1. Linux and KVM switches!
A lot of people have trouble with wheel mice on Linux when they use
a KVM switch. These are the most common two problems:
1. When you switch to Linux, the wheel does not fully work. E.g., on mine
at work, it can scroll down but not up.
2. Moving the mouse causes the cursor to jump wildly, and also makes it act
as if buttons are being rapidly pressed. The result is that you often
launch many things from you launch panel thingy.
Here is what is odd about this problem.
1. It doesn't seem to be a problem with the mice or KVMs, because they don't
have this problem with Windows or Mac.
2. It doesn't seem to happen all the time. E.g., at home, I have WinXP Pro
and Linux on a 2 port Belkin SOHO switch. I have no problem, other than
sometimes the mouse sensitivity changes under Linux. I never lose the wheel
or get the eratic behaviour. At work, however, with WinXP Pro, Linux (same
distribution), and OS X on a 4 port Belkin, I lose half the wheel almost all
the time, and get the erratic behavior half the time.
Some people report that if they have an unused port on their KVM, switching
to Linux, then switching to the unused port, then back to Linux, is more
reliable. What I've found on my work system is that if I use ALT-Fn to get
out of X before switching away, and then when coming back, switch to Linux,
move the mouse, switch away, switch back, move the mouse again, and then hit
F7 to go back to X, I'm OK.
That's quite a hassle! I did some Googling today, and saw a post on some
web discussion board from someone who talked about the character sequences
that are sent to the mouse to configure it. Based on what he said, I offer
the following program, which fixes my mouse on Linux at work!
int main( void )
{
char c[2] = { 255, 255 };
int fd = open( "/dev/mouse", 1 );
if ( fd >= 0 )
{
write( fd, c, 2 );
close( fd );
}
return 0;
If I switch back to Linux, and there is any mouse problem, I run that as
root, and the problem is fixed.
So, if you have a KVM and are having Linux mouse problems, try taking that
code, putting it an file, say "fixmouse.c", and compiling (gcc -o fixmouse
fixmouse.c). Put fixmouse somewhere in your path, and become root, and do
this from wherever you put it:
chmod root fixmouse
chmod 4555 fixmouse
If you are using a window manager that lets you assign hotkeys to run
programs, assign a hotkey to run fixmouse, and hit that hotkey whenever you
switch back to Linux.
If your distribution does not link /dev/mouse to whatever your mouse device
is, change the open() call to open whatever your mouse device is.
Now...if someone could tell me *why* this isn't needed in Windows and OS X,
I'll be fully happy.
--
Evidence Eliminator is worthless: "www.evidence-eliminator-sucks.com"
--Tim Smith
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