lcd4linux-users

[lcd4linux] Scrolling Display

[Gary P. <gpo...@ra...>]

Hi All,

I have my LCD up and running - using a 16x2 display it is great but I 
want to scroll through different screens to show various information, 
interface throughput, uptime, host name etc

has anyone written a script to do this ?

I have tried to write a script that starts lcd4linux with an external 
file, after a set time it stops lcd4linux and restarts it with the next 
.conf file.

this seemed to be working but now I am getting "LCD4Linux[27637]: fatal 
error: semget() failed: No space left on device" messages
in my syslog file. The LCD freezes on one screen and I need to reboot to 
restart it.

any ideas or suggestions on how to get around this.

Thanks

-- 
Gary 

Re: [lcd4linux] Scrolling Display

[Michael R. <re...@eu...>]

Hi Gary,

> I have tried to write a script that starts lcd4linux with an external
>  file, after a set time it stops lcd4linux and restarts it with the
> next .conf file.
> 
> this seemed to be working but now I am getting "LCD4Linux[27637]:
> fatal error: semget() failed: No space left on device" messages in my
> syslog file. The LCD freezes on one screen and I need to reboot to 
> restart it.

Do you get this error immediately, or from time to time only?

>From the semget() manpage:

> ENOSPC     A  semaphore  set has to be created but the system limit
> for the maximum number of semaphore sets (SEMMNI), or the system wide
> maximum number of semaphores (SEMMNS), would be exceeded.

SEMMNI and SEMMNS can be retrieved from /proc/sys/kernel/sem

LCD4Linux uses semaphores with threads only. Are you using threads
excessively?

Maybe your error comes from a old bug where lcd4linux did not terminate
child processes on exit. Did you try a vurrent SVN version?


HTH, Michael

-- 
Michael Reinelt <re...@eu...>
http://home.pages.at/reinelt
GPG-Key 0xDF13BA50
ICQ #288386781

Re: [lcd4linux] Scrolling Display

[Michael R. <re...@eu...>]

Hi Gray,

please keep your replies on the list! Thanks!

> thanks for the reply, I am running this on Bering - UCLIBC so am not
> sure what version it is.

just run 'lcd4linux -h', it should emit a version number

> I am not sure I understand your question regarding threads ?

Several plugins (namely the exec() plugin) start a separate thread, this
thread communicates with the main process with shared memory and semaphores.

> it seems to run fine for a while and then continuously give the 
> error.

ok. could you please check if you get more and more lcd4linux processes,
until it dies? I suppose it does so. Every process uses one or more
semaphores, until you run out of them.


bye, Michael

-- 
Michael Reinelt <re...@eu...>
http://home.pages.at/reinelt
GPG-Key 0xDF13BA50
ICQ #288386781