I have used my Acer USB scanner extensively with Kooka under Kubuntu, but suddenly it crashes at startup. Strace shows
read(13, "/dev/scanner\n", 4096) = 13
--- SIGILL (Illegal instruction) @ 0 (0) ---
and indeed there is no /dev/scanner. Of course at this point I don't know whether there ever was one. I tried installing xsane and it crashes with the same error.

So my question: Is the problem really the missing /dev/scanner, and if so how do I make one?
In case this helps, in /proc/bus/usb/devies I find
T: Bus=02 Lev=02 Prnt=02 Port=03 Cnt=02 Dev#= 5 Spd=12 MxCh= 0
D: Ver= 1.00 Cls=ff(vend.) Sub=ff Prot=ff MxPS= 8 #Cfgs= 1
P: Vendor=04a5 ProdID=20b0 Rev= 1.00
S: Manufacturer=Color
S: Product= FlatbedScanner 22
C:* #Ifs= 1 Cfg#= 1 Atr=40 MxPwr=100mA
I: If#= 0 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=ff Driver=(none)
E: Ad=81(I) Atr=02(Bulk) MxPS= 64 Ivl=0ms
E: Ad=02(O) Atr=02(Bulk) MxPS= 8 Ivl=0ms
E: Ad=83(I) Atr=03(Int.) MxPS= 8 Ivl=16ms

Thank you very much for any help.

only to see if it's a kooka problem or something else, try to install & run sane - xsane (on ubuntu is installed by default, but not in kubuntu).
and by the way, i have read that /dev/scanner is used only in old 2.4 kernels, so, i think that's a bit deprecated!

tell me if things go better with xsane!

good bye

Matteo

OK, I did install sane/xsane and it crashes with the same /dev/scanner issue near the end of the crash log.

Any other ideas for what to try? I looked at /dev/makedevs but scanner does not appear in it.

Could it be a hardware recognition problem? I did try out a little USB webcam in between the last good scan and the first kooka crash. And the scanner is USB, of course... But the webcam is disconnected now, and at least one reboot did not bring the scanner back to life.

For the benefit of other struggling scanners:
I got the scanner back to work by uninstalling and re-installing kooka and all sane packages (and kubuntu-desktop which depends on kooka), a total of 7 packages.

First I thought the Kubuntu hardware recognition was failing, because strace showed it was trying to use an NEC scanner.

Then I thought /dev was screwed up because there is no /dev/usb/, no /dev/scanner - but apparently nowadays devices work through libusb.

Finally on the sane web site I found a pointer to the sane-find-scanner command, and since it correctly found and identified my Acer scanner I figured it had to be sane itself the had gone insane.

Cheers