[winswitch] xpra dpi woes with a server running Ubuntu cosmic

Antoine Martin antoine at nagafix.co.uk
Thu Sep 13 09:52:03 BST 2018

On 12/09/2018 19:43, Perry E. Metzger wrote:
> On Wed, 12 Sep 2018 19:17:36 +0700 Antoine Martin via shifter-users
> <shifter-users at lists.devloop.org.uk> wrote:
>> On 12/09/2018 18:55, Perry E. Metzger via shifter-users wrote:
>>> Howdy! I'm testing out xpra with a remote server running
>>> Ubuntu Cosmic and a client running MacOS, and I've been having
>>> some challenges with the setup setting the DPI to weird values.  
>> What values and where did you find them?
> I found the values in the log. Opening up applications leads to crazy
> display sizes, and I saw this:
> 2018-09-11 20:54:07,844 client @18.265 Xpra X11 server version 2.3.2-r19729 64-b
> it
> 2018-09-11 20:54:07,845 client @18.266  running on Linux Ubuntu 18.10 cosmic
> 2018-09-11 20:54:07,849 DPI set to 17 x 21 (wanted 72 x 72)
> 2018-09-11 20:54:07,849  you may experience scaling problems, such as huge or sm
> all fonts, etc
> 2018-09-11 20:54:07,849  to fix this issue, try the dpi switch, or use a patched
>  Xorg dummy driver
Right, that's the simulated "hardware DPI" that some applications use.
Out of curiosity, which application misbehaved?

(everything would be much easier if they just used some
user-configurable value like Xft/DPI instead)

>>> My impression from reading old trouble tickets is that I need to
>>> install a patched version of the Xdummy stuff but I'm not exactly
>>> sure. What do I need to do, roughly? (I searched and couldn't
>>> really find exact instructions...)
>> Everything you need should be here:
>> http://xpra.org/trac/browser/xpra/trunk/debian/xserver-xorg-video-dummy
> Do I just patch xserver-xorg-video-dummy with what's in patches/ ?
> I presume I can use the Ubuntu source package to do this?

> Is there a chance of contributing these patches upstream? It would
> help.
That's very very unlikely to be merged upstream.
The DPI patch is really hackish.

> And can I install the patched Xdummy somewhere non-standard and point
> xpra at it? I imagine that something in /etc/xpra/* will let me do
> that but I don't know how.
You can use ModulePath in xorg.conf:

>> As the Ubuntu 18.10 release nears, we will start pushing packages
>> to the beta repository, this will include the patched dummy driver.
>> Until then, you will need to compile the driver yourself or use
>> another workaround.
I have started pushing packages to the xpra "cosmic" repositories,
including the patched dummy driver. Simply adding the repository and
updating should give you all you need.

If those packages work for you, please comment or close this ticket:


> Perry

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