cups 1.4.3 usb backend fails to detect printers.

Naveen Krishna naveen.yarlagadda at patni.com
Wed Dec 15 07:31:59 PST 2010


hi,
 I have encountered a problem with the 'usb' backend of cups 1.4.3. The backend is not able to detect the USB printer (HP LaserJet 1320). If I specify "--disable-libusb" while configuring cups, it is detecting the devices.

The details of the shared libs for the usb backend executable with & without libusb are as follows resp.

(without libusb)
linux-gate.so.1 =>  (0xffffe000)
libcups.so.2 => /usr/lib/libcups.so.2 (0xb7857000)
libgnutls.so.26 => /usr/lib/libgnutls.so.26 (0xb77da000)
libpthread.so.0 => /lib/libpthread.so.0 (0xb77c1000)
libm.so.6 => /lib/libm.so.6 (0xb779b000)
libcrypt.so.1 => /lib/libcrypt.so.1 (0xb7768000)
libc.so.6 => /lib/libc.so.6 (0xb7622000)
libz.so.1 => /usr/lib/libz.so.1 (0xb760e000)
libgcrypt.so.11 => /usr/lib/libgcrypt.so.11 (0xb75a3000)
libgpg-error.so.0 => /usr/lib/libgpg-error.so.0 (0xb759f000)
/lib/ld-linux.so.2 (0xb7892000)

(with libusb)
linux-gate.so.1 =>  (0xffffe000)
libusb-0.1.so.4 => /usr/lib/libusb-0.1.so.4 (0xb76e7000)
libcups.so.2 => /usr/lib/libcups.so.2 (0xb76b0000)
libpthread.so.0 => /lib/libpthread.so.0 (0xb7697000)
libm.so.6 => /lib/libm.so.6 (0xb7671000)
libcrypt.so.1 => /lib/libcrypt.so.1 (0xb763e000)
libc.so.6 => /lib/libc.so.6 (0xb74f8000)
libusb-1.0.so.0 => /usr/lib/libusb-1.0.so.0 (0xb74ec000)
libz.so.1 => /usr/lib/libz.so.1 (0xb74d8000)
/lib/ld-linux.so.2 (0xb76ef000)
librt.so.1 => /lib/librt.so.1 (0xb74cf000)

 I am not sure why 2 versions of libusb are linked. but the difference i observed with them is usr/lib/libusb-1.0.so.0 has no function usb_init().

 Also, when using the libusb, the o/p observed when the usb backend executable run from the command prompt.
DEBUG: list_devices
DEBUG: usb_find_busses=4
DEBUG: usb_find_devices=6

But when seen in the cups error_log, it is something like
[Job 41]list_devices
[Job 41]usb_find_busses=0
[Job 41]usb_find_devices=0
Waiting for printer to become available...

 I would appreciate any help in this regard. Thanks in advance..

--Naveen




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