BBBW and X desktop

Stephane_Charette · December 21, 2016, 12:08pm

My BBBW was working correctly when I received it a few days ago. Maybe I should I have stopped there.

Wanting to use the newest build, I downloaded and installed this build: https://rcn-ee.com/rootfs/bb.org/testing/2016-12-18/lxqt-4gb/BBBW-blank-debian-8.6-lxqt-4gb-armhf-2016-12-18-4gb.img.xz

Now it still boots, I can login to the debug serial console and poke around as usual. But I’m no longer getting the graphical LXQT desktop on the micro HDMI. Just a black screen with a flashing text mode cursor in the top left.

Before I dig further, I wanted to confirm I’m using the correct build. Should the build I quoted above resulted in a graphical desktop once installed on a BBBW device?

Stéphane

Stephane_Charette · December 23, 2016, 9:33am

[I’m using] this build: https://rcn-ee.com/rootfs/bb.org/testing/2016-12-18/lxqt-4gb/BBBW-blank-debian-8.6-lxqt-4gb-armhf-2016-12-18-4gb.img.xz

When the BBBW boots up, I see this message on the serial console:

[FAILED] Failed to start Light Display Manager.
See ‘systemctl status lightdm.service’ for details.

If it matters, my hookup is like this: BBBW → micro HDMI → HDMI-to-DVI-adapter → DVI to old DELL flat screen display.

When I run “systemctl status lightdm.service”, part of what I see is this:

Dec 23 00:39:16 beaglebone systemd[1]: lightdm.service: Start request repeated too quickly.
Dec 23 00:39:16 beaglebone systemd[1]: Failed to start Light Display Manager.
Dec 23 00:39:16 beaglebone systemd[1]: lightdm.service: Unit entered failed state.
Dec 23 00:39:16 beaglebone systemd[1]: lightdm.service: Failed with result ‘start-limit-hit’.

If I wait a minute or so and then manually run the command “sudo systemctl start lightdm” then the desktop starts fine.

After poking around, I found a solution. Turns out the default pause between retries for systemd to restart a service is 100ms, and it only retries a maximum of 5 times within 10 seconds before it gives up forever. So I added the following lines to /etc/systemd/system/display-manager.service:

RestartSec=5s

TimeoutSec=60s
StartLimitInterval=5min
StartLimitBurst=60

With this, the X desktop now starts up every time on my BBBW.

Robert, is the file /etc/systemd/system/display-manager.service something that we control, or does it come from an upstream source? Can we easily make modifications to it to increase the length between restarts, and increase the number of times systemd tries to restart it?

Stéphane

RobertCNelson · December 23, 2016, 3:26pm

Nice!!

[I'm using] this build:
https://rcn-ee.com/rootfs/bb.org/testing/2016-12-18/lxqt-4gb/BBBW-blank-debian-8.6-lxqt-4gb-armhf-2016-12-18-4gb.img.xz

When the BBBW boots up, I see this message on the serial console:

[FAILED] Failed to start Light Display Manager.
See 'systemctl status lightdm.service' for details.

If it matters, my hookup is like this: BBBW -> micro HDMI ->
HDMI-to-DVI-adapter -> DVI to old DELL flat screen display.

When I run "systemctl status lightdm.service", part of what I see is this:

Dec 23 00:39:16 beaglebone systemd[1]: lightdm.service: Start request
repeated too quickly.
Dec 23 00:39:16 beaglebone systemd[1]: Failed to start Light Display
Manager.
Dec 23 00:39:16 beaglebone systemd[1]: lightdm.service: Unit entered failed
state.
Dec 23 00:39:16 beaglebone systemd[1]: lightdm.service: Failed with result
'start-limit-hit'.

If I wait a minute or so and then manually run the command "sudo systemctl
start lightdm" then the desktop starts fine.

After poking around, I found a solution. Turns out the default pause
between retries for systemd to restart a service is 100ms, and it only
retries a maximum of 5 times within 10 seconds before it gives up forever.
So I added the following lines to
/etc/systemd/system/display-manager.service:

RestartSec=5s
TimeoutSec=60s
StartLimitInterval=5min
StartLimitBurst=60

With this, the X desktop now starts up every time on my BBBW.

Robert, is the file /etc/systemd/system/display-manager.service something
that we control, or does it come from an upstream source? Can we easily
make modifications to it to increase the length between restarts, and
increase the number of times systemd tries to restart it?

I've been doing a evil hack for lcd's:

github.com

RobertCNelson/boot-scripts/blob/master/boot/am335x_evm.sh#L449-L460


      
          			if [ ! "x${USB_NETWORK_RNDIS_DISABLED}" = "xyes" ]; then
          				mkdir -p functions/rndis.usb0
          				# first byte of address must be even
          				echo ${cpsw_2_mac} > functions/rndis.usb0/host_addr
          				echo ${cpsw_1_mac} > functions/rndis.usb0/dev_addr
          
          				# Starting with kernel 4.14, we can do this to match Microsoft's built-in RNDIS driver.
          				# Earlier kernels require the patch below as a work-around instead:
          				# https://github.com/beagleboard/linux/commit/e94487c59cec8ba32dc1eb83900297858fdc590b
          				if [ -f functions/rndis.usb0/class ]; then
          					echo EF > functions/rndis.usb0/class
          					echo 04 > functions/rndis.usb0/subclass

but i like your setup better..

/etc/systemd/system/display-manager.service is a symlink too:

/lib/systemd/system/lightdm.service

I'll just patch lightdm and push it out:

https://packages.debian.org/jessie/lightdm

Regards,

RobertCNelson · December 23, 2016, 3:55pm

and pushed out to the repo..

That works so much nicer then my race hack!

sudo apt update ; sudo apt upgrade

Regards,