Re: [Qemu-devel] [BUG] GTK terminal is broken

[Stefan Weil <sw@weilnetz.de>]

Am 29.07.2013 22:34, schrieb Andreas Färber:
> Am 29.07.2013 21:27, schrieb Stefan Weil:
>> Am 29.07.2013 20:55, schrieb Anthony Liguori:
>>> Stefan Weil <sw@weilnetz.de> writes:
>>>
>>>> Am 29.07.2013 20:05, schrieb Anthony Liguori:
>>>>> Stefan Weil <sw@weilnetz.de> writes:
>>>>>
>>>>>> Hello,
>>>>>>
>>>>>> maybe most developers will already have noticed that the terminal output
>>>>>> in QEMU's GTK user interface is broken. As far as I know, it never worked,
>>>>>> but as there are working alternatives, I did not care much and forgot to
>>>>>> report the issues.
>>>>>>
>>>>>> See these snapshots which show the problems with QEMU's GTK terminals:
>>>>>>
>>>>>> http://qemu.weilnetz.de/test/bugs/qemu-gtk-demo1.png
>>>>>>
>>>>>> Here the first line of the QEMUmonitor is only partially visible.
>>>>>> Tested with Cygwin/X on W64 host, QEMU running on Debian Linux.
>>>>>> Other X servers (e.g. native X on Debian Linux) don't show this
>>>>>> problem.
>>>>> It's a GTK/Cygwin/X bug.
>>>>>
>>>>> We use a vbox without anything particularly fancy happening.  Looks like
>>>>> something is calculating layout incorrectly.
>>>>>
>>>>> Regards,
>>>>>
>>>>> Anthony Liguori
>>>> I miss a comment on the more important next two points.
>>>> They are _not_ related to Cygwin / X.
>>>>
>>>> Do you investigate them?
>>> What you're seeing has always existed and is not GTK specific.  There is
>>> not flow control on the outgoing side of serial emulation.  Data will
>>> get dropped.
>>>
>>> My guess is that your system is sufficiently slow and overloaded that
>>> it's happening a lot for you.
>>>
>>> Regards,
>>>
>>> Anthony Liguori
>> If it were as simply as that, that would be fine, but alas,
>> it isn't. Even fast servers without any load show dropped
>> characters. There are dropped characters for QEMU's
>> monitor window (Alt-ctrl-2) and for Malta's line display
>> (Alt-Ctrl-5). Neither of these two should suffer from missing
>> flow control.
>>
>> And even a current X.Org on Ubuntu shows the first bug
>> (crippled first line) here, so it is not Cygwin / X specific.
> FWIW I've been seeing similar garbled-Gtk-output issues on openSUSE 12.3
> but didn't investigate further. -monitor stdio has so far not failed me
> on the same system by comparison.
>
> One reproducible test case was the openrisc kernel that Jia provided
> recently.
>
> Regards,
> Andreas

Maybe the problems only occur with TCG, but not with KVM.
That might explain why I get them more often than Anthony :-)

Up to now, I did not try GTK terminals with KVM because my
typical test scenario uses MIPS or ARM boards on Intel hosts.

Regards,
Stefan