Re: [Qemu-devel] [PATCH] No keyboard / mouse after reboot

[Anthony Liguori]

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 
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?

Regards,

Anthony Liguori