[a step closer?] Erratic PS/2 mouse since 2.1.126

Mike McEwan (mike@lotusland.demon.co.uk)
Sun, 10 Jan 1999 14:57:53 GMT


Well, I've been trying to nail this one for a month or so. I have a
Microsoft Intellimouse on my PS/2 port. This was working just fine
until psaux.c was merged with pc_keyb.c at 2.1.126 (IIRC). Since then
I have been experiencing erratic mouse behaviour when I'm online to my
ISP - the mouse will shoot up to the top right-hand corner of my
screen under X, and takes a little coaxing to get it down again
(sometimes X locks altogether).

As the problem only appeared to happen when my modem was actively
transmitting/receiving, I thought it might be something to do with
IRQs, `setserial' or 'irqtune'. Elimination of each of these factors
had no effect. I also tried killing `gpm' when under X.

In hindsight it is a little embarassing that I didn't happen upon
this before, but I use a program callled `netkbd' to flash my
keyboard's leds when there is activity over my modem - killing this
has seemingly fixed the problem!

`netkbd' flashes the keyboard leds via calls to ioctl:

void capson(void)
{
ioctl(ttyfd,KDGETLED,&savedleds);
ioctl(ttyfd,KDSETLED,savedleds^LED_CAP);
}

void capsoff(void)
{
ioctl(ttyfd,KDGETLED,&savedleds);
ioctl(ttyfd,KDSETLED,savedleds&~LED_CAP);
}

As yet I'm still very wet behind the ears as regards the kernel
sources, but is this maybe something to do with spinlock/IRQ
mechanisms being bypassed when the keyboard is read from/written to in
this way?

Any pointers much appreciated.

-- 
Mike.
.

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