Issues with CUPS

Issues with CUPS

[Alexander Asteroth]

Dear Daniel and Tobias,

I'm having trouble with cups on guix-system as well. I added it to the
system with

> (service  cups-service-type
>           (cups-configuration
>    	(web-interface? #t)
>    	(extensions (list cups-filters hplip-minimal))))

When the system is restarted and I try to access cups via localhost:631,
after clicking on some (admin) link to add a printer (or similar) it
takes 2minutes (exactly) for the page to show up. In
/var/log/cups/access_log and .../error_log numerrous repeated entries

> ==> /var/log/cups/access_log <==
> localhost - root [03/Dec/2021:15:26:11 +0100] "GET /admin/conf/cupsd.conf HTTP/1.1" 200 0 - -
> localhost - - [03/Dec/2021:15:26:11 +0100] "GET /admin/conf/cupsd.conf HTTP/1.1" 401 0 - -
>
> ==> /var/log/cups/error_log <==
> I [03/Dec/2021:15:26:11 +0100] [Client 313] Started "/gnu/store/9vm70ai4914w283sghx3vdz7gqja53j3-cups-server-bin/lib/cups/cgi-bin/admin.cgi" (pid=1341, file=166)

are found.

At some point is says:

> ==> /var/log/cups/access_log <==
> localhost - root [03/Dec/2021:15:26:11 +0100] "GET /admin/conf/cupsd.conf HTTP/1.1" 200 0 - -
>
> ==> /var/log/cups/error_log <==
> W [03/Dec/2021:15:26:11 +0100] Max clients reached, holding new connections...
>
> ==> /var/log/cups/access_log <==
> localhost - - [03/Dec/2021:15:26:11 +0100] "GET /admin/conf/cupsd.conf HTTP/1.1" 401 0 - -
>
> ==> /var/log/cups/error_log <==
> I [03/Dec/2021:15:26:11 +0100] Resuming new connection processing...
> W [03/Dec/2021:15:26:11 +0100] Max clients reached, holding new connections...
> I [03/Dec/2021:15:26:11 +0100] Resuming new connection processing...
> W [03/Dec/2021:15:26:11 +0100] Max clients reached, holding new connections...
> I [03/Dec/2021:15:26:11 +0100] Resuming new connection processing...
> W [03/Dec/2021:15:26:11 +0100] Max clients reached, holding new connections...
> I [03/Dec/2021:15:26:11 +0100] [Client 401] Started "/gnu/store/9vm70ai4914w283sghx3vdz7gqja53j3-cups-server-bin/lib/cups/cgi-bin/admin.cgi" (pid=1363, file=210)
>
> ==> /var/log/cups/access_log <==
> localhost - root [03/Dec/2021:15:26:11 +0100] "GET /admin/conf/cupsd.conf HTTP/1.1" 200 0 - -
>
> ==> /var/log/cups/error_log <==
> I [03/Dec/2021:15:28:11 +0100] Resuming new connection processing...

As you can see, the first messages all happen instantly and after the
max client message there is a 2 min pause.

I have also another problem related to my printer wich is a Samsung
SCX-472x-series (accessed over ethernet). On openprinting.org the
suggested driver is
(https://www.openprinting.org/printer/Samsung/Samsung-SCX-472x) from
Samsung. So far I used it on debian and arch and it worked perfect, but
I thik it's non-GPL.

I can import only the ppd file for my printer but this refers to some
filter
/gnu/store/2q9cn98ahgba3fjgvjlnlvb4j928z17j-cups-server-bin/lib/cups/filter/rastertospl
which is not present in guix (but would be installed by the Samsung
installer to some place noexistent in guix). 

Any idea how to prodeed to get my printing working?

Cheers,

	Alex

Re: Issues with CUPS

[Tobias Geerinckx-Rice]

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Alexander,

Alexander Asteroth 写道：
> When the system is restarted and I try to access cups via 
> localhost:631,
> after clicking on some (admin) link to add a printer (or 
> similar) it
> takes 2minutes (exactly) for the page to show up. In
> /var/log/cups/access_log and .../error_log numerrous repeated 
> entries

This sounds like the bug long fixed on core-updates (‘any day now’ 
:-) that hasn't made it to master yet[0].  A simple

  $ sudo touch /etc/cups/cupsd.conf

to create the file in question should work around it for now.

Maybe remember to delete it post-c-u-merge, or don't; an empty 
file doesn't waste much space.

> I have also another problem related to my printer wich is a 
> Samsung
> SCX-472x-series (accessed over ethernet). On openprinting.org 
> the
> suggested driver is
> (https://www.openprinting.org/printer/Samsung/Samsung-SCX-472x) 
> from
> Samsung. So far I used it on debian and arch and it worked 
> perfect, but
> I thik it's non-GPL.

OpenPrinting claims that it's ‘MIT’ but a brief search didn't lead 
me to anything resembling source code.  Samsung's printer division 
being absorbed by HP doesn't help.

> I can import only the ppd file for my printer but this refers to 
> some
> filter

Yeah, PPD files are just metadata files for actual 
printers/drivers and downloading them separately is usually 
pointless.

> Any idea how to prodeed to get my printing working?

Not really, I'm afraid.  The only Samsung laser printers I've ever 
used with Guix worked fine with SpliX.  It does not provide a 
rastertospl filter, only rastertoqpdl.

The most likely path forward is to find the sources to the 
pxlmono{-Samsung,} package if they exist.

I started packaging the Ghostscript Printer Application this week, 
which we'll need when CUPS removes support for printer drivers 
completely.  I'll check whether it contains anything relevant when 
I get back.  I'm not hopeful.

Kind regards,

T G-R

[0]: https://issues.guix.gnu.org/42068#0

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Re: Issues with CUPS

[Tobias Geerinckx-Rice]

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…all that said: adding a non-exstistent SCX-472x and printing a 
test page to it works fine here!

- Which PPD file did you import?  Was it[0]?  If not, try that.
- Why remove foomatic-filters from the default CUPS extensions 
  list?

Customising the extensions field before knowing which driver 
supports your printer is premature.  I recommend removing it 
before continuing, or at least trying more drivers if the default 
of ‘all’ is not an option here.

Good luck!

T G-R

[0]: 
https://openprinting.org/ppd-o-matic.php?driver=pxlmono&printer=Samsung-SCX-472x&.submit=Generate+PPD+file&show=1&.cgifields=show&.cgifields=shortgui

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Re: Issues with CUPS

[Alexander Asteroth]

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Hi Tobias,

thanks for the hint (see below). After touching /etc/cups/cupsd.conf it
immediately worked perfectly fine.

W.r.t. your other email:

> - Which PPD file did you import?  Was it[0]?  If not, try that.

I have no idea what it[0] is. The ppd I used before is from the Samsung
uld-package and is called Samsung_SCX-472x_Series.ppd

> - Why remove foomatic-filters from the default CUPS extensions   list?

I was not aware that adding filters to the service description overrides
the filters default values. I thought it just add's them and somewhere
it was remommended adding the hplib-minimal filters, and in my
helplessness I tried everything ;-)

Anyway, I gave other Samsung drivers a try and with the SCX-5330N I found a
driver that also seems to work with my SCX-4729.

... Now it works! Thanks!

Cheers,

	Alex


On Fri, Dec 03 2021, 21:25:56, Tobias Geerinckx-Rice <me@tobias.gr> wrote:

> [[PGP Signed Part:Undecided]]
> Alexander,
>
> Alexander Asteroth 写道：
>> When the system is restarted and I try to access cups via
>> localhost:631,
>> after clicking on some (admin) link to add a printer (or similar) it
>> takes 2minutes (exactly) for the page to show up. In
>> /var/log/cups/access_log and .../error_log numerrous repeated
>> entries
>
> This sounds like the bug long fixed on core-updates (‘any day now’ :-)
> that hasn't made it to master yet[0].  A simple
>
>  $ sudo touch /etc/cups/cupsd.conf
>
> to create the file in question should work around it for now.
>
> Maybe remember to delete it post-c-u-merge, or don't; an empty file
> doesn't waste much space.
>
>> I have also another problem related to my printer wich is a Samsung
>> SCX-472x-series (accessed over ethernet). On openprinting.org the
>> suggested driver is
>> (https://www.openprinting.org/printer/Samsung/Samsung-SCX-472x) from
>> Samsung. So far I used it on debian and arch and it worked perfect,
>> but
>> I thik it's non-GPL.
>
> OpenPrinting claims that it's ‘MIT’ but a brief search didn't lead me
> to anything resembling source code.  Samsung's printer division being
> absorbed by HP doesn't help.
>
>> I can import only the ppd file for my printer but this refers to
>> some
>> filter
>
> Yeah, PPD files are just metadata files for actual printers/drivers
> and downloading them separately is usually pointless.
>
>> Any idea how to prodeed to get my printing working?
>
> Not really, I'm afraid.  The only Samsung laser printers I've ever
> used with Guix worked fine with SpliX.  It does not provide a 
> rastertospl filter, only rastertoqpdl.
>
> The most likely path forward is to find the sources to the
> pxlmono{-Samsung,} package if they exist.
>
> I started packaging the Ghostscript Printer Application this week,
> which we'll need when CUPS removes support for printer drivers 
> completely.  I'll check whether it contains anything relevant when I
> get back.  I'm not hopeful.
>
> Kind regards,
>
> T G-R
>
> [0]: https://issues.guix.gnu.org/42068#0
>
> [[End of PGP Signed Part]]


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Re: Issues with CUPS

[Tobias Geerinckx-Rice]

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Alexander,

Alexander Asteroth 写道：
>> - Which PPD file did you import?  Was it[0]?  If not, try that.
>
> I have no idea what it[0] is.

This is about to become amusingly confusing, because I'm in turn 
not sure what ‘it[0]’ refers to above.

If you mean the ‘[0]’: there was a link at the bottom of my mail 
to the PPD I tried.

If you mean the file itself: it's what this form[1] (another link 
below :-) produces from selecting your printer model and clicking 
‘Generate PPD file’.

I did not inspect how that site works, but as modern CUPS 
autogenerates .ppd files from .drv files, I expect it to do the 
same.

> The ppd I used before is from the Samsung uld-package

That's the binary-only (and hence unsupportable) .deb, right?

>> - Why remove foomatic-filters from the default CUPS extensions 
>> list?
>
> I was not aware that adding filters to the service description 
> overrides
> the filters default values. I thought it just add's them and 
> somewhere
> it was remommended adding the hplib-minimal filters, and in my
> helplessness I tried everything ;-)

Wait, so it didn't work with the default list?  :-(

Also, was it not clear from the Guix manual that the default list 
should include all viable drivers?  If you have any suggestions to 
improve the wording, please let me know!

> Anyway, I gave other Samsung drivers a try and with the 
> SCX-5330N I found a
> driver that also seems to work with my SCX-4729.

Great!  All's well that ends well.

I find it strange that the foomatic package doesn't offer you 
exact printer model when it probably supports it, but that's not 
really a Guix bug, I think.

Happy printing,

T G-R

[0]: 
https://openprinting.org/ppd-o-matic.php?driver=pxlmono&printer=Samsung-SCX-472x&.submit=Generate+PPD+file&show=1&.cgifields=show&.cgifields=shortgui
[1]: https://www.openprinting.org/driver/pxlmono

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Re: Issues with CUPS

[Daniel Meißner]

Hi Alexander, hi Tobias,

Tobias Geerinckx-Rice writes:
> Alexander Asteroth 写道：
>> When the system is restarted and I try to access cups via
>> localhost:631, after clicking on some (admin) link to add a printer
>> (or similar) it takes 2minutes (exactly) for the page to show up. In
>> /var/log/cups/access_log and .../error_log numerrous repeated entries
>
> This sounds like the bug long fixed on core-updates (‘any day now’ :-)
> that hasn't made it to master yet[0].  A simple
>
>   $ sudo touch /etc/cups/cupsd.conf
>
> to create the file in question should work around it for now.

Thank you very much! I have had the same issues with the web-interface
under http://localhost:631/admin.  After creating the file, it works
perfectly.  I was going to mention this problem in the thread
<https://lists.gnu.org/archive/html/help-guix/2021-12/msg00000.html>
also, since I thought it was related to my problem there.

Best
Daniel