Re: [Qemu-devel] [PATCH] display: stop using DT_NOGRAPHIC, use DT_NONE

["Andreas Färber" <afaerber@suse.de>]

Am 28.06.2013 13:50, schrieb Michael Tokarev:
> 28.06.2013 15:45, Andreas Färber пишет:
>> Am 28.06.2013 13:29, schrieb Michael Tokarev:
>>> 28.06.2013 15:24, Peter Maydell wrote:
> []
>>>> ...in particular I don't think "-display none" should
>>>> mean "don't allow ctrl-c" (though -nographic should
>>>> continue to have that effect), and this patch currently
>>>> introduces that behaviour change.
>>>
>>> As Anthony said before, -nographic is legacy.  So there should
>>> be some more modern way to control this.  That's exactly the
>>> change which I don't like myself.  
>>
>>> But "don't allow ctrl-c"
>>> which is currently bound to -nographic is equally wrong.
>>
>> What's wrong about that? Isn't Ctrl+C passed through to the guest in
>> -nographic mode? I don't see how any other mode inclusing daemonize
>> would need that.
> 
> Um. With either -nographic or -display none, there's no "display"
> per se, and it is the "display" who relays keypresses and such into
> guest.  Without display, the guest becomes headless completely, not
> only it does not have a monitor of a video card, but also does not
> have keyboard or mouse or other similar stuff.  Or it may have these,
> but you can't "touch" neither keyboard nor mouse because you don't
> "see" them without a display.  Fun thing but here we go.

BTW just try it out using the following to see for yourself:

$ qemu-system-ppc -nographic

should get you to an interactive OpenBIOS prompt. Same for sparc.
This involves communicating to firmware that we are in -nographic mode,
which then redirects its output to serial rather then VGA (think of
sgabios in x86 terms).

Andreas

> 
> This ctrl+c handling is only about when you explicitly redirected
> some other char device to guest, such as serial port.  Which don't
> have much to do with display I think, hence I don't understand the
> logic here.
> 
> Thanks,
> 
> /mjt
> 


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