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Re: PS/2 emulation - timer?

From: Jakob Bohm
Subject: Re: PS/2 emulation - timer?
Date: Tue, 3 Nov 2020 00:10:02 +0100
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On 2020-11-02 23:25, Peter Maydell wrote:
On Mon, 2 Nov 2020 at 21:44, Kamil Jońca <kjonca@poczta.onet.pl> wrote:

As I wrote earlier there is strange behavior of ps/2 mouse emulation
I tried to read code
(https://github.com/qemu/qemu/blob/master/hw/input/ps2.c) but cannot
find anything wrong. The only thing I doubt is time relation issues
(ps/2 description mentions about sample rate), but this was rather quick look.
Not sure. But as a general rule of thumb, you're better off
going with an absolute-position device (the standard one is
the USB tablet device) rather than a relative-position one
like the PS/2 mouse when you're giving the guest an emulated
pointing device. A relative-position one will always tend to
get out of sync with the host mouse, and an absolute-position
one won't.

-- PMM
Historically, there were some absolute-position devices that used
the PS/2 port.  These were identified by either a special bit in
the position message, or specific responses to an ID query sent
out the PS/2 port.


Jakob Bohm, CIO, Partner, WiseMo A/S.  https://www.wisemo.com
Transformervej 29, 2860 Søborg, Denmark.  Direct +45 31 13 16 10
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