Re: [Qemu-devel] [PATCH v3] ps2: set ps/2 output buffer size as the same as kernel

[Amos Kong]

On Sat, Apr 26, 2014 at 06:21:18AM +0000, Gonglei (Arei) wrote:
> Hi,
> 
> > On Thu, Apr 24, 2014 at 08:06:19PM +0800, address@hidden wrote:
> > > From: Gonglei <address@hidden>
> > >
> > > According to the PS/2 Mouse/Keyboard Protocol, the keyboard outupt buffer
> > size
> > > is 16 bytes. And the PS2_QUEUE_SIZE 256 was introduced in Qemu from the
> > very
> > > beginning.
> > >
> > > When I started a  redhat5.6 32bit guest, meanwhile tapped the keyboard as
> > quickly as
> > > possible, the screen would show me "i8042.c: No controller found". As a
> > result,
> > > I couldn't use the keyboard in the VNC client.
> > >
> > > Previous discussion about the issue in maillist:
> > > http://thread.gmane.org/gmane.comp.emulators.qemu/43294/focus=47180
> > >
> > > This patch has been tested on redhat5.6 32-bit/suse11sp3 64-bit guests.
> > > More easy meathod to reproduce:
> > > 1.boot a guest with libvirt.
> > > 2.connect to VNC client.
> > > 3.as you see the BIOS, bootloader, Linux booting, run the follow simply 
> > > shell
> > script:
> > > for((i=0;i<10000000;i++)) do virsh send-key redhat5.6 KEY_A; done
> > 
> > Why we can't break keyboard by flooding input after boot up?
> > 
> Actually, I have pointed the root reason about this issue in other email.
> 
> When the linux kernel booting, will init the i8042 controller 
> (drivers/input/serio/i8042.c), and 
> check the i8042 controller:
> i8042_init() 
>       |-> i8042_controller_check()
> 
> If the kernel has booted up, the check will not happen, so the Linux kernel 
> will not get confused.
 
I didn't find that the checking is necessary in protocol docs.
any hint?

If we still use 256 size buffer in qemu, guest ps2 driver will drop
some input keys? or just delay them?

Thanks
 
> Best regards,
> -Gonglei

-- 
                        Amos.