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Date:      Mon, 22 May 2000 13:31:51 -0400 (EDT)
From:      Trevor Johnson <trevor@jpj.net>
To:        Matthew Dillon <dillon@apollo.backplane.com>
Cc:        Garrett Wollman <wollman@khavrinen.lcs.mit.edu>, "Jordan K. Hubbard" <jkh@zippy.cdrom.com>, current@FreeBSD.ORG, Boris Popov <bp@butya.kz>
Subject:   Re: Anyone else seeing jumpy mice?
Message-ID:  <Pine.BSI.4.21.0005221259320.3748-100000@blues.jpj.net>
In-Reply-To: <200005221651.JAA60866@apollo.backplane.com>

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Matthew Dillon wrote:

> :> May 19 00:50:45 zippy /kernel: psmintr: out of sync (00c0 != 0000).

>     Now, I must say, that there is no way we are going to add that hack back
>     in ... it was a real mess and is simply not worth it, and when we 
>     move to the interrupt threading model we can truely make the serial 
>     interrupt SMP-safe and do away with the issue once and for all.

Looking at the old driver (src/sys/i386/isa/Attic/psm.c,v) I see a note
that the hardware offers a polling mode (not implemented in that driver),
where the mouse only sends packets after getting requests for them.  If
there are intractable problems with handling interrupts, perhaps that mode
could be used instead (maybe if no one had used the mouse recently,
polling could be done less often, to conserve CPU time).

>     I don't know if the mouse problems are related or not, did anyone have
>     jumpy-mouse problems before the SMP cleanup was committed? (i.e. in
>     kernels then two weeks old for 4.0, and four weeks old for 5.0).

I'm running 4.0-STABLE from May 5 23:39 PDT and I found one of those
messages (just like Jordan's except for the hostname and time). I think I
was at the computer when it happened, but I don't remember any erratic
movement of the mouse pointer, nor have I ever noticed any under FreeBSD.  
I have XFree86 3.3.6 running from xdm, using /dev/sysmouse as the mouse
device.  I have moused running too, and was probably in text mode when the
tragedy^H^H^H^H^H^H^H error message happened. My computer has a Digital
Equipment Corp. PC7XS-CA three-button mouse, a Winbond W83977TF-AW I/O
chip, and Intel 440 BX chip set.

I saw this problem a long time ago, most memorably on an IBM PS/2 55SX
with an IBM mouse, under Windows 3.0.  Sometimes the mouse pointer would
move suddenly all around the screen, and programs would behave as though
someone were pressing the mouse buttons. Searching the Web, I see that the
Linux folks have had the problem too:

http://www.tux.org/hypermail/linux-kernel/1999week01/0953.html
http://gwyn.tux.org/hypermail/linux-kernel/1999week03/0435.html

One wanted to program the remote (polling) mode:
http://www.linuxhq.com/guides/KHG/HyperNews/get/khg/333.html
.
--
Trevor Johnson
http://jpj.net/~trevor/gpgkey.txt



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