Mailing List Archive: Illegal Instruction - maybe not what you'd think?

Illegal Instruction - maybe not what you'd think?

Nov 14, 2002, 9:30 PM

Post #1 of 3 (1328 views)

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?

Re: Illegal Instruction - maybe not what you'd think? [ In reply to ]

ijr at po

Nov 14, 2002, 9:38 PM

Post #2 of 3 (1275 views)

Permalink

On Thursday 14 November 2002 11:30 pm, Dave Caplinger wrote:
> 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.

The deinterlacing has _always_ been MMX2. It's a bug in that I don't probe
for it, really. Maybe the upgrade turned it on, and you had it off before?

Isaac

Re: Illegal Instruction - maybe not what you'd think? [ In reply to ]

dent at cox

Nov 15, 2002, 12:08 AM

Post #3 of 3 (1310 views)

Permalink

On Thu, 2002-11-14 at 22:38, Isaac Richards wrote:
> The deinterlacing has _always_ been MMX2. It's a bug in that I don't probe
> for it, really. Maybe the upgrade turned it on, and you had it off before?

I feel like such an idiot. You're right; I didn't catch that when I was
re-editing the /usr/local/share/mythtv/settings.txt file. Thanks for
the tip.

- Dave