Re: [Qemu-devel] apparently missing yet another notify_event()

[Michael Tokarev <mjt@tls.msk.ru>]

On 14.09.2012 18:17, Michael Tokarev wrote:
> On 04.09.2012 10:58, Michael Tokarev wrote:
>> On 04.09.2012 10:53, Paolo Bonzini wrote:
>>> Il 03/09/2012 20:13, Michael Tokarev ha scritto:
>> []
>>>>  qemu -nographic -kernel /boot/vmlinuz-$(uname -r) -append console=ttyS0 -serial pty
>>>>
>>>> This will hang with 100% CPU usage until something is sent
>>>> to the pty.  <Enter> key is enough.
>> []
>>> Could it be this one?
>>>
>>> <http://permalink.gmane.org/gmane.comp.emulators.qemu/168209>
>>
>> Removing this "pending" initialization fixes this problem too.
> 
> Actually it is not the same thing, and applying this path
> does not solve the originak issue for me, neither does
> updating to 1.2.0 help.
> 
> But it looks like I wasn't correct with the initial diagnostic.
> Qemu (either 1.1 or 1.2) just sleeps for a few moments (about
> 2 seconds) after startup with my command line option, and I
> thought it is stalled.
> 
> The actual problem appears to be qemu-kvm-specific, it does not
> affect qemu (with or without -enable-kvm).
> 
>  qemu-kvm -nographic -kernel /boot/vmlinuz-$(uname -r) -append console=ttyS0 -serial pty
> 
> This hangs till I send a char to the pty.

And it is even _more_ twisted than that.

It depends on the timing.  If I connect to the pty "too soon",
it will not stall.

But if I wait for ~2 seconds or more before connecting, both
qemu and qemu-kvm (and so current qemu/master too) will hang,
requiring a keypress on the pty for the guest to start booting.

Hwell.

/mjt