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List: kde-buildsystem
Subject: Re: Review Request 125163: Disable X11,XCB etc. detection on OS X
From: "Alex Merry" <alex.merry () kde ! org>
Date: 2015-09-23 19:54:19
Message-ID: 20150923195419.14939.73609 () mimi ! kde ! org
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> On Sept. 13, 2015, 9:52 a.m., Martin Gräßlin wrote:
> > I'm in favor of the approach as this solves the problem that again and again [1] \
> > we have attempts of OSX-specific disabling of X11 in various frameworks and \
> > applications.
> > The big problem on OSX seems to be that one doesn't want suport for X11, as it's \
> > not the windowing system. The code we have in our frameworks which is X11 \
> > specific performs runtime checks, thus is dead code on OSX anyway. For (to me \
> > unknown) reasons X11 gets pulled in during build on OSX though, causing either \
> > useless or crashy code to be included. Thus there are attempts to patch the \
> > frameworks instead of just fixing the cmake build command.
> > I understand that it's a behavior change and thus dangerous. But that's the same \
> > for each framework which gets "fixed" in the way I describe above. In the end \
> > from what I understood from our OSX devs: they don't want X11 and it's from their \
> > perspective a bug that it gets picked up. To me it sounds like we should really \
> > break our rules to provide an overall better product. Thousand micro-edits in the \
> > frameworks are more dangerous than the one time explicit break.
> > For what is worth I suggest that a warning could be printed by CMake, that those \
> > modules are not searched for and what's the command to override it.
> > [1] There is already a huge list of reviews which I blocked because they were \
> > just wrong, but there are probably way more frameworks which got "fixed" where I \
> > just didn't notice the review.
>
> Samuel Gaist wrote:
> Getting X11 in the process is pretty easy: install ffmpeg with macports and you \
> have it in (or at least parts of it).
> One problem I see about X11 on OS X is that it's not an official or tested platform \
> for Qt and like you said most of the code already disables it at run time in KDE. I \
> don't know the effort (in man power) needed to support it properly. I think that \
> would mean at least having a CI building Qt 5 and running tests for that combo to \
> ensure everything is running fine from a Qt point of view.
> @martin, can you share that list ? It could help speed things up to build a full \
> KDE on OS X
> Allen Winter wrote:
> right. I wouldn't object to going even further than this patch: Don't check for X11 \
> on MAC. make sure FOUND_X11 is always FALSE. Just like you wouldn't check for X11 \
> on Windows.
> Martin Gräßlin wrote:
> > @martin, can you share that list ? It could help speed things up to build a full \
> > KDE on OS X
>
> sorry, I don't track them and wouldn't know how to find it quickly. In the end I \
> don't think it matters to know those. Specify no X11 and all is fine.
> Alex Merry wrote:
> Martin: I'm not opposed to the change as such, but as you note, it is potentially \
> dangerous. I just want to get an idea of whether changing the default behaviour \
> like this is likely to cause issues for anyone. Is building Qt-based software with \
> X11 support on OS X a use case anyone really cares about? If so, who, and why?
> Allen: that's pretty much what this patch is doing.
>
> René J.V. Bertin wrote:
> Guys, can you please add the kde-mac group when discussing things that concern OS \
> X?! It's only by accident that I've come across this change.
> To answer a few open questions: X11 is not at all an unusual environment on the \
> machines of users who are (most?) likely to have an interest in KDE applications (4 \
> or 5 or even 3). Installing port:ffmpeg (= MacPort's ffmpeg port) with the default \
> X11 variant is indeed a way to get it installed, but if others are like me they \
> also use a selection of X11/Gtk/Gnome applications and maybe even run an XQuartz \
> session all the time. I know I'm not even alone in using xterms :)
> So yes, it's been a recurrent "fight" to get rid of X11-specific code that kept \
> popping up in KDE4 sources and build systems in part because not every KDE \
> developer was bothered keeping clearly platform-specific code inside #ifdefs or \
> separate modules. With KDE4/Qt4 the situation was simple: Qt4 cannot be built for \
> Darwin/X11 anymore since 4.6 or 4.7 . With Qt5's QPA architecture this is possible \
> again, though not officially supported. It is even possible to build just QtBase \
> for xcb and then install only the xcb plugin and its dependencies into the Cocoa \
> build/install, and run applications over X11 (even remotely as long). My own \
> port:qt5-kde (Qt5 port with a number of patches that improve the KDE experience, \
> based on my experience with KDE4) offers a mechanism to do just that.
> That doesn't mean KDE applications should detect X11/xcb and include code that's \
> specific to that platform. As long as they don't invoke "native" APIs directly for \
> displaying purposes they should benefit from Qt's xcb support if a user wants that. \
> The prospect of being able to open KDevelop remotely on my Linux netbook appeals \
> much more to me than going through VNC, for instance (huge screen size \
> differences).
> What is the official dogma on using platform-specific code for displaying purposes? \
> Outside of clearly X11-specific contexts like KWin, are developers free to use X11 \
> calls when they prefer them over the Qt equivalents, or are there strong guidelines \
> to avoid that or wrap such sections in #ifdefs?
> > Is building Qt-based software with X11 support on OS X a use case anyone really \
> > cares about? If so, who, and why?
>
> In short, yes, me and at least 1 person from Fink. But only as far as a reasonable \
> effort to have Qt-based software that also runs when started with `-platform xcb`.
> I probably wouldn't mind at all if it were possible to build a full X11-based KDE \
> (4 or 5) desktop to run in a rooted X11 window, meaning you can toggle between an \
> OS X desktop and a KDE desktop (or between a "PC" and a Unix workstation...) with \
> just a keyboard shortcut. But that's just not feasible.
Ah, I didn't think that there might be a mac-specific group to add. I'll bear that in \
mind for the future.
Ideally, X11-specific code should also be runtime-wrapped in checks for the QPA \
backend (also for Wayland on Linux). Theoretically, it should be possible to build \
KDE software with X11 support on a mac that would work in either mode. I'm not \
exactly sure what the issue with building KCrash on Mac was, but as Samuel Gaist \
noted, we're short on people who care about X11-on-OS-X and have the time and desire \
to work on stabilising that support. Given that, defaulting to the "usual" case (of \
not having X11 support on OS X), which is better tested, seems reasonable.
- Alex
-----------------------------------------------------------
This is an automatically generated e-mail. To reply, visit:
https://git.reviewboard.kde.org/r/125163/#review85307
-----------------------------------------------------------
On Sept. 15, 2015, 10:50 p.m., Samuel Gaist wrote:
>
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://git.reviewboard.kde.org/r/125163/
> -----------------------------------------------------------
>
> (Updated Sept. 15, 2015, 10:50 p.m.)
>
>
> Review request for Extra Cmake Modules.
>
>
> Repository: extra-cmake-modules
>
>
> Description
> -------
>
> Disable X11,XCB etc. detection on OS X
>
>
> Diffs
> -----
>
> kde-modules/KDECMakeSettings.cmake 0c997931abee8673ccecc66d122108c6f72bf9b1
>
> Diff: https://git.reviewboard.kde.org/r/125163/diff/
>
>
> Testing
> -------
>
> KCrash build on OS X 10.8
>
>
> Thanks,
>
> Samuel Gaist
>
>
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This is an automatically generated e-mail. To reply, visit:
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<blockquote style="margin-left: 1em; border-left: 2px solid #d0d0d0; padding-left: \
10px;"> <p style="margin-top: 0;">On September 13th, 2015, 9:52 a.m. UTC, <b>Martin \
Gräßlin</b> wrote:</p> <blockquote style="margin-left: 1em; border-left: 2px solid \
#d0d0d0; padding-left: 10px;"> <pre style="white-space: pre-wrap; white-space: \
-moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: \
break-word;"><p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">I'm in favor of the approach as this solves the \
problem that again and again [1] we have attempts of OSX-specific disabling of X11 in \
various frameworks and applications.</p> <p style="padding: 0;text-rendering: \
inherit;margin: 0;line-height: inherit;white-space: inherit;">The big problem on OSX \
seems to be that one doesn't want suport for X11, as it's not the windowing system. \
The code we have in our frameworks which is X11 specific performs runtime checks, \
thus is dead code on OSX anyway. For (to me unknown) reasons X11 gets pulled in \
during build on OSX though, causing either useless or crashy code to be included. \
Thus there are attempts to patch the frameworks instead of just fixing the cmake \
build command.</p> <p style="padding: 0;text-rendering: inherit;margin: \
0;line-height: inherit;white-space: inherit;">I understand that it's a behavior \
change and thus dangerous. But that's the same for each framework which gets "fixed" \
in the way I describe above. In the end from what I understood from our OSX devs: \
they don't want X11 and it's from their perspective a bug that it gets picked up. To \
me it sounds like we should really break our rules to provide an overall better \
product. Thousand micro-edits in the frameworks are more dangerous than the one time \
explicit break.</p> <p style="padding: 0;text-rendering: inherit;margin: \
0;line-height: inherit;white-space: inherit;">For what is worth I suggest that a \
warning could be printed by CMake, that those modules are not searched for and what's \
the command to override it.</p> <p style="padding: 0;text-rendering: inherit;margin: \
0;line-height: inherit;white-space: inherit;">[1] There is already a huge list of \
reviews which I blocked because they were just wrong, but there are probably way more \
frameworks which got "fixed" where I just didn't notice the review.</p></pre> \
</blockquote>
<p>On September 13th, 2015, 5:08 p.m. UTC, <b>Samuel Gaist</b> wrote:</p>
<blockquote style="margin-left: 1em; border-left: 2px solid #d0d0d0; padding-left: \
10px;"> <pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: \
-pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: \
inherit;">Getting X11 in the process is pretty easy: install ffmpeg with macports and \
you have it in (or at least parts of it).</p> <p style="padding: 0;text-rendering: \
inherit;margin: 0;line-height: inherit;white-space: inherit;">One problem I see about \
X11 on OS X is that it's not an official or tested platform for Qt and like you said \
most of the code already disables it at run time in KDE. I don't know the effort (in \
man power) needed to support it properly. I think that would mean at least having a \
CI building Qt 5 and running tests for that combo to ensure everything is running \
fine from a Qt point of view.</p> <p style="padding: 0;text-rendering: \
inherit;margin: 0;line-height: inherit;white-space: inherit;">@martin, can you share \
that list ? It could help speed things up to build a full KDE on OS X</p></pre> \
</blockquote>
<p>On September 13th, 2015, 8:12 p.m. UTC, <b>Allen Winter</b> wrote:</p>
<blockquote style="margin-left: 1em; border-left: 2px solid #d0d0d0; padding-left: \
10px;"> <pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: \
-pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: \
inherit;">right. I wouldn't object to going even further than this patch: Don't check \
for X11 on MAC. make sure FOUND_X11 is always FALSE. Just like you wouldn't check for \
X11 on Windows.</p></pre> </blockquote>
<p>On September 14th, 2015, 6:11 a.m. UTC, <b>Martin Gräßlin</b> wrote:</p>
<blockquote style="margin-left: 1em; border-left: 2px solid #d0d0d0; padding-left: \
10px;"> <pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: \
-pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><blockquote \
style="text-rendering: inherit;padding: 0 0 0 1em;border-left: 1px solid \
#bbb;white-space: normal;margin: 0 0 0 0.5em;line-height: inherit;"> <p \
style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: \
inherit;">@martin, can you share that list ? It could help speed things up to build a \
full KDE on OS X</p> </blockquote>
<p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">sorry, I don't track them and wouldn't know how to \
find it quickly. In the end I don't think it matters to know those. Specify no X11 \
and all is fine.</p></pre> </blockquote>
<p>On September 14th, 2015, 10:11 a.m. UTC, <b>Alex Merry</b> wrote:</p>
<blockquote style="margin-left: 1em; border-left: 2px solid #d0d0d0; padding-left: \
10px;"> <pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: \
-pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: \
inherit;">Martin: I'm not opposed to the change as such, but as you note, it is \
potentially dangerous. I just want to get an idea of whether changing the default \
behaviour like this is likely to cause issues for anyone. Is building Qt-based \
software with X11 support on OS X a use case anyone really cares about? If so, who, \
and why?</p> <p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">Allen: that's pretty much what this patch is \
doing.</p></pre> </blockquote>
<p>On September 23rd, 2015, 5:28 p.m. UTC, <b>René J.V. Bertin</b> wrote:</p>
<blockquote style="margin-left: 1em; border-left: 2px solid #d0d0d0; padding-left: \
10px;"> <pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: \
-pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">Guys, \
can you please add the kde-mac group when discussing things that concern OS X?! It's \
only by accident that I've come across this change.</p> <p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">To \
answer a few open questions: X11 is not at all an unusual environment on the machines \
of users who are (most?) likely to have an interest in KDE applications (4 or 5 or \
even 3). Installing port:ffmpeg (= MacPort's ffmpeg port) with the default X11 \
variant is indeed a way to get it installed, but if others are like me they also use \
a selection of X11/Gtk/Gnome applications and maybe even run an XQuartz session all \
the time. I know I'm not even alone in using xterms :)</p> <p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">So \
yes, it's been a recurrent "fight" to get rid of X11-specific code that kept popping \
up in KDE4 sources and build systems in part because not every KDE developer was \
bothered keeping clearly platform-specific code inside #ifdefs or separate modules. \
With KDE4/Qt4 the situation was simple: Qt4 cannot be built for Darwin/X11 anymore \
since 4.6 or 4.7 . With Qt5's QPA architecture this is possible again, though not \
officially supported. It is even possible to build just QtBase for xcb and then \
install only the xcb plugin and its dependencies into the Cocoa build/install, and \
run applications over X11 (even remotely as long). My own port:qt5-kde (Qt5 port with \
a number of patches that improve the KDE experience, based on my experience with \
KDE4) offers a mechanism to do just that.</p> <p style="padding: 0;text-rendering: \
inherit;margin: 0;line-height: inherit;white-space: inherit;">That doesn't mean KDE \
applications should detect X11/xcb and include code that's specific to that platform. \
As long as they don't invoke "native" APIs directly for displaying purposes they \
should benefit from Qt's xcb support if a user wants that. The prospect of being able \
to open KDevelop remotely on my Linux netbook appeals much more to me than going \
through VNC, for instance (huge screen size differences).</p> <p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">What \
is the official dogma on using platform-specific code for displaying purposes? \
Outside of clearly X11-specific contexts like KWin, are developers free to use X11 \
calls when they prefer them over the Qt equivalents, or are there strong guidelines \
to avoid that or wrap such sections in #ifdefs?</p> <blockquote \
style="text-rendering: inherit;padding: 0 0 0 1em;border-left: 1px solid \
#bbb;white-space: normal;margin: 0 0 0 0.5em;line-height: inherit;"> <p \
style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: \
inherit;">Is building Qt-based software with X11 support on OS X a use case anyone \
really cares about? If so, who, and why?</p> </blockquote>
<p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">In short, yes, me and at least 1 person from Fink. But \
only as far as a reasonable effort to have Qt-based software that also runs when \
started with <code style="text-rendering: inherit;color: #4444cc;padding: \
0;white-space: normal;margin: 0;line-height: inherit;">-platform xcb</code>.</p> <p \
style="padding: 0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: \
inherit;">I probably wouldn't mind at all if it were possible to build a full \
X11-based KDE (4 or 5) desktop to run in a rooted X11 window, meaning you can toggle \
between an OS X desktop and a KDE desktop (or between a "PC" and a Unix \
workstation...) with just a keyboard shortcut. But that's just not \
feasible.</p></pre> </blockquote>
</blockquote>
<pre style="white-space: pre-wrap; white-space: -moz-pre-wrap; white-space: \
-pre-wrap; white-space: -o-pre-wrap; word-wrap: break-word;"><p style="padding: \
0;text-rendering: inherit;margin: 0;line-height: inherit;white-space: inherit;">Ah, I \
didn't think that there might be a mac-specific group to add. I'll bear that in mind \
for the future.</p> <p style="padding: 0;text-rendering: inherit;margin: \
0;line-height: inherit;white-space: inherit;">Ideally, X11-specific code should also \
be runtime-wrapped in checks for the QPA backend (also for Wayland on Linux). \
Theoretically, it should be possible to build KDE software with X11 support on a mac \
that would work in either mode. I'm not exactly sure what the issue with building \
KCrash on Mac was, but as Samuel Gaist noted, we're short on people who care about \
X11-on-OS-X and have the time and desire to work on stabilising that support. Given \
that, defaulting to the "usual" case (of not having X11 support on OS X), which is \
better tested, seems reasonable.</p></pre> <br />
<p>- Alex</p>
<br />
<p>On September 15th, 2015, 10:50 p.m. UTC, Samuel Gaist wrote:</p>
<table bgcolor="#fefadf" width="100%" cellspacing="0" cellpadding="12" style="border: \
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<td>
<div>Review request for Extra Cmake Modules.</div>
<div>By Samuel Gaist.</div>
<p style="color: grey;"><i>Updated Sept. 15, 2015, 10:50 p.m.</i></p>
<div style="margin-top: 1.5em;">
<b style="color: #575012; font-size: 10pt;">Repository: </b>
extra-cmake-modules
</div>
<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Description </h1>
<table width="100%" bgcolor="#ffffff" cellspacing="0" cellpadding="10" \
style="border: 1px solid #b8b5a0"> <tr>
<td>
<pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: \
-moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: \
break-word;">Disable X11,XCB etc. detection on OS X</pre> </td>
</tr>
</table>
<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Testing </h1>
<table width="100%" bgcolor="#ffffff" cellspacing="0" cellpadding="10" style="border: \
1px solid #b8b5a0"> <tr>
<td>
<pre style="margin: 0; padding: 0; white-space: pre-wrap; white-space: \
-moz-pre-wrap; white-space: -pre-wrap; white-space: -o-pre-wrap; word-wrap: \
break-word;"><p style="padding: 0;text-rendering: inherit;margin: 0;line-height: \
inherit;white-space: inherit;">KCrash build on OS X 10.8</p></pre> </td>
</tr>
</table>
<h1 style="color: #575012; font-size: 10pt; margin-top: 1.5em;">Diffs</b> </h1>
<ul style="margin-left: 3em; padding-left: 0;">
<li>kde-modules/KDECMakeSettings.cmake <span style="color: \
grey">(0c997931abee8673ccecc66d122108c6f72bf9b1)</span></li>
</ul>
<p><a href="https://git.reviewboard.kde.org/r/125163/diff/" style="margin-left: \
3em;">View Diff</a></p>
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