[sane-devel] Help with ppdev /dev/parport0 on Mandrake Linux 9

[Ryan Harkin]

On Wednesday 23 October 2002 07:07, Mark wrote:
> Help with.
> 1. setting up the parallel port so that non-root users can use it

You need to create the /dev/parportX devices under Mandrake.  When I was 
testing my scanner under Mandrake, I created /dev/parport0 manually using 
mknod:

	# mknod /dev/parport0 c 99 0

However, after playing with the printer config utilities and doing some other 
playing about Mandrake created /dev/parport1..9 without me noticing.

They were softlinks to /dev/parport/[1..9] or /dev/parport/parport[1..9] or 
something like that.  If you can't figure out how to create the softlinks, 
the mknod command should be OK.


> 2. If solution 1 involves module ppdev, then how to stop the hanging.
>
>
> Mandrake kernel is 2.4.19-16. I have read on a previous umax post about
>
> " I assume you are using a kernel version >2.4.18. Since 2.4.19, and the
> introduction of O_NONBLOCK semantics in /dev/parport"
>
> and would like to know if there is a fix workaround for this.

Stef, Tim Waugh and I are having a discussion over on linux-parport 
(http://www.torque.net/linux-pp.html) about the kernel changes since 
2.4.18.0; they break the SANE backend for UMAX parallel port scanners and may 
also break other parallel port backends unless they are coded to use 
non-blocking reads.

I have temporarily modified the Umax backend to use non-blocking reads with 
some success but Stef hasn't verified if this works for him yet, so our ideas 
are still in the formative stages.  And besides, that is a flakey workaround, 
not a fix!

So, to use ppdev, you either need to follow our thread on linux-parport and 
join in the fun or download kernel 2.4.18.

Cheers,
Ryan.