Re: which driver ?

Matto Marjanovic (maddog@mir.com)
Wed, 1 Jul 1998 15:57:58 -0400 (EWT)

[Anyone have any clues/suggestions as to what is going on?
The hardware involved is a Microtek 600GS scanner, with the classic
Adaptec AVA-1502 scsi card, Linux 2.1.107.
The weird part: scanimage works as non-root, but hangs as root.]

> Date: Wed, 01 Jul 1998 18:06:57 +0200
> From: Oliver Neukum <neukum@fachschaft.org.chemie.uni-muenchen.de>

> Hi Matto,
> i fear i have more bad news for you.
> The scanner's firmware has a bug, it crashes when a lun>0 is referred to.

Not so unexpected....

> I s this done within SANE ? Might it explain hangs as root ?
> Do you need any more information ?
> A patch against kernel 2.1.107 is attached.

Isn't there also a kernel configuration option to disable scanning
all LUNs? That's usually what you want, unless you have a multi-platter
CDROM that actually uses them... (Either way, I'll put this info somewhere
on my web page.)

> i can confirm that my inabillity to scan as root is caused by sane touching
> luns>0.
> The patch to the kernel, which i sent you yesterday allows scanimage to work.

Can you tell where this happens? The microtek backend shouldn't touch any
LUN other than 0 --- is this some other backend? (Are the others commented
out of dll.conf?)

Also, the "BLIST_NOLUN" designation in the patch only affects how the
mid-level scsi driver scans the scsi bus --- thus your patch should only
affect what happens a) when machine boots, b) when a scsi driver module
is loaded. SANE doesn't cause either, unless you have kerneld set up to
automatically load the scsi modules.

And... I don't see how any part of SANE does anything differently whether
or not it is used as root. SANE's only interaction with the Linux system
is to open/read/write/close the sg devices (which is affected by their
permissions), and open/read/close "/proc/scsi/scsi". Since you can scan
as non-root, SANE as root would only be touching *other* sg devices
differently.

Hmm... of course, I'm looking at 2.0.33 kernel code --- maybe the scsi bus
is rescanned in the 2.1.107 code? Some drastic difference?

-matt m.

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