recv_rtp_sink_0 gstrtpbin ! queue max-size-buffers=0 max-size-time=0 ! \
rtpmp2tdepay ! mpegtsdemux name=tsdem tsdem. ! queue max-size-buffers=0 max-size-time=0 ! \
vpudec ! mfw_isink sync=false tsdem. tsdem. ! queue max-size-buffers=0 max-size-time=0 ! \
beepdec  ! alsasink sync=false -vvv

Java

How to install Java

Linux Kernel

Get kernel configs from running OS

You can get the .config file in running Linux OS by the following command.

# zcat /proc/config.gz > current.config

Furthermore, this feature is enabled by CONFIG_IKCONFIG_PROC.

Debug kernel panic and oops

To enable kernel symbols & debug information, you have to turn on these options and re-build kernel image. Just remember to keep the vmlinux & System.map files for debugging. They should be located at kernel root folder.

CONFIG_DEBUG_KERNEL=y
CONFIG_KALLSYMS=y
CONFIG_DEBUG_INFO=y
# CONFIG_DEBUG_INFO_REDUCED is not set

Here is an example of Oops case.

Unable to handle kernel NULL pointer dereference at virtual address 00000000
pgd = d8e3c000
[00000000] *pgd=68d76831, *pte=00000000, *ppte=00000000
Internal error: Oops: 17 [#1] PREEMPT SMP ARM
Modules linked in:
CPU: 1 PID: 1030 Comm: pulseaudio Not tainted 3.14.52-svn2009 #3
task: d8f90000 ti: d8b6c000 task.ti: d8b6c000
PC is at dac_get_volsw+0x60/0x74
LR is at dac_get_volsw+0x5c/0x74
pc : [<80558e68>]    lr : [<80558e64>]    psr: 60070013
sp : d8b6dea8  ip : 00000000  fp : d8617400
r10: 7ef214f8  r9 : d8b6c000  r8 : d866e280
r7 : d861757c  r6 : d8617600  r5 : d8948800  r4 : 00000000
r3 : 00000000  r2 : 00000000  r1 : 00000001  r0 : 0000e564
Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment user
Control: 10c53c7d  Table: 68e3c04a  DAC: 00000015
Process pulseaudio (pid: 1030, stack limit = 0xd8b6c238)
Stack: (0xd8b6dea8 to 0xd8b6e000)
dea0:                   80558e08 00000001 d8948800 80535bf4 f01ad000 d861757c
dec0: 00000000 00000009 00000009 00000009 0035f648 00000000 00000000 00000000
dee0: 00000000 00000000 00000000 80967f28 00000007 8001a3c4 6df18338 d8b6dfb0
df00: 00000003 0035f960 7ef21aa4 d80cb410 7ef214f8 d87d53c0 c2c85512 0000000d
df20: d8b6c000 00000000 7ef217f4 800e7f4c d87d53c8 800ebfc0 6ddcf000 800d2e14
df40: 80962860 0000000d 0035ccf8 8069fa10 0000000d 800f19e4 d87d53c0 d87d53c0
df60: 7ef21d94 8069fc88 00000802 d87d53c0 7ef214f8 d87d53c0 c2c85512 0000000d
df80: d8b6c000 00000000 7ef217f4 800e8140 00361b58 00361cbc 00000000 00000036
dfa0: 8000e5e4 8000e460 00361b58 00361cbc 0000000d c2c85512 7ef214f8 0035cdd8
dfc0: 00361b58 00361cbc 00000000 00000036 00361ab0 00361b68 00000007 7ef217f4
dfe0: 6dfa73ac 7ef214ec 6df0efa4 76a5ecbc 20070010 0000000d 00000000 00000000
[<80558e68>] (dac_get_volsw) from [<80535bf4>] (snd_ctl_ioctl+0x5dc/0xb18)
[<80535bf4>] (snd_ctl_ioctl) from [<800e7f4c>] (do_vfs_ioctl+0x3dc/0x59c)
[<800e7f4c>] (do_vfs_ioctl) from [<800e8140>] (SyS_ioctl+0x34/0x5c)
[<800e8140>] (SyS_ioctl) from [<8000e460>] (ret_fast_syscall+0x0/0x38)
Code: e26330fc e585304c eb0501a0 e30e0564 (e5941000)
---[ end trace 7c4f0a24c41cc488 ]---

1. Check the PC (Program Counter) to find out where crash occurs.

PC is at dac_get_volsw+0x60/0x74

2. Grep dac_get_volsw() in System.map and get the symbol name address

$ cd <kernel root folder>
$ grep dac_get_volsw System.map
80558e08 t dac_get_volsw

Note: You can find the program counter is equaled to the sum of function entry address & offset.

pc : [<80558e68>] = 80558e08 + 0x60

3. Run addr2line to read the exact line number in source code.

$ arm-linux-gnueabi-addr2line -f -e vmlinux 80558e68
dac_get_volsw
/home/root/Projects/Linux/fsl-yocto-3.14.52_1.1.0/linux-imx/sound/soc/codecs/sgtl5000.c:335

4-1. In alternative way, you can run objdump to get the disassembly and source code mapping.

$ arm-linux-gnueabi-objdump -DS vmlinux > kernel.objdump

Note: This step may take very long time to generate the dump file. So, maybe you can stop it, once you can find the function symbols in the file.

4-2. Find dac_get_volsw() in kernel.objdump, and check the pc address [<80558e68>]. Then, you can find the problem occurs at the same line of source code.

80558e08 <dac_get_volsw>:
 *                      ------------------------------
 * userspace value      0xc0                         0
 */
static int dac_get_volsw(struct snd_kcontrol *kcontrol,
                         struct snd_ctl_elem_value *ucontrol)
{
80558e08:       e92d4038        push    {r3, r4, r5, lr}
80558e0c:       e1a05001        mov     r5, r1
 ...
        //TEST
        printk("crash test!\n");
80558e60:       eb0501a0        bl      806994e8 <printk>
        printk("%d\n", *p);
80558e64:       e30e0564        movw    r0, #58724      ; 0xe564
80558e68:       e5941000        ldr     r1, [r4]
80558e6c:       e3480080        movt    r0, #32896      ; 0x8080
80558e70:       eb05019c        bl      806994e8 <printk>

NFS

The following operations demonstrate how to boot-up RSB-4410(4410LBV3480) with mounting the root filesystem via NFS.

prerequisites for host
- Network
  e.g. ip address : 172.22.15.145
- NFS service
- NFS root
  e.g. /NFS/rsb-4410_rootfs
  - make one copy of RSB-4410's rootfs located in the directory, /NFS/rsb-4410_rootfs
  - copy the two files, uImage and imx6q-rsb4410.dtb, to /NFS/rsb-4410_rootfs
  - add the following line to /etc/exports
  /NFS *(rw,sync,wdelay,hide,nocrossmnt,insecure,no_root_squash,no_all_squash,subtree_check,secure_locks,acl,anonuid=65534,anongid=65534)
  - execute the following command to export the directory
  $ sudo exportfs -a
u-boot

> setenv serverip 172.22.15.145
> setenv nfsroot /NFS/rsb-4410_rootfs
> run netargs; setenv autoload n; dhcp
> nfs ${loadaddr} /NFS/rsb-4410_rootfs/${uimage}
> nfs ${fdt_addr} /NFS/rsb-4410_rootfs/${fdt_file}
> bootm ${loadaddr} - ${fdt_addr}

screenshot

OpenCV

Open source computer vision

Python

Install Python

SSH

SSH connection

Yocto

In this section, we share some tips to use & modify BB files and related configurations for Yocto.

How to delete temporary workspace after build process

By default, the build system preserves the temporary files under the ${TMPDIR}/work directory of each recipe for inspection and possible debugging purposes. If you would rather have these files deleted to save disk space as the build progresses, you can enable rm_work by adding the following to your local.conf file, which is found in the Build Directory.

INHERIT += "rm_work"

To exclude some recipes from having their work directories deleted by rm_work, you can add the names of the recipe or recipes you are working on to the RM_WORK_EXCLUDE variable, which can also be set in your local.conf file. Here is an example:

RM_WORK_EXCLUDE += "busybox glibc"

How to get multi-sources from GIT server

You can assign a name to distinguish the different GIT URIs, and define different destsuffix to save them respectively. Furthermore, to override SRCREV with the name, you can assign different commit id for each GIT branch.

SRC_URI = " \
    git://git.allseenalliance.org/gerrit/core/alljoyn.git;protocol=https;branch=${GIT_BRANCH};name=router;destsuffix=git/core/alljoyn \     
    git://git.allseenalliance.org/gerrit/services/base.git;protocol=https;branch=${GIT_BRANCH};name=services;destsuffix=git/services/base \
    file://modify_flags_for_yocto.patch"
SRCREV_router = "0d71b216bb3a3cadc615c3eda6f8200093c5e117"
SRCREV_services = "403cda579242701d42d2d7c0da308d63a8f46070"

Skip QA check

You can skip the specific QA check for your packages. For details, check the insane.bbclass bbclass in Yocto Project Reference Manual.

INSANE_SKIP_${PN} += "dev-so"

Create BB file to install pre-built SO binaries

Below is an example to add SO binaries into your image. You may need to modify the blue items for your make install path & library name.

SRC_URI = "file://test.tar.gz"

S = "${WORKDIR}/test"

do_install() {
    install -d ${D}/usr/lib
    cp -axr ${S}/lib*.* ${D}/usr/lib/
}

# Avoid package splitting into run-time and debug components
 INHIBIT_PACKAGE_DEBUG_SPLIT = "1"
# Avoid QA Error for already-stripped
 INHIBIT_PACKAGE_STRIP = "1"
# List the files for Package
 FILES_${PN} += "/usr/lib"
# Put all SO files in main rpm package
 FILES_SOLIBSDEV = ""
 INSANE_SKIP_${PN} += "dev-so"
# Set alias name to satisfy runtime dependencies
 RPROVIDES_${PN} = "libtest-1.00.so"

Install Node-RED packages

For Node-RED package installation, you can refer to the example below. Please note this example is based on the imyller's meta-nodejs layer for Node.js infrastructure.

SRC_URI =  "git://github.com/ADVANTECH-Corp/node-red-contrib-alljoyn.git;protocol=git"
SRCREV = "677333b1ed1a26a966c32d98af073d0b9a2b9088"

S = "${WORKDIR}/git"

# Inherit NPM class
inherit npm-install-global

# Do node-gyp rebuild in do_install() phase
NPM_INSTALL_FLAGS = "--unsafe-perm"

# Skip QA check
INSANE_SKIP_${PN} = "staticdev"

How to add additional gst-plugins

add new settings in Yocto's conf/local.conf

LICENSE_FLAGS_WHITELIST = "commercial"

COMMERCIAL_AUDIO_PLUGINS ?= " \
gst-plugins-ugly-mad \
gst-plugins-ugly-mpegaudioparse \
"
COMMERCIAL_VIDEO_PLUGINS ?= " \
gst-plugins-ugly-mpeg2dec \
gst-plugins-ugly-mpegstream \
gst-plugins-bad-mpegvideoparse \
"
CORE_IMAGE_EXTRA_INSTALL += " \
gst-plugins-bad-mpegtsdemux \
gst-plugins-bad-fbdevsink \
gst-ffmpeg \
"

overwrite original hash code specified in the recipe x264_git

cat << EOF > meta-advantech/recipes-multimedia/x264/x264_git.bbappend
SRCREV = "ffc3ad4945da69f3caa2b40e4eed715a9a8d9526"
EOF

snapshot verified

How to use Yocto Project Application Development Toolkit (ADT)

(see Setting-up Eclipse Plug-in to cross compile for iMX6 series)

How to add & use Chromium browser

add new settings in conf/local.conf

LICENSE_FLAGS_WHITELIST = "commercial"
CORE_IMAGE_EXTRA_INSTALL += "chromium"

switch "OpenGL ES H/W acceleration" on

edit /usr/share/applications/google-chrome.desktop

[Desktop Entry]
...
Exec=/usr/bin/google-chrome --use-gl=egl %U
...

HTML5 scores

Linux Software Features

Contents

Console

How to enable framebuffer console

How to change debug console port

How to disable debug console

Device Tree

GStreamer

Play Video

Audio Information

Frame Buffer Information

Play Video Command

Play Video Command On Yocto 1.5

Play Video Command On Yocto 1.7

Play Video Command On Yocto 1.8

SMPTE color bar

video rotation

webcam

realtime video

take one snapshot

show one snapshot

network streaming

RTSP(unicast)

RTP(multicast)

Java

Linux Kernel

Get kernel configs from running OS

Debug kernel panic and oops

NFS

OpenCV

Python

SSH

Yocto

How to delete temporary workspace after build process

How to get multi-sources from GIT server

Skip QA check

Create BB file to install pre-built SO binaries

Install Node-RED packages

How to add additional gst-plugins

How to use Yocto Project Application Development Toolkit (ADT)

How to add & use Chromium browser

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