Re: mxe-octave status

[PhilipNienhuis]

John W. Eaton wrote
> With current Octave and mxe-octave the default-octave target works forme 
> when doing builds for native GNU systems and cross compiling for 
> Windows-64 with either qt4 or qt5.  I'm also building libGL from the 
> Mesa package for consistent software rendering (more about that below). 
> Here are the configurations I'm using:
> 
> Options common to all builds:
> 
>    --with-pkg-dir=/a/common/dir/for/source/downloads
>    --with-ccache
>    --enable-octave=default
>    --enable-binary-packages
>    --enable-devel-tools
>    --disable-system-opengl
> 
> Windows builds (the common options above, plus):
> 
>    --enable-windows-64
> 
> :
> <snip>
> :
> 
> On Windows systems with qt4, I'm able to move aside the mesa version of 
> opengl32.dll and use the Windows OpenGL library (confirming with 
> __opengl_info__).  But with qt5, doing that causes Octave to freeze.  I 
> assume it's a segfault, but I haven't been successful with any attempt 
> at debugging.

FWIW, in latest Octave 4.3.0+ built with qt5 and up-to-date mxe-octave incl.
your mesa patches, __opengl_info__ runs fine & relatively fast with NVidia
graphics hardware en newer Intel hardware (all with OpenGL v. 3.3.0) on my
Windows boxes at home.
At work, with older Intel HW and with virtualized sessions ("VMWare VGA 3D"
graphics adapter), that same Octave build only freezes the first time when
invoking __opengl_info__ or any plot function, after that my Windows
installations issue messages that they detected problems with Octave and
have automatically applied "compatibility settings" to it. To no avail as
the next time graphics functions are invoked Octave just crashes immediately
- indeed a segfault AFAICS.
Do I suppose correctly those crashes are due to the mesa patches? until
recently I never encountered problems using graphics functions in Octave on
that older HW at work.

Maybe it is of some comfort that Matlab on that same older Intel & virtual
HW automatically disables opengl hardware rendering and falls back to
software rendering. I suppose Matlab just checks if OpenGL >= 2.1 (minimum
version), its docs say best performance requires OpenGL 3.3.0.

Could Octave be learned the same trick? that is, disabling hardware OpenGL
if it finds "non-compatible graphics HW" ? Probably be too much trouble if
that would only be required for Windows.

Philip



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