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[Qemu-devel] Re: [PATCH] No keyboard / mouse after reboot
From: |
Dinesh Subhraveti |
Subject: |
[Qemu-devel] Re: [PATCH] No keyboard / mouse after reboot |
Date: |
Mon, 13 Jul 2009 18:42:01 -0700 |
"Anthony Liguori" <address@hidden> wrote in message
news:address@hidden
> Needs a Signed-off-by. However...
>
> Dinesh Subhraveti wrote:
>> At system initialization, some guests conclude that i8042 controller is
>> missing when the PS2 buffer is full. As a result, the guest comes up
>> with no keyboard or mouse. The behavior is seen when the user types or
>> mouses over the VNC window during the BIOS phase of a reboot, causing the
>> PS2 buffer to fill up. It doesn't occur when the system boots the first
>> time, since the device is initially disabled and doesn't accept events.
>> This patch tunes Qemu parameters to reasonable values which make the
>> guest happy. Linux assumes the size of PS2 buffer to be 16 bytes, while
>> Qemu defines it as 256. Reducing PS2_QUEUE_SIZE to 15 ensures that the
>> guest never sees the buffer to be full.
>
> Why is Linux making assumptions about queue size being 16? It sounds
Good question, for which I don't know the answer. But regardless of the
buffer size, it fills up quite quickly with mouse events, and the guest
would be left without a keyboard.
> broken to me. In fact, I looked in one of my PC hardware books and it
> claims that the typical KBD buffer size is around 20 bytes so if Linux is
> assuming 16, it's definitely broken.
>
> But there's speculation in the previous thread that we're masking a BIOS
> bug. Has that been ruled out?
>
Yeah, this doesn't seem to be a BIOS issue. It is also reproducible
with -kernel option.
Thanks,
Dinesh