sane-project-backends/PROBLEMS

Last update: Sun Nov 12 16:47:01 CET 2000

- Compiling SANE aborts with error "virtual memory exhausted" on Slackware
  linux with gcc. What goes wrong?

  The optimization set by "-O2" makes problems, try which one of the
  following calls work:

	make CFLAGS="-g -Wall -O1"
	make CFLAGS="-g -Wall -O"
	make CFLAGS="-g -Wall"

- Avoiding damage on Mustek flatbed scanners
	Most Mustek flatbed scanners have no protection against exceeding
	the physical scan area height.  That is, if a scan is attempted with
	a height that exceeds the height of the scan surface, the scanner
	begins making loud noises and the scan mechanism may be damaged.
	Thus, if you hear such a noise, IMMEDIATELY turn off the scanner.

	Normally, the Mustek backend will ensure that the maximum scan
	height is not exceeded.  However, if your scanner model has not been
	tested yet, this safety-guard may not work.  In such a case,
	you may want to use scanimage's -y option to gradually determine the
	exact height of the scan area (making sure to turn off the scanner as
	soon as it starts making noises).  Once you know the proper height,
	mail the following information to sane-devel@mostang.com:

		- scanner name (labels on the front and back of the scanner)
                - debug logfile

	To get the debug logfile enter the following:

		SANE_DEBUG_MUSTEK=5 scanimage -L 2>logfile.txt

	The current list of Mustek scanners that are known to work
	properly can be found in man-page sane-mustek(5).

- My Linux box used to scan just fine but now it suddenly won't work anymore,
  what's up?
	If you increased SG_BIG_BUFF when building SANE (as is recommended
	by sane-scsi(5) for performance reasons), be careful when upgrading
	the kernel as that will typically install a new version of
	/usr/include/scsi/sg.h, with the old, smaller value.  This has
	the effect that SANE _thinks_ the SCSI buffer is big, but since
	the Linux kernel uses a smaller value, scanning will fail with
	"out of memory" errors.  To fix this problem, increase SG_BIG_BUFF
	to the old value, rebuild the kernel, then reboot the machine
	Newer versions of SANE (>1.01) tries to read the current
	SG_BIG_BUFF from /proc/sys/kernel/sg-big-buff which is
	available with newer linux kernels (>= v2.2).

- Missing /usr/include/scsi on Linux systems
	Older Linux distributions are missing the /usr/include/scsi directory.
	In such a case, it is necessary to copy the relevant files from
	the kernel distribution.  Normally, the command:

		cp -a /usr/src/linux/include/scsi /usr/include

	should fix this problem.

- Security problems with pnm
        If the pnm backend is installed and saned is used to allow users on
        remote computers to scan on the local machine, pnm files can be read by
	the remote user. This is limited to the files saned can access (usually
        it's running as user "sane"). All pnm files can be read if saned runs
        as root which isn't recommended anyway. The pnm backend is disabled
        by default. If you want to use it, enable it with configure (see 
        configure --help for details). Be sure that only trusted users can
	access the pnm backend over saned.