Hi!

2013/3/23 Greg Alexander <stella@galexander.org>
I checked out the bazaar repository, rev 5924, and built it and
discovered two separate issues that caused Stellarium to crash on startup
on my computer.  I'm new to Stellarium development (and to Bazaar) so I
hope I'm not doing this wrong...

I think this was you on IRC :)
 

First, the new solar system shadows are enabled by default, but if they
are initialized without StelRenderer::areFloatTexturesSupported() then
that triggers an assert failure in
StelRenderer::createTexture(void*,QSize,TextureDataFormat,TextureParams&).
I believe I saw this before other users because I am using unaccelerated
(software rendered) MesaGL.  My proposed remedy is to disable solar system
shadows (regardless of the config parameter) if float textures are
not supported.

ok. I'm apply this patch - it's a logical and nothing broken :)
 

Second, StelQGLGLSLShader.uniformStorage can be unaligned, both because
its start position may be unaligned and because it may contain members
(such as bool) which would introduce misalignment in subsequent members.
I believe I saw this before other users because I am running on ARM,
which gives a fatal SIGBUS for unaligned memory access.  My proposed
remedy is to enforce a minimum alignment in uniformStorage corresponding
to sizeof(void*), which should be harmless on most platforms, a slight
performance improvement on some, and the difference between
crashing-or-not on a few.  Note that I use the GCC

This patch works for the unaccelerated mode (GL1) but it broken the accelerated mode (GL2). 

 
__attribute__((aligned(n))) extension.  I noticed that the similar GCC
extension __attribute__((packed)) was already used in Stellarium, so
 hopefully that is not forbidden...

Well, you should use #ifdef defined(__GNUC__) for GCC extension because Stellarium build via clang too. :)
 
As an aside, I am working on the development branch of Stellarium because
I am attempting to improve the performance on my new laptop that does not
have accelerated GL drivers.  At first glance, the new build from Bazaar
appears to be about 400% slower than the 0.11.4 that I had been working
with, so that is where my focus will be if I have any future
contributions.

You can register at launchpad and create a branch for Stellarium - I think this will be better way for coding and applies patches. 
 
And thanks -- Stellarium is simply the best!!  Even at 1fps, I find I
can't live without it.

Thanks!
 
--
With best regards, Alexander