Re: can't boot with kern.mmxopt=1

[Richard Nyberg <rnyberg@xxxxxxxx>]

At Tue, 4 May 2004 09:09:49 -0700 (PDT),
Matthew Dillon wrote:
> 
> :Sorry! It still hangs in the same place. I tried to break to DDB but
> :nothing happened. I even had to pull the plug to turn it off!
> :
> :I'll try your first patch this afternoon. However if it hangs and I
> :_can_ break to DDB, I'm still not sure what to look for and how. Could
> :you give some hints?
> :
> :Can you set the dumpdev from the loader? In that case maybe I could
> :generate a core dump for you to look at. If that would be of interest.
> :
> :Anyway, hopefully it works and I don't have to dance with DDB.
> :
> :        -Richard
> 
>     Maybe it's related to the HTT (hyper threading technology).  What happens 
>     if you do a UP build on that machine instead of SMP ?
> 

To eliminate HTT I did this:
Hacked mp_machdep.c to never use logical cpu's.
Disabled hyperthreading in bios.

Using a SMP kernel with vanilla sources + mp_machdep.c hack
and kern.mmxopt=1:
Second CPU enabled: hangs as previously described.
Second CPU disabled: works!

Unfortunately I still can't break to DDB so I can't see what's happening.
At least we're slowly eliminating possible causes :)

Regards,
        -Richard