[mythtv] Illegal Instruction - maybe not what you'd think?

[Dave Caplinger]

I just built 0.7; I've successfully built and used versions of MythTV
since 0.4 all on the same hardware, but now when I build 0.7 I get
"Illegal Instruction" when I try to run mythtv. (mythfrontend and
mythepg work fine)

The first thing I thought of was "oh, the settings.pro file must have a
different architecture in it now" since every single time this comes up
Isaac says "modify settings.pro to something appropriate for your
architecture." :-)  However, I compared settings.pro from 0.6 and 0.7
and they are the same.  It still says -march=pentiumpro, and I still
have a Celeron 300A(@450MHz), which is a Pentium-II as far as I know,
that has always worked fine with this setting.

Someplace else on the list I saw mention that this might be somehow
related to MMX vs MMX2 instructions (a Celeron has MMX but not MMX2, for
example... but this is the same as a Pentium Pro).  Does this mean that
someplace in the code it assumes MMX2 support if you have MMX?  If I
knew how to check this myself I would, sorry. If so, is that a myth bug,
a QT qmake bug, not a bug at all, etc.?

Just to be perfectly clear: yesterday I was running 0.6 on this box and
I have changed nothing except to build 0.7.

- Dave

PS - does anyone have a list of what all of those "appropriate" -march=
architecture names are?