[Linux-parport] ppdev and kernel panic

Nate Jenkins nate at uniwest.com
Mon Apr 19 12:37:11 BST 2004

I noticed something else that maybe of interest.  It may not have to do with
the claim as much as with what is on the status pins.

I tried to load 'ppdev' with and without the parallel port cable and it
looks like it may have something to do with it.  With the cable on, it will
not shut down correctly, but without, it seems to shutdown fine.

Last week, it was the opposite, with the cable it was fine but without it
would kernel panic after "halt".

What does this indicate?  Something to do with the ~BUSY or ACK bit state
maybe when releasing?


----- Original Message ----- 
From: "Nate Jenkins" <nate at uniwest.com>
To: "Parport" <linux-parport at lists.infradead.org>
Sent: Monday, April 19, 2004 10:52 AM
Subject: [Linux-parport] ppdev and kernel panic

> Hello,
> I have seen a problem which I do not know if it has been fixed or not.
> I am using a relatively old/ancient kernel.  Kernel 2.4.2-2 which is Red
> 7.1.  This kernel has built into it 'parport.o' and 'parport_pc.o'
> statically.
> OK, I have had a program working which will automatically switch between
> 'ppdev.o' and 'lp.o'.  That is to say, my code will "insmod ppdev" or
> "insmod lp".  When switching the code will respectively "rmmod lp" or
> ppdev".  Everything is successful in the ioctl functions and with using
> modules to communicate via parallel port.
> The problem is when I shutdown the computer.  If I never use 'ppdev' in a
> session, it will shutdown fine.  If I load 'ppdev' at anytime in the
> session, then the pc will fail to shutdown correctly.
> I can tell that no modules are inserted into kernel via "lsmod" before I
> "halt" the computer.
> Does anyone know what maybe happening here?  Or can I clarify anything I
> have failed to make clear?
> It seems that it might be related to claiming the port.  If I do not
> the port I do not have this issue.  However, I cannot do my communication
> without claiming it.  So I am claiming it.  I am also releasing it at the
> end.  Although the ioctl returns zero, I think it isn't really releasing
> thus causing the kernel panic.
> If I can compile the ppdev module with new source and it works, then, that
> would be a valid solution for me.  I would really like to know what is
> on though.
> Nate
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> Linux-parport at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-parport

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